rexresearch.com Patents: Synthetic
Cannabidiol
MICROORGANISMS AND METHODS FOR THE FERMENTATION OF CANNABINOIDS
WO2019071000
Disclosed herein are microorganism and methods that can be used for the synthesis of cannabigerolic acid (CBGA) and cannabinoids. The methods disclosed can be used to produce CBGA, ?9-tetrahydrocannabinolic acid (THCA), cannabidiolic acid (CBDA), cannabichromenic acid (CBCA), ?9 -tetrahydrocannabinol (THC), cannabidiol (CBD), cannabichromene (CBC). Enzymes useful for the synthesis of CBGA and cannabinoids, include but are not limited to acyl activating enzyme (AAE1), polyketide synthase (PKS), olivetolic acid cyclase (OAC), prenyltransferase (PT), THCA synthase (THCAS), CBDA synthase (CBDAS), CBCA synthase (CBCAS), HMG-Co reductase (HMG1), and/or farnesyl pyrophosphate synthetase (ERG20). The microorganisms can also have one or more genes disrupted, such as gene that that controls beta oxidation of long chain fatty acids.
METHOD FOR PURIFYING CANNABINOID COMPOUNDS
CA3023760
The present invention relates to methods for purifying one or two cannabinoid compounds using simulated moving bed chromatography, wherein the cannabinoid compound(s) is/are obtained in the extract and/or the raffinate with the total amount of isomeric impurities being below detection level. In particular, the present invention relates to methods for the purification of cannabidiol, trans-(-)-delta-9-tetrahydrocannabinol, cannabidivarin, trans-(-)-delta-9-tetrahydrocannabivarin and cannabigerol which have been obtained by enantiopure synthesis.
[0002] The present invention relates to methods for purifying one or two cannabinoid compounds using simulated moving bed chromatography, wherein the canna- binoid compound(s) is/are obtained in the extract and/or the raffinate with the total amount of isomeric impurities being below detection level. In particular, the present invention relates to methods for the purification of cannabidiol, trans-(-)- delta-9-tetrahydrocannabinol, cannabidivarin, trans-(-)- delta-9- tetrahydrocannabivarin and cannabigerol which have been obtained by enantiopure synthesis. Furthermore, the present invention also relates to an extract and/or raffinate which is/are obtained or obtainable by the method accord- ing to the invention. Since the discovery of the endogenous cannabinoid system with its functional significance in terms of the regulation and modulation of the immune as well as the nervous system, there is an ongoing need for natural and artificial canna- binoids for their selective, pharmaceutical control. In particular, because of their different medical functions, there is a need for targeted, separate stimulation of ao the cannabinoid receptors CB1, which are mainly found in neurons, in highest density in basal ganglia, in the hippocampus and the cerebellum, and of the cannabinoid receptors CB2, which are mainly found on cells of the immune sys- tem and on cells that are involved in bone formation and bone loss. CA 03023760 2018-11-09 WO 2017/194173 PCT/EP2016/060905 - 2 - The cannabinoid receptors CB1 and CB2 are presumed to be the accepted sites of action of molecules with a cannabinoid structure. Even though further recep- tors are discussed as potential CB3 receptors, it is assumed that the main effects are mediated via CB1 and CB2. Delta-9-tetrahydrocannabinol (delta-9-THC), endogenous cannabinoids and a multitude of synthetic cannabinoids connect to said receptors and exert through them an effect on the cells (Pertwee, R. G. et al. Pharmacol. Rev. 2010, 62, 588-631). CB1 and CB2 are members of the superfamily of the G protein coupled receptors (GPCRs). More precisely, the receptors inhibit the adenylate cyclase via the .. heteromeric G protein and activate the mitogenically activated protein kinase (Howlett, A. C. et al. Pharmacol. Rev. 2002, 54, 161-202; Howlett, A. C. Handb. Exp. Pharmacol. 2005, 168, 53-79). In terms of the CB1 receptor it is further described that it can modulate potassium flows via ion channels of the A-type and calcium flows via N as well as P/Q-type channels. Furthermore, CB1 receptors are able to transfer signals to the expressing cells via Gs proteins (Glass, M., Felder, C. C. J. Neurosci. 1997; 17, 5327-5333; Maneuf, Y. P., Brotchie, J. M. J. Pharmacol. 1997; 120, 1397-1398; Calandra, B. et al. Eur. J. Pharmacol. 1999; 374, 445-455; Jarrahian, A. et al. J. Pharmacol. Exp. Ther. 2004, 308, 880- 886). The ability of CB1 and CB2 to transfer signals via Gy0 and further downstream via 2o .. inhibition of the adenylate cyclase, is used in the so-called [35S]GTP gammaS binding assay and the cAMP assay (Howlett, A. C. et al. Pharmacol. Rev. 2002, 54, 161-202; Pertwee, R. G. Handb. Exp. Pharmacol. 2005a, 168, 1-51) to ana- lyze the binding and signal transduction of cannabinoids. CB1 receptors have at their disposal an orthosteric as well as one or multiple allosteric binding site(s), which are considered as potential sites of action for ligands (Price, M. R. et al. Mol. Pharmacol. 2005a, 68, 1484-1495; Adam, L. et al. 17th Annual Symposium of the Cannabinoids, 2007, S. 86; Horswill, J. G. et al. J. Pharmacol. 2007, 152, 805-814; Navarro, H. A. et al. J. Pharmacol. 2009, 156, 1178-1184). CB1 receptors are mainly found on the terminal ends of central and peripheral neurons, where they usually impart an inhibition of excitatory and inhibitory neurotransmitters (Howlett, A. C. et al. Pharmacol. Rev. 2002, 54, 161- CA 03023760 2018-11-09 WO 2017/194173 PCT/EP2016/060905 - 3 - 202; Pertwee, R. G., Ross, R. A. Prostaglandins Leukot Essent Fatty Acids, 2002, 66, 101-121; Szabo, B., Schlicker, E. Handb. Exp. Pharmacol. 2005, 168, 327-365). The distribution of these receptors in the central nervous system is in such a way that their activation can influence different cognitive processes (e.g. alertness and memory, different motor functions und pain perception). CB2 receptors are mainly localized, as mentioned before, in immune cells. Once they get activated, they modulate cell migration and the release of cytokines inside and outside the brain (Howlett, A. C. et al. Pharmacol. Rev. 2002, 54, 161- 202; Cabral, G. A., Staab, A. Handb. Exp. Pharmacol. 2005, 168, 385-423; Pertwee, R. G. Handb. Exp. Pharmacol. 2005a, 168, 1-51). There is also some evidence that firstly CBI receptors are expressed by non- neuronal cells (including immune cells) (Howlett, A. C. et al. Pharmacol. Rev. 2002, 54, 161-202) and that secondly CB2 receptors are expressed by some cells inside and outside the brain (Skaper, S. D. et al. Proc. Natl. Acad. Sci. USA 1996, 93, 3984-3989; Ross, R. A. et al. Neuropharmacology 2001a, 40, 221-232; Van Sickle, M. D. et al. Science 2005, 310, 329-332; Wotherspoon, G. et al. Neuroscience 2005. 135, 235-245; Beltramo, M. et al. Eur. J. Neurosci. 2006, 23, 1530-1538; Gong, J. P. et al. Brain Res. 2006, 1071, 10-23; Baek, J. H. et al. Acta Otolaryngol 2008, 128, 961-967). Known compounds, which have been proven to have an affinity for the aforemen- tioned receptors CBI and CB2, are amongst others cannabidiol (CBD) and cer- tain chemical derivatives thereof. In particular the active compound delta-9-tetrahydrocannabinol (delta-9-THC) from the cannabis plant has become a focus of attention in the last couple of years. Reduced to only its psycho-active effects in the past, recent studies show a more diverse range of effects. Applications in cancer and HIV therapy as well as in the treatment of multiple sclerosis are found. The (-)-enantiomer has been found to be the more active one (Jones, G. et al., Biochem. Pharmacol., 1974, 23: 439; Roth, S. H., Can. J. Physiol. Pharmacol., 1978, 56: 968; Martin, B. R. et al., Life Sciences, 1981, 29: 565; Reichman, M. et al. Mol. Pharmacol., 1988, 34: CA 03023760 2018-11-09 WO 2017/194173 PCT/EP2016/060905 - 4 - 823; Reichman, M. et al., Mol. Pharmacol., 1991, 40: 547). Therefore an enantiopure product is desirable. Since the isolation of pure trans-(-)-delta- 9-THC from cannabis sativa or indica is a very time consuming and expensive process (WO 2002/045115 Al), trans-(-)-delta-9-THC is more and more synthetically produced under the name dronabinol. This is either done in a partially synthetic way by conversion of the precursor isolated from the cannabis plant, trans-(-)- cannabidiol, to dronabinol (WO 2002/045115 Al) or fully synthetic as described in EP 2842933 Bl. Different cannabinoid compounds and methods for their manufacture are known io from the prior art. Korte et al. (Tetrahedron Letters, 1968, 3, 145-7) describe cannabidivarin for the first time and propose a synthesis analogous to the one by Petrzilka et al. (Hel- vetica Chimica Acta, 1967, 50, 719-723). However, only low yields can be achieved this way. Also Crombie et al. (Phytochemistry 1975, 4, 11975) describe the synthesis of cannabidivarin in small scale as condensation of divarin with para- menthadienol. The synthesis in dried CH2C12, saturated with PTSA, however, is not very selec- tive and the resulting products are obtained at uneconomical proportions. Tetrahydrocannabivarin (here denoted delta-1-tetrahydrocannabivarol) is gener- ated the same way at higher temperatures and at an uneconomical concentration in a multiple compound mixture. WO 2006/136273 describes a method for the manufacture of dronabinol ((denot- ed (6a R- trans)-6a,7,8,10a-tetrahydro-6 ,6,9-trimethy1-3-penty1-6 H- dibenzo[b,d]pyran-1-ol, g-tetrahydrocannabinol (A9-THC) in the WO document), nowadays according to IUPAC also denoted (6aR,10aR)-6,6,9-trimethy1-3-penty1- 6a,7,8,10a-tetrahydro-6H-benzo[c]chromen-l-ol or delta-9-tetrahydrocannabinol, delta-9-THC or A-9-THC) from cannabidiol (CBD) via cyclization of cannabidiol (CBD) (2-[1R-3- methyl-6-(1-methyletheny1)-2-cyclohexene-1-y1]-5-penty1-1,3- benzenediol) to yield delta-9-THC. The described method is characterized in that .. cannabidiol (CBD) is provided in an organic solvent and is heated and cyclized to delta-9-THC in the presence of a molecular sieve. It is stated in WO 2006/136273 CA 03023760 2018-11-09 WO 2017/194173 PCT/EP2016/060905 - 5 - that the used molecular sieve exhibits, besides the drying properties that have been described so far, strong catalytic properties, which are in the focus of the described conversion. Cyclizations that can only be performed in the presence of a Lewis acid catalyst are usually significantly slower and deliver worse yields of delta-9-THC than cyclizations that are performed in the presence of a molecular sieve. Further types of syntheses are described in the literature, e.g. by Crombie et al. Chem. Research 1977, 114, 1301-1345. More recent synthesis methods are disclosed inter alia in EP 2314580. The method for the manufacture of canna- binoids described therein, is supposed to be applicable to all stereoisomers and homologs of cannabinoids and consists of two and three chemical synthesis steps, respectively. In a first step, alkyl resorcylic acid esters (6-alkyl- 2,4- dihydroxybenzoic acid ester) are thereby condensed with unsaturated hydrocar- bons, alcohols, ketones (and their derivatives such as enol esters, enol ethers and ketals, respectively) to the corresponding 6-alkyl-2,4-dihydroxybenzoic acid esters that are substituted at the 3-position. In a second step, the ester function- containing intermediates that were produced in the first step are subjected to a decarboxylating saponification, giving rise to the corresponding ester-free canna- binoids. If necessary, an acid catalyzed rearrangement is carried out in a third step. This isomerization may be e.g. the ring closure of the pyran ring of CBD to give dronabinol, but also the rearrangement of a double bond like e.g. the reor- ganization of delta-9 to delta-8-THC or an acid catalyzed epimerization like the rearrangement of cis-9-ketocannabinoids to the corresponding trans-compounds. US 5,342,971 describes a method for the manufacture of dronabinol and of the related dibenzo[b,d]pyrans. These are produced, according to the abstract, through heating of a dihydroxybenzoic acid derivative in the presence of a Lewis acid catalyst and an inert non-polar solvent, in which indeed the dihydroxybenzoic acid is soluble, but the Lewis acid catalyst is insoluble or only very slightly soluble. .. EP 2842933 B1 discloses a method for synthesizing delta-9-THC starting from menthadienol. In a first step, menthadienol is reacted with an olivetolic acid ester to a cannabidiolic acid ester. This ester is then subjected to a transesterification CA 03023760 2018-11-09 WO 2017/194173 PCT/EP2016/060905 |EPO DP num="6"|
[0003] and the product is saponified and decarboxylated to cannabidiol. In the last step, cannabidiol is cyclised to trans-(-)-delta-9-THC in enantiopure form. oH a) EiF3*()Etz TBME, RT. 3t1 OH > b) chromatographic purification = /HO 60% (I) (II) (III) menthadienol cannabidiol trans-(-)-delta-9-tetrahydrocannabinol Details of the synthesis of delta-9-THC according to EP 2842933 B1 can be found in example 1. Analogously, a synthesis of cannabidivarin (CBDV) and tetrahydrocannabivarin (THCV) starting with reacting menthadienol with a divarinic acid ester, followed io by transesterification, saponification and decarboxylation to cannabidivarin and subsequent cyclisation to tetrahydrocannabivarin is described in European patent application EP 15156750Ø The product is also obtained in enantiopure form as trans-(-)-delta-9-THCV. An example of the synthesis steps for cannabidivarin (CBDV) and tetrahydrocannabivarin (THCV) as described in European patent application EP 15156750.0 is shown schematically below. Reaction conditions can be in- ferred from example 2. CA 03023760 2018-11-09 WO 2017/194173 PCT/EP2016/060905 |EPO DP num="7"|
[0004] 1. Coupling step: OH OH 0 itV 111 + OH 0 1 010 HO =>i HO (I) (IV) (V) menthadienol divarinic acid methylester .. cannabidivarinic acid methylester 2. Transesterification step: OH 0 OH 0 % HO % HO (V) (VI) cannabidivarinic acid methylester 2-hydroxyethylcannabidivarinolate 3. SaDonification/decarboxylation step =H 0 OH 140 -a. HO ./ .1 HO ===>1 (VI) (VII) 2-hydroxyethylcannabidivarinolate cannabidivarin CA 03023760 2018-11-09 WO 2017/194173 PCT/EP2016/060905 |EPO DP num="8"|
[0005] 4. Cyclization step 401 'H 1110 CH 110 7HO -J**ttl 1101 (VII) cannabidivarin trans-(-)-delta-9-tetrahydrocannabivarin The raw product generated by the above mentioned synthesis according to EP 2842933 B1 has a delta-9-THC content of 65 - 75 %, as well as 20 - 30 % of the isomer delta-8-tetrahydrocannabinol as main impurity. The purification of trans-(-)-delta-9-THC proves difficult because it can not be obtained in crystalline form. Pure delta-9-THC is a slightly yellow, air- sensitive resin. Therefore, a crystallization as with the related cannabinoids, cannabidiol or cannabidivarin is not possible when an enantiopure product is desired. Distillation is also not feasible due to the high boiling point (about 200 C at 0.02 mbar) and its thermal instability. A particular complication is the presence of structurally very similar compounds with almost identical chemical and physical properties (polari- .. ty, boiling point etc.), which may impede purification, such as the two isomers delta-8-tetrahydrocannabinol and delta-9(11)-tetrahydrocannabinol. H OH A8 - Tetrahydrocannabinol A9(11)- Tetrahydrocannabinol The same problems arise for the raw product obtained by the synthesis of THCV as described above, where the corresponding isomers are formed. CA 03023760 2018-11-09 WO 2017/194173 PCT/EP2016/060905 |EPO DP num="9"|
[0006] For these reasons, expensive and time consuming chromatographic methods are employed. WO 2002/062782 Al discloses a method for the production of dronabinol starting with the isolation of cannabidiol from fibrous hemp, which is then chemically cyclised. According to the examples of WO 2002/062782, the resulting reaction mixture comprises up to 86 % of dronabinol, which is then isolated chromato- graphically on a silica gel column. The solvent is removed and the product is purified by high vacuum distillation or crystallization. However, as indicated above, distillation of dronabinol is highly inefficient because of its thermal instabil- ity and crystallization is only possible with an enantiomeric mixture. According to WO 2009/133376 Al, delta-9-THC and delta-9-THC carboxylic acid are extracted from plant material and then the delta-9-THC carboxylic acid is converted to delta-9-THC in the same solvent. For further purification, the product is run over a charcoal column, the fractions containing delta-9-THC are com- bined, concentrated and then purified by reverse phase chromatography. Again, the combined fractions containing the product are concentrated, extracted with MTBE and filtered. Ethanol is added to the filtrate and the solution is concentrat- ed to produce an oil, from which the solvent is evaporated. US 2015/0126596 Al relates to methods for producing trans-(-)-delta-9-THC and trans-(+)-delta-9-THC in several different ways. In one case, the preparation is started with an enantiomeric mixture, where the two enantiomers are purified together by preparative HPLC and then crystallized as a mixture after which, in a resolving step, the (+/-)-enantiomers are separated by chiral chromatography. Another way starts also with an enantiomeric mixture, which is reacted to a nitro- benzene sulfonate, crystallized and reacted back to a clean enantiomeric mixture, which is then again separated by chiral chromatography. A further way is de- scribed, in which the two separate enantiomers are synthesized, mixed for crys- tallization and subsequently separated again by chiral chromatography. To purify trans-(-)-delta-9-THC by crystallization with the (+)-enantiomer and subsequent chiral separation, however, appears to be a very complicated purification method, which is bound to result in a considerable loss of material and hard to scale up in an efficient way. CA 03023760 2018-11-09 WO 2017/194173 PCT/EP2016/060905 |EPO DP num="10"|
[0007] Preparative HPLC is only successful on a very small scale when large losses of yield are to be avoided. Only small amounts of raw product (25 mg) can be sepa- rated into Dronabinol and the main impurity, delta-8-THC, as demonstrated in Figures la) and 1b). Fig. la) shows the preparative HPLC purification of 25 mg raw product obtained in the synthesis according to EP 2842933 B1 , wherein the two peaks are dronabinol as main product (larger peak) and delta-8-THC as main impurity (smaller peak). Fig. 1 b) shows the preparative HPLC purification of 200 mg raw product comprising dronabinol as main product and delta-8-THC as main impurity, demonstrating that these compounds can not be resolved in this quanti- ty. A further chromatographic purification method is super critical fluid chromatog- raphy (SFC), in which liquid CO2 is used as eluant. The purification of (-)- delta-9- trans-THC by SFC is described in WO 2005/061480 Al. This process, however, requires a complex constructional setup and is very expensive. Moreover, the CO2 evaporates and is lost during processing. Further methods are derivatisations of dronabinol or precursors thereof to com- pounds which may be crystallized. In order to perform a crystallization, the raw product is converted into a crystallizable derivate, which is then purified by crys- tallization and finally converted back to dronabinol in a chemical conversion step. The most relevant methods comprise the derivatisation of delta-9-THC to suitable crystallizable salts, subsequent crystallization and thermal decarboxylation to dronabinol as described in WO 2013/045115 Al. A further option is the derivatisation of raw dronabinol to a 1-naphtoyl ester, subsequent crystallization and finally saponification to pure dronabinol (see WO 2006/007734 Al). In summary, the methods to purify cannabinoid compounds available in the prior art are fairly complicated, time-consuming and expensive. Moreover, certain impurities derived e.g. from synthetic preparation steps, which may be structurally very similar such as isomers of the desired product, can not be removed to a satisfactory degree. This is especially true when the process is to be carried out on an economically relevant scale. CA 03023760 2018-11-09 WO 2017/194173 PCT/EP2016/060905 |EPO DP num="11"|
[0008] As a result, there is still a need to provide a method for the purification of canna- binoid compounds, which is suitable to achieve a maximum degree of purity while at the same time allowing purification on a large scale in an economically appro- priate, i.e. a time and cost efficient way. Simulated moving bed chromatography (SMB chromatography) is a continuous process based on the true moving bed principle, in which the solid phase moves in the opposite direction to the liquid phase and is therefore not stationary. Due to this opposing movement two pure compounds can be isolated or a pure com- pound can be isolated from a complex mixture. io The moving solid phase on which this concept relies, however, is technically not feasible and therefore simulated. This is implemented by arranging several pre- parative columns connected in series and periodically changing the valve setting so that a movement of the solid phase in the opposite direction of the flow of the liquid phase is simulated. The system is continuously fed with a feed mixture comprising the compounds to be separated and an eluant while a raffinate and an extract are continuously withdrawn from the system. The system is therefore divided into four different separation zones, in each of which the same number of columns are distributed. The process shown in Figure 2 comprises 8 columns in total, but alternatively, only four may be used. By periodically switching the feed, eluant, extract and raffinate ports in the same direction, each column passes through each zone once per cycle. The feed mixture is fed into the system between zones II and III, in which the actual separation occurs. Zones I and IV are regeneration zones. The parameters, which are important for the SMB principle, are the periodical change of the position of the ports as well as the different flow rates in the four zones. These four flow rates are regulated by four pumps. The extract pump in zone II and the raffinate pump in zone IV are inside the column circle, the eluant and the feed pump are located outside of the column circle. A fine regulation is achieved by two needle valves, which regulate the ratio between the circle flow and the outlet flow. CA 03023760 2018-11-09 WO 2017/194173 PCT/EP2016/060905 |EPO DP num="12"|
[0009] While the prior art does not provide a process for the purification of cannabinoid compounds, which is suitable to achieve a purity level comparable to the process according to the present invention as described below, in particular when per- formed at a preparative scale, it has now been found out, that the purification of cannabinoid compounds using a simulated moving bed chromatographic system, preferably in combination with one or more additional extraction step(s), provides one or two desired cannabinoid products with an unexpectedly high degree of purity while still allowing the process to be implemented on an economically relevant scale. io This finding was unexpected as conventional silica gel chromatography of larger amounts of dronabinol fails to provide a viable option to separate the product from its isomers, while it is on the other hand not feasible to scale up reversed phase HPLC chromatography to preparative significant amounts. The method according to the invention, however, surprisingly compensates both theses prob- lems and provides a way to obtain pure product on a large scale. It was therefore an objective of the present invention to provide a purification method which overcomes the above mentioned problems. In particular, it was an objective of the present invention to provide a purification process for one or two cannabinoid compound(s) from a reaction mixture derived 2o from a synthetic preparation process, especially a process as described in EP 2842933 B1 . It was also an object of the present invention to obtain the desired cannabinoid compound(s) in a degree of purity that any of its/their isomers are below a detec- tion level and furthermore in enantiopure form. The objectives given above are met by a method for purifying one or two can- nabinoid compounds comprising the steps: i) providing a mixture comprising at least one cannabinoid compound obtained by enantiopure synthesis and one or more of its isomers and optionally one or more further organic compounds, and CA 03023760 2018-11-09 WO 2017/194173 PCT/EP2016/060905 |EPO DP num="13"|
[0010] ii) simultaneously, a) continuously feeding the mixture of step i) through a feed port into a simulated moving bed chromatographic apparatus com- prising at least four columns connected in series and containing a stationary phase, and b) continuously feeding eluant into the apparatus through an eluant port, and c) continuously withdrawing the extract through an extract port, and d) continuously withdrawing the raffinate through a raffinate port, wherein the extract and/or the raffinate respectively comprise(s) one purified cannabinoid compound and wherein the extract and/or the raffinate comprising one purified cannabinoid compound comprise(s) less than 100 ppm, preferably less than 70 ppm, particularly preferably less than 50 ppm in total of any iso- mer(s) of the purified cannabinoid compound present in step i). As described above, SMB chromatography allows separation and purification of one or simultaneously two desired product compounds, the stronger adsorbing compound is obtained as the extract and the weaker adsorbing compound is obtained as the raffinate. Advantageously, a mixture comprising at least one cannabinoid compound together with at least one of its isomers, such as a reac- tion mixture from a synthesis step, may be subjected to the method according to the invention to provide highly pure products in large yields. The at least one cannabinoid compound and its isomer(s) present in the mixture provided in step i) are likely very similar in chemical structure and therefore also in their physical properties. Consequently, they are particularly hard to separate. Using the meth- od according to the present invention, however, the cannabinoid compound(s) can efficiently be separated from their isomers. CA 03023760 2018-11-09 WO 2017/194173 PCT/EP2016/060905 |EPO DP num="14"|
[0011] The one or more further organic compound(s) present in the mixture provided in step i) may be any compound(s) selected from synthetic starting materials or side products of the synthesis, which are not cannabinoid compounds. As the steps a) to d) are carried out simultaneously and continuously, the process is very time efficient and the required amount of eluant is significantly reduced compared to conventional chromatography. Additionally, it is advantageous that the solid phase can be used for separation during the entire process. This in- creases the efficiency of the separation and simultaneously reduces the required amount of eluant. Once the adsorption equilibrium is reached, the composition of io .. the raffinate and extract do not change anymore as long as the respective pa- rameters are not changed. The loss of valuable materials is reduced to <5%. As a simulated moving bed chromatographic apparatus, any system suitable to perform simulated moving bed chromatography may be used. The stationary or solid phase may be any material, which the skilled person can easily choose according to the nature of the mixture and the compounds to be separated. To determine the respective flow rates at the different pumps, several methods and models are known in the prior art which may be implemented in order to achieve an optimal separation of the desired compound(s). The desired compound(s) is/are obtained in the extract and/or the raffinate in a degree of purity with respect to any isomer of the desired cannabinoid com- pound(s), which is preferably below detection limit, in particular the total amount of any isomer of the cannabinoid compound(s) which was/were present in step i) is less than 100 ppm, preferably less than 70 ppm and particularly preferably less than 50 ppm. The degree of purity may be determined chromatographically using an HPLC apparatus (e.g. Knauer HPLC smartline series) and the appropriate USP reference standards for dronabinol and its isomers. A Restek - Raptor (ARC - 18, 2.7 mm, 150 x 4.6 mm) HPLC column may be used together with the re- spective USP eluent (45 % methanol, 25 % water, 20 % tetrahydrofuran, 10 % acetonitrile) with an eluent flow of 0.8 mL / min. .. According to a further aspect the method as described above additionally com- prises the step CA 03023760 2018-11-09 WO 2017/194173 PCT/EP2016/060905 |EPO DP num="15"|
[0012] iii) subjecting the extract and/or the raffinate comprising one purified cannabinoid compound to one, two or more further extraction step(s), preferably using an oil as the extracting agent, wherein the extract and/or the raffinate respectively obtained in step iii) com- prise(s) one purified cannabinoid compound and less than 100 ppm, preferably less than 70 ppm, particularly preferably less than 50 ppm in total of any further organic compound(s) present in step i). By subjecting the desired cannabinoid compound(s) which is/are contained in the extract and/or the raffinate to one or more further extraction step(s), impurities io other than the isomers present in step i) can be removed. In particular, organic compounds, which may be present from the synthetic step such as starting mate- rials or side products of the synthesis can be removed to a degree such that they are present in an total amount of less than 100 ppm, preferably less than 70 ppm, particularly preferably less than 50 ppm. The extraction agent may be any substance selected from the group consisting of cyclohexane, heptane and other oxygen free hydrocarbons. Suitable oils to be used as extracting agents are selected from the group consist- ing of plant oils with medium chain triglycerides, preferably containing the fatty acids capric acid and caprylic acid. Advantageously, when using an oil as extract- ing agent, the resulting product comprising the desired cannabinoid compound ¨ besides being highly pure ¨ is particularly stable when kept under argon and in the dark. In particular, the medium chain triglycerides mentioned above provide an antioxidant effect and therefore enhance the stability of the product. In the method according to the invention, the cannabinoid compound(s) to be purified may be selected from the group consisting of cannabidiol, trans-(-)- delta- 9-tetrahydrocannabinol, cannabidivarin, trans-(-)-delta-9- tetrahydrocannabivarin and cannabigerol. Any of these compounds may be obtained by chemical synthesis as described in the prior art, which results in reaction mixtures comprising one or more canna- binoid compounds such as the desired product and its synthetic precursors, as
[0013] well as at least one isomer of the product compound(s) and further organic com- pounds such as starting materials or side products of the synthesis, which are not cannabinoid compounds. These mixtures can be purified to a high degree and with good yields on a large scale by the method according to the present inven- tion. In a particularly preferred embodiment, the method according to the invention is used to purify the reaction product(s) of the synthesis steps described in EP 2842933 B1 . The reaction product(s) to be purified are preferably trans-(-)- delta- 9-THC (III) or cannabidiol (II). io According to one aspect, in the method according to the present invention step i) includes the following step: conversion of menthadienol with an olivetolic acid ester to a cannabidiolic ac- id ester of formula (IX) OHO 0 'IFIO (IX) wherein Y is an organic residue, preferably in a continuous process. According to a further aspect, step i) comprises the conversion of a cannabidiolic acid ester of formula (IX), wherein Y is an organic residue with an alcohol of the formula HO-X, wherein
[0014] X is an aliphatic residue with one, two, three or more than three hydroxyl groups, wherein the total number of C-atoms in the aliphatic residue X is not greater than 15, and wherein the aliphatic residue is - saturated or unsaturated and - branched or unbranched, wherein Y is different from X and selected such that the alcohol of formula HO- Y, which is generated during the conversion, boils at a lower temperature at 1013 hPa than the used alcohol of formula HO-X. According to yet another aspect of the method according to the invention, the compound generated by the conversion of the cannabidiolic acid ester of formula (IX) with the alcohol of formula HO-X is treated in such a way that it is decarboxylated and saponified to generate cannabidiol (II). In a further aspect of the method according to the invention, the cannabidiol, which is present after the decarboxylating saponification, is cyclised to trans-(-)- delta-9-tetrahydrocannabinol (III), preferably in the absence of halogenated sol- vents. In the synthesis of delta-9-tetrahydrocannabinol according to EP 2842933 B1, an 2o impurity which is very hard to remove is olivetol, which is generated during the synthesis. Surprisingly, when the method according to the present invention is used to purify the product delta-9-THC in combination with the one or more further extraction step(s), any residual olivetol can be removed to such a degree that it is no more detectable by conventional HPLC analysis as demonstrated in example 3.
[0015] Therefore the present invention particularly relates to a method as described above, wherein the one or one of the further organic compound(s) present in step i) is olivetol. Furthermore, as already mentioned in the introduction, the raw product generated by the synthesis according to EP 2842933 B1 has a delta-9-THC content of 65 ¨ 75 %, as well as 20 ¨ 30 A of the isomer delta-8-tetrahydrocannabinol as main impurity. Furthermore, delta-9(11)-tetrahydrocannabinol may be present. Due to the structural similarity of the isomers, the desired delta-9-THC is very hard to purify from this reaction mixture. io Using the method according to the present invention, however, a purity may be obtained such that these isomers can no more be detected in the product as demonstrated in example 3. Therefore in a particularly preferred embodiment, in the method according to the invention, the mixture provided in step i) comprises trans-(-)-delta-9- tetrahydrocannabinol together with delta-8-tetrahydrocannabinol and/or delta- 9(11 )-tetrahydrocannabinol. According to a further preferred embodiment, the method according to the inven- tion is used to purify the reaction product(s) of the synthesis steps described in European patent application EP 15156750Ø The reaction product(s) to be pun- 2o fied are preferably cannabidivarin (VII) or trans-(-)-delta-9- tetrahydrocannabivarin (VIII). According to one aspect in the method according to the present invention, step i) comprises the conversion of menthadienol of formula (I) with a divarinic acid ester of formula (IV), to an ester of formula (V),
[0016] OH OH 0 OH 0 001 + HO HO 14111 (I) (IV) (V) According to a further aspect, in the method according to the invention, step i) comprises the transesterification of the ester of formula (V) with an alcohol of the formula HO-X, wherein X is an aliphatic residue with no, one, two, three or more than three hy- droxyl groups, wherein the total number of C-atoms in the aliphatic resi- due X is not greater than 15, and io wherein the aliphatic residue is - saturated or unsaturated and - branched or unbranched, - acyclic or cyclic, with the proviso that the alcohol of formula HO-X is selected from the group consisting of cyclohexanol and hexanol in case X is an aliphatic residue with no hydroxyl group. According to yet a further aspect, in the method according to the invention, the compound generated by the conversion of ester of formula (V) with the alcohol of
[0017] formula HO-X is treated in such a way that it is decarboxylated and saponified to generate cannabidivarin (VII). In a further aspect of the method according to the invention, the cannabidivarin, which is present after the decarboxylating saponification, is cyclised to trans-(-)- delta-9-tetrahydrocannabivarin (VIII), preferably in the absence of halogenated solvents. The reaction products of the synthesis steps as described in European patent application EP 15156750.0, may be purified by the method according to the invention. The advantages described above in the context of the purification of io the synthesis product(s) according to EP 2842933 apply accordingly. Finally, the present invention also relates to an extract or raffinate obtained or obtainable in step c) or d) of a method as described above, or an extract or raffi- nate obtained or obtainable in step iii) of a method as described in the context of the corresponding embodiment above. An extract or raffinate obtained or obtainable in step c) or d) of a method as described above, or an extract or raffinate obtained or obtainable in step iii) of a method as described in the context of the corresponding embodiment above, comprises the desired cannabinoid compound in a degree of purity, in particular with respect to its isomers, which could not be achieved by any of the conven- tional processes available in the prior art. The following examples describe particular embodiments of the present inven- tion, without meaning to limit the scope of protection. Example 1: Synthesis of delta-9-THC: Step 1: Coupling step (in the continuous process); Synthesis of cannabidiolic acid methyl ester (I)
[0018] a)13F3=0E12, H chi ro b enzene, PT b) NaHCO3, S --- PT, 20 min OH a o 40 - 70% Iv HO 'girl' a H menthadienol olivetolic acid cannabidiolic acid methyl ester methyl ester 300 g (2.0 mol) menthadienol and 476 g (2.0 mol) olivetolic acid ester are dis- solved at ca. 22 C in 1,370 g of chlorobenzene (2,000 mL solution A), likewise 94 g (0.66 mol) boron trifluoride*etherate are dissolved in 640 g of chlorobenzene at ca. 22 C (666 mL solution B)., Solution A at a flow rate of 72 mU min and solu- tion B at a flow rate of 24 mL/ min are pumped into a stirred reaction chamber via two separate dosing pumps, from the reaction chamber the reaction composition runs via a PTFE hose into a stirred solution of 1,000 g of sodium bicarbonate. The total reaction time is ca. 20 min. After termination of the metering the hydro- lyzed reaction solution is stirred for a further 30 min. Then the hydrolyzed reaction solution is transferred into a 5L jacket reaction vessel, the aqueous phase is separated and the solvent chlorobenzene is re- moved in vacuo. Ca. 2,000 g of toluene are added to the remaining 730 g of raw material and the unreacted olivetolic acid ester is extracted through the addition of 1,200 g 1% aqueous sodium hydroxide solution (four times). After acidifying with semi conc. sulfuric acid and re-extraction of this aqueous phase, ca. 30% (140 g) of non converted olivetolic acid ester are recovered. There are ca. 520 g of cannabidiolic acid methyl ester in the toluene phase, which corresponds to a theoretical yield of ca. 70%. This first intermediate serves as starting material for the following transesterification. Step 2: Transesterification, synthesis of 2-hydroxyethyl cannabidiolate:
[0019] /00 C*-1 = KOH, ethylene ghicol OH 0.5 bar,120 0, 2h z /HO --7H0 2-hydra xyethyl cannabidiolate The toluene is removed in vacuo and to the remaining first intermediate 600 g of ethylene glycol are added under stirring followed by a solution of 85 g of potassi- um hydroxide in 300 g ethylene glycol. A vacuum of ca. 0.5 bar is applied and it is heated to 120 C for 2 h, whereby ca. 40 g of methanol distill off. The resulting product composition mainly comprises 2-hydroxyethyl cannabidiolate. Step 3: Saponification/ decarboxylation, synthesis of cannabidiol (X): OH OH 0.5 bar, 150*C, 211 0 60% cannabldol Subsequently, the temperature is increased to 150 C and it is stirred at this io temperature for 2 h. The product composition resulting from the transesterification comprising mainly 2-hydroxyethyl cannabidiolate is cooled down to ca. 40 C and 500 g of water as well as 500 g of n-heptane are added and ca. 150 g of semi conc. sulfuric acid are added for neutralization. After phase separation, the solvent is removed using a rotary evaporator and the remainder is distilled over a thin-film evaporator using a vacuum of ca. 0.5 mbar and a jacket temperature of 230 C. 310 g of cannabidiol are obtained in the form of a viscous, yellowish oil with a purity of 85%, which corresponds to a theoretical yield of 60% in relation to the used cannabidiolic acid ester.
[0020] This viscous, yellowish oil is then recrystallized in ca. 200 g of n-heptane at ca. -5 C, after which 210 g of white crystallizate with a purity of 99% cannabidiol are obtained. Step 4: Cyclization. synthesis of delta-9-THC: SI a) BF3*OEtz, TBME, RI, 3h OH b) chromatographic Purification /HO a 60% cannabidiol d eita-9-THC 50 g of pure cannabidiol are dissolved in 250 g methyl-tert-butylether and 40 g of boron trifluoride*acetic acid complex are added under stirring within 10 min at ca. 22 C. It is stirred for 3 h at said temperature and then 200 g of ice water are added, the organic phase is washed with sodium bicarbonate solution and the io solvent is removed using a rotary evaporator. The remaining raw material of ca. 50 g contains 74% trans-(-)-delta-9-tetrahydrocannabinol (delta-9-THC), 25% of side products as well as < 1% cannabidiol. Example 2: Synthesis of cannabidivarin and tetrahydrocannabivarin: Step 1: Coupling step OH OH 0 + (3* = H = HO 101 HO (I) (IV) (IV)
[0021] 273g (1,8 Mol) menthadienol and 377g (1,8 Mol) divarinic acid methylester are dissolved at RT in 1.450g toluene (2.300mL solution A), likewise, an adequate amount of borontrifluoride*etherate are dissolved in 540g toluene at RT (710mL solution B). Solution A and solution B are pumped into a stirred reaction chamber via two separate dosing pumps, from the reaction chamber the reaction composi- tion runs via a PTFE hose into a stirred solution of 1,000 g of sodium bicar- bonate. The total reaction time is about 25 mins. After termination of the metering the hydrolyzed reaction solution is stirred for about 1 hour. Then the hydrolyzed reaction solution is transferred into a 5L jacket reaction vessel, the aqueous phase is separated. The not reacted divarinic acid ester is extracted by six times adding 1.000g of 1% aqueous sodium hydroxide solution. After acidifying with semi conc. sulfuric acid and re-extraction of this aqueous phase, ca. 30% (130 g) of non converted divarinic acid ester are recovered. In the toluene phase, about 320g cannabidivarinic acid methylester (V) are con- tamed, which corresponds to a theoretical yield of 50%. This first intermediate serves as starting material for the following transesterification. Step 2: Transesterification step: OH 0 OH 0 OH : .......I (V) (VI) 2o The toluene is removed in vacuo and to the remaining first intermediate 650 g of ethylene glycol are added under stirring followed by a solution of 122 g of potas- sium hydroxide in 420 g ethylene glycol. A vacuum of ca. 0.5 bar is applied and it is heated to 100-120 C for 2 h, whereby ca. 40 g of methanol distill off. The resulting product composition mainly comprises 2-hyd roxy- ethyl- cannabidivarinolat (VI).
[0022] Step 3: Saponification / Decarboxylation: OH 0 OH LUOH 41111 ..!7* HO >4 HO (VI) (VII) Subsequently, the temperature is increased to 150 C and it is stirred at this temperature for 3-4h (also in vacuo; cfl. step 2). The product composition result- ing from the transesterification is cooled down to ca. 40 C and 1.500 g of water as well as 800 g of methyl-tert. butyether are added and ca. 180 g of semi conc. sulfuric acid are added for neutralization. After phase separation, the solvent is removed using a rotary evaporator and the remainder is distilled over a thin- film io .. evaporator using a vacuum of ca. 1 mbar and a jacket temperature of 230 C. 270 g of cannabidivarin (VII) are obtained in the form of a viscous, yellowish oil with a purity of 85%, which corresponds to a theoretical yield of 85% in relation to the used cannabivarinic acid ester. This viscous, yellowish oil is then recrystallized in ca. 270 g of n-heptane at ca. 10 C, after which 190 g of white to lightly yellow crystallizate with a purity of 99% cannabidivarin (VII) are obtained. Step 4: Cyclization to tetrahydrocannabivarin (THCV): 50 g of pure cannabidivarin (VII) are dissolved in 250 g methylene chloride and 40 g of boron trifluoride*ether complex are added under stirring within 10 min at ca. 22 C. It is stirred for 20 mins at said temperature and then 200 g of ice water are added, the organic phase is washed with sodium bicarbonate solution and the solvent is removed using a rotary evaporator. The remaining raw material of ca. 50 g contains 74% trans-(-)-delta-9-tetrahydrocannabivarin (VIII) and 26% of side products.
[0023] Example 3: Purification of a raw product as obtained in example 1: Any steps described herein were conducted in an inert gas atmosphere (argon) due to the air-sensitivity of the dronabinol. After processing the reaction mixture, the following composition of the raw product is obtained: HPLC-Analysis: (DAD, in Area-%) substance ¨ batch number LN 703795 LN 703814 LN 703842 olivetol (2,8 min) 1,2% 1,3% 1,2% cannabidiol (8,5 min) 0,3% 0,4 % 0,4 % dronabinol (14,8 min) 71,6 % 71,4 % 72,1 % _ 6,9(11)-tetrahydrocannabinol (15,6 min) 0,4 % 0,4 % 0,4 % _ 6,8-tetrahydrocannabinol (17,0 min) 26,3 % 26,3 % 25,4 % _ Figure 3 shows the exemplary chromatogram of LN 703795. The chromatographic system is based on a known SMB apparatus of the com- pany Knauer (Germany). The system comprises 8 separation columns (Knauer Vertex Plus, 250 x 8 mm), as well as the required pumps. The column configura- tion corresponds to the standard 2 ¨ 2 ¨ 2 ¨ 2 arrangement. The movement of the individual columns is implemented by a 64 port rotary valve. The switching time of the valve is 10.81 seconds. The valve and the HPLC columns are located in a tempered column oven. The temperature of the chromatographic system is to 60 C, preferably 30 C. 15 A solid phase suitable for the separation is an RP material (Eurospher ll silica gel, C18P) with a grain size of 10 to 100 pm, preferably 20 to 45 pm. The solid phase showed no signs of deterioration over a time period of two years. This is a further advantage compared to classical chromatographic systems. As mobile (liquid) phase / eluant a mixture of methanol, tetrahydrofuran and 20 water is used, preferably with the composition: methanol (62%), tetrahydofuran
[0024] (17%), water (21%). Furthermore, 0.01% ascorbic acid is added to the mixture as antioxidant. The feed mixture comprises the above described raw product dissolved in eluant mixture at a concentration of 12.5 g/L. The eluant, extract and raffinate pump .. each have a maximum flow rate of 50 ml/min, the feed pump a maximum flow rate of 10 ml/min. In the process described herein, the following flow rates are used: eluant pump (zone 1; 4.4 ml/min), extract pump (zone 2, 3.2 ml/min), raffi- nate pump (zone 4, 1.3 ml/min) and feed pump (zone 3, 0.2 ml/min). The flow rates are measured with a Humonics Optiflow 520. io The supply of the system with eluant and feed solution is done from suitable stock containers, which are secured for fire safety. Eluant and feed solution are periodically overlaid with argon to keep oxygen from the air out. Before entering the system, eluant and feed solution are pumped though a deaerator. The SMB process does not need a constant supervision. The process described herein may be run continuously over several weeks without changing the pa- rameters and without having a change in the yield. The particular stability of the process allows a 24 hour operation, without needing shift workers. Internal con- trols of the process are performed once a day. With the process described herein, 0.15 g/ hour of dronabinol can continuously be obtained from the raffinate. This corresponds to a daily rate of 3.6 g. By upscaling the process from 8 mm to 50 mm columns, the daily yield can be increased to 144 g of pure dronabinol. This corresponds to a yearly production of about 40 kg of dronabinol. The raffinate derived from the SMB process has the following composition: HPLC-Analysis: raffinate (DAD, in Area-%)
[0025] substance ¨ batch number LN 703795 LN 703814 LN 703842 olivetol 1,1% 1,1% 1,4% cannabidiol 0,4 % 0,2 % 0,4 % dronabinol >97 % >97 % >97 % 6,9(11) - tetrahydrocannabinol n.d. n.d. n.d. 6,8 - tetrahydrocannabinol n.d. n.d. n.d. n.d. = not detectable Figure 4 shows the exemplary chromatogram of the raffinate from LN 703795. After adjusting the adsorption equilibrium, the obtained raffinate is subjected to further processing. The solvent is reduced by distillation (100 mbar vacuum at a temperature of 30 C) to 30 % organic. The distilled solvent is reintroduced to the process as eluant after adjustment of the starting mixture. The obtained reduced raffinate is extracted twice with cyclohexane (50 wt.-% with respect to the re- duced raffinate). The olivetol contained in the raffinate stays in the water/organic phase, while the dronabinol passes into the cyclohexane phase. After removal of the solvent by distillation, dronabinol is obtained with a content of > 99% at a residual solvent content of below 100 ppm. HPLC-Analysis: final product (DAD, in Area-%) substance ¨ batch number LN 703795 LN 703814 LN 703842 olivetol n.d. n.d. n.d. cannabidiol 0.31 % 0.51 % 0.41 % dronabinol 99.34 % 98,10 % 99.15 % 6,9(11) - tetrahydrocannabinol n.d. n.d. n.d. 6,8 - tetrahydrocannabinol n.d. n.d. n.d. n.d. = not detectable
[0026] Figure 5 shows the exemplary chromatogram of the final product from LN 703795. For extraction, instead of cyclohexane, a plant oil based on a mixture of medium chain triglyceride may alternatively be used. This leads to a comparable purity as obtained with cyclohexane and a stable storage medium for the pure compound. Short description of the drawings: Fig. la) shows the preparative HPLC purification of 25 mg raw product obtained in the synthesis according to EP 2842933 B1, wherein the two peaks are dronabinol as main product (larger peak) and delta-8-THC as main impurity io (smaller peak). Fig. 1 b) shows the preparative HPLC purification of 200 mg raw product obtained in the synthesis according to EP 2842933 B1 comprising dronabinol as main product and delta-8-THC as main impurity, which can not be resolved in this quantity. Figs. 2a) and b) show a schematic setup of a SMB system. Figure 3 shows the exemplary chromatogram of LN 703795. Figure 4 shows the exemplary chromatogram of the raffinate from LN 703795. Figure 5 shows the exemplary chromatogram of the final product from LN 703795.
Cannabidiol synthesis method
CN106810426
The invention provides a cannabidiol synthesis method. The method
includes: taking 2,4-dyhydroxy-6-pentyl methyl benzoate as a raw
material, and subjecting to ester exchange with N,N-dialkyl
alcohol amine under potassium hydroxide catalysis; subjecting to
coupled reaction with (1S,
4R)-1-methyl-4-(1-methylvinyl)-2-cyclohexene-1-alcohol under Lewis
acid catalysis; performing acid-base extraction and
recrystallization to obtain a high-purity key intermediate
product; subjecting to hydrolysis decarboxylation to obtain crude
cannabidiol, and subjecting the crude cannabidiol to once
recrystallization to obtain cannabidiol according with raw
medicine quality requirements. The cannabidiol synthesis method
has advantages that raw materials and reagents are cheap and
commercially easy to acquire, the total yield of the finally
prepared raw medicine in qualified purity reaches 35-40%, the
process is improved evidently, and the method has a promising
industrial application prospect.CN106810426
The present invention provides a transesterification of N,N-dialkylolamine catalyzed by potassium hydroxide with 2,4-dihydroxy-6-pentyl benzoic acid methyl ester as a raw material, and then The coupling reaction of 1S,4R)-1-methyl-4-(1-methylvinyl)-2-cyclohexene-1-ol is catalyzed by Lewis acid, and is obtained by acid-base extraction and recrystallization. The key intermediate product of purity is hydrolyzed and decarboxylated to obtain crude cannabisdiol. The crude product can be recrystallized at one time to obtain cannabisdiol which meets the quality requirements of the drug substance. The raw materials and reagents in the method of the invention are low in price and commercially available, and the total yield of the qualified raw materials obtained in the final method is up to 35-40%, and the process is obviously improved, which has a good industrial application prospect.
Background technique
Cannabinoids are distinguished from L-trans- cannabinol, English name (-)-Cannabidiol, which is a very marketable drug substance. The structural formula of this compound is:
[image]
Currently, cannabidiol is mainly used to protect nerves, anti-caries, anti-inflammatory and anti-anxiety effects. 2015GW Biopharmaceuticals announced that it has updated its clinical trial data on pure cannabinol for refractory childhood epilepsy. In 2014, the drug has been approved by the US FDA for rare diseases and fast-track approval for the treatment of infants. Myoclonic epilepsy, which makes the market prospects for this drug more widespread. It is cheap, efficient and easy to operate. It is suitable for the industrial synthetic production process and will greatly promote the application of cannabidiol.
US20090036523A1 uses olive alcohol as a starting material and is catalyzed by p-toluenesulfonic acid to obtain the target product in one step, as follows:
[image]
However, the reaction system is complicated, and there are many isomers and dimers, and the post-treatment is troublesome. It requires column chromatography purification and the yield is low, only 24%, which is not suitable for scale-up production.
WO2006053766A1 utilizes zinc chloride to catalyze the synthesis of the target product. This document reports a process for obtaining a product without column purification, but the purity of the product is only 97.1%, and the yield is only 22%. We repeated the test on the literature and found that the largest single impurity in the reaction process is dimer, which is more than 20%. The impurity needs to be crystallized more than 3 times to fall within 0.1% (to meet the requirements of API). When the qualified API is finally obtained, the total yield is only 13%, and the process cost is high.
US20100298579A1 is prepared by using methyl 2,4-dihydroxy-6-pentanylbenzoate as a starting material and catalyzed by boron trifluoride diethyl ether to prepare a coupled methyl ester intermediate (I). The purity of the reaction is one step. Slightly higher, isomers and dimers are also significantly less than one-step. However, after the coupling, the methyl ester intermediate is still only about 75% pure after acid-base treatment, and the melting point of the compound may be low and cannot be crystallized (intermediate I has not been reported as melting point, even if the purity of the column is 98. % of the intermediate I was crystallized and eventually could not be precipitated as a solid). The methyl ester intermediate I cannot be recrystallized and purified by a conventional method, so that the chemical purity and the single impurity index requirement as key intermediates of the drug substance cannot be achieved.
[image]
In addition to the above two chemical synthesis methods, there are some reports that can be obtained by biological extraction of cannabidiol, but such method steps are cumbersome, and industrial production limitations are too large.
Summary of the invention
The object of the present invention is to solve the above technical problems and to provide a method for synthesizing cannabidiol.
The object of the invention is achieved by the following technical solutions:
A method for synthesizing cannabidiol, the reaction formula of which is as follows
[image]
Including the following steps:
S1, using 2,4-dihydroxy-6-pentylbenzoic acid methyl ester as a raw material, transesterifying with N,N-dialkylolamine under the action of potassium hydroxide to obtain intermediate one; the intermediate Wherein n is 1 to 8, and R is any one of a methyl group, an ethyl group, a propyl group and a butyl group;
S2, an intermediate prepared by coupling an intermediate 1 obtained in S1 with (1S,4R)-1-methyl-4-(1-methylvinyl)-2-cyclohexen-1-ol to prepare an intermediate 2; in the intermediate two, n = 1 to 8, and the R is any one of a methyl group, an ethyl group, a propyl group and a butyl group;
S3, the obtained intermediate 2 is hydrolyzed and decarboxylated under the action of sodium hydroxide to finally obtain cannabidiol.
Preferably, the S1 comprises the following steps:
S11, using 2,4-dihydroxy-6-pentylbenzoic acid methyl ester as a raw material and N,N-dialkylolamine, under the action of potassium hydroxide, reacting by nitrogen gas;
S12, performing the first extraction by adding an acid solution to adjust the pH of the solution to acidity;
S13, adjusting the pH of the solution to be alkaline by adding a base, and performing re-extraction;
S14, washed with water, dried, and concentrated under reduced pressure to give Intermediate 1.
Preferably, the pH of the solution is adjusted to 2-3 in the S12.
Preferably, the pH of the solution is adjusted to 10 in the S12.
Preferably, the pH is adjusted in the S13 by the addition of a basic solid.
Preferably, the alkaline solid is added to the S13 as an aqueous sodium carbonate solid. Of course, the adjustment of the alkaline alkali solid or the solution can be, the solid is added to avoid too much water consumption of the alkali, sodium carbonate, potassium carbonate, cesium carbonate, sodium hydroxide, potassium hydroxide and other conventional bases can be.
Preferably, the S2 comprises the following steps:
S21, intermediate one and (1S, 4R)-1-methyl-4-(1-methylvinyl)-2-cyclohexen-1-ol are condensed under the catalysis of anhydrous zinc chloride;
S22, after the reaction is completed, the acid is added, and the crude product of the recrystallizable intermediate 2 having a purity of at least 90% is purified by an acid-base extraction method;
S23, the crude product of the intermediate 2 is synthesized by solvent recrystallization to synthesize the high-purity key intermediate 2 of the bulk drug.
Preferably, the acid in the S22 is any one of hydrochloric acid, sulfuric acid, acetic acid, oxalic acid and citric acid.
Preferably, the solvent shown in S23 is any one of petroleum ether, n-pentane, n-hexane and n-heptane.
Preferably, the purity of the cannabidiol produced by the above method is from 99.88% to 99.98%.
The invention has the beneficial effects that the raw materials and reagents in the method of the invention are low in price and commercially available, and high-quality cannabisdiol can be obtained through a three-step reaction of transesterification, coupling and decarboxylation. Although the step of the process is increased to 3 steps, the intermediate of each step can be purified by recrystallization, and the single impurity can reach the intermediate index of the raw material medicine, and the total yield of the qualified raw material medicine can be up to 35~. 40%, the process is obviously improved, and it has a good industrial application prospect.
Detailed ways
The method of the present invention will be described below by way of specific embodiments to make the technical solution of the present invention easier to understand and grasp, but the present invention is not limited thereto. The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.
In the embodiment used in the present invention, when pH is adjusted, sodium carbonate is used in the present application, but it is not limited thereto, and a conventional base such as potassium carbonate, cesium carbonate, sodium hydroxide or potassium hydroxide may be used. Other regulatory auxiliary agents can also be replaced by other conventional means.
Embodiment 1
Preparation of intermediate one:
First, 119 g of methyl 2,4-dihydroxy-6-pentanebenzoate and 89 g of N,N-dimethylethanolamine were placed in a 250 mL three-necked flask, and 30.8 g of potassium hydroxide was added thereto with stirring to protect the nitrogen gas. The temperature was raised to 130 ° C and the reaction was stirred for 4 hours. The reaction solution was cooled to below 30 ° C, adjusted to pH 2-3 with 1N aqueous hydrochloric acid solution, and extracted with n-heptane (250 mL×2). The aqueous sodium carbonate solid was adjusted to pH 10, and n-heptane (250 mL×2) was added. The extract was washed with water (150 mL), dried over anhydrous sodium sulfate, and evaporated to dryness.
Preparation of intermediate 2:
100 g of the above transesterified pure product and 800 mL of dichloromethane were placed in a 2000 mL three-necked flask, and 50.8 g of zinc chloride, 8 g of water were added under stirring, and stirred at 25 ° C for 0.5 hour, and 46.4 g of (1S, 4R) was added dropwise. -1-Methyl-4-(1-methylvinyl)-2-cyclohexen-1-ol, the system is basically not exothermic, and the mixture is kept warm and stirred for 24 hours after the completion of the dropwise addition. The reaction solution was cooled to below 10 ° C, adjusted to pH 2-3 with 1N aqueous hydrochloric acid solution, and extracted with n-heptane (500 mL×2). The aqueous sodium carbonate solid was adjusted to pH 10, and n-heptane (500 mL×2) was added. The extract was washed with water (300 mL), dried over anhydrous sodium sulfate and evaporated. The crude product was added to 4v/m n-heptane at 40 ° C for heating and dissolution, and the temperature was lowered to -5 to 5 ° C for crystallization for 16 hours. After suction filtration and drying, 60.2 g of a white solid was obtained, yield 46%, HPLC purity 99.98%. .
Synthesis of cannabidiol:
Add 50g of the above coupled product and 250mL of methanol to a 1000mL three-necked flask, add 5v/m 3N sodium hydroxide aqueous solution under nitrogen protection, heat up to 95 °C, keep the reaction for 8 hours, cool down to 25 °C, add Zhenggeng The alkane (200 mL*2) was extracted, and the combined organic phases were washed once with 100 mL of saturated sodium chloride, concentrated to dryness under reduced pressure, and then recrystallized from 4 v/m n-heptane, and incubated at -5 to 5 ° C for 16 hours. After filtration and drying, 33.7 g of a white solid was obtained with a yield of 92% and HPLC purity 99.93%.
Embodiment 2
Preparation of intermediate one:
119 g of methyl 2,4-dihydroxy-6-pentanebenzoate and 234 g of N,N-dimethylbutanolamine were placed in a 500 mL three-necked flask, and 33.6 g of potassium hydroxide was added thereto with stirring to protect the nitrogen gas. The temperature was raised to 130 ° C and the reaction was stirred for 4 hours. The reaction solution was cooled to below 30 ° C, adjusted to pH 2-3 with 1N aqueous hydrochloric acid solution, and extracted with n-heptane (250 mL×2). The aqueous sodium carbonate solid was adjusted to pH 10, and n-heptane (250 mL×2) was added. The extract was washed with water (150 mL), dried over anhydrous sodium sulfate, and evaporated to dryness, and then evaporated to dryness.
Preparation of intermediate 2:
100 g of the above transesterified pure product and 800 mL of dichloromethane were placed in a 2000 mL three-necked flask, and 46.4 g of zinc chloride, 7.3 g of water were added thereto with stirring, and stirred at 25 ° C for 0.5 hour, and 42.4 g of (1S, 4R) was added dropwise. )-1-methyl-4-(1-methylvinyl)-2-cyclohexen-1-ol, the system is basically not exothermic, and the mixture is kept warm and stirred for 24 hours after the dropwise addition. The reaction solution was cooled to below 10 ° C, adjusted to pH 2-3 with 1N aqueous sulfuric acid solution, and extracted with n-heptane (500 mL×2). The aqueous sodium carbonate solid was adjusted to pH 10, and n-heptane (500 mL×2) was added. The extract was washed with water (300 mL), dried over anhydrous sodium sulfate and evaporated. The crude product was added to 4v/m petroleum ether and dissolved by heating at 40 ° C, and the temperature was lowered to -5 to 5 ° C for crystallization for 16 hours. After suction filtration, it was dried to obtain 53.5 g of a white solid, yield 42%, HPLC purity 99.98%.
Synthesis of cannabisdiol:
Add 50g of the above coupled product and 250mL of methanol to a 1000mL three-necked flask, add 5v/m 3N sodium hydroxide aqueous solution under nitrogen protection, heat up to 95 °C, keep the reaction for 8 hours, cool down to 25 °C, add Zhenggeng The alkane (200 mL*2) was extracted, and the combined organic phases were washed once with 100 mL of saturated sodium chloride, concentrated to dryness under reduced pressure, and then recrystallized from 4 v/m n-heptane, and incubated at -5 to 5 ° C for 16 hours. After filtration and drying, 31.3 g of a white solid was obtained with a yield of 91% and HPLC purity 99.95%.
Embodiment 3:
Preparation of intermediate one:
119 g of methyl 2,4-dihydroxy-6-pentanebenzoate and 145 g of N,N-dimethylhexanolamine were placed in a 250 mL three-necked flask, and 30.8 g of potassium hydroxide was added thereto with stirring to protect the nitrogen gas. The temperature was raised to 130 ° C and the reaction was stirred for 4 hours. The reaction solution was cooled to below 30 ° C, adjusted to pH 2-3 with 1N aqueous hydrochloric acid solution, and extracted with n-heptane (250 mL×2). The aqueous sodium carbonate solid was adjusted to pH 10, and n-heptane (250 mL×2) was added. The extract was washed with water (150 mL), dried over anhydrous sodium sulfate, and evaporated to dryness, and then evaporated to dryness, and then, then,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Preparation of intermediate 2:
100 g of the above transesterified pure product and 800 mL of dichloromethane were placed in a 2000 mL three-necked flask, and 43.8 g of zinc chloride, 6.9 g of water was added under stirring, and stirred at 25 ° C for 0.5 hour, and 40 g of (1S, 4R) was added dropwise. -1-Methyl-4-(1-methylvinyl)-2-cyclohexen-1-ol, the system is basically not exothermic, and the mixture is kept warm and stirred for 24 hours after the completion of the dropwise addition. The reaction solution was cooled to below 10 ° C, adjusted to pH 2-3 with 1N aqueous sulfuric acid solution, and extracted with n-heptane (500 mL×2). The aqueous sodium carbonate solid was adjusted to pH 10, and n-heptane (500 mL×2) was added. The extract was washed with water (300 mL), dried over anhydrous sodium sulfate and evaporated. The crude product was added to 4 v/m of n-hexane at 40 ° C to dissolve by heating, and the temperature was lowered to -5 to 5 ° C for crystallization for 16 hours. After suction filtration and drying, 58.5 g of a white solid was obtained, yield 47%, HPLC purity 99.91%.
Synthesis of cannabisdiol:
Add 50g of the above coupled product and 250mL of methanol to a 1000mL three-necked flask, add 5v/m 3N sodium hydroxide aqueous solution under nitrogen protection, heat up to 90 °C, keep the reaction for 4 hours, cool down to 25 °C, add Zhenggeng The alkane (200 mL*2) was extracted, and the combined organic phases were washed once with 100 mL of saturated sodium chloride, concentrated to dryness under reduced pressure, and then recrystallized from 4 v/m n-heptane, and incubated at -5 to 5 ° C for 16 hours. After filtration and drying, 30.4 g of a white solid was obtained, yield 94%, HPLC purity 99.88%.
Embodiment 4:
Preparation of intermediate one:
119 g of methyl 2,4-dihydroxy-6-pentanebenzoate and 145.3 g of N,N-dipropylethanolamine were placed in a 250 mL three-necked flask, and 30.8 g of potassium hydroxide was added thereto under stirring to protect with nitrogen. The temperature was raised to 130 ° C and the reaction was stirred for 4 hours. The reaction solution was cooled to below 30 ° C, adjusted to pH 2-3 with 1N aqueous hydrochloric acid solution, and extracted with n-heptane (250 mL×2). The aqueous sodium carbonate solid was adjusted to pH 10, and n-heptane (250 mL×2) was added. The extract was washed with water (150 mL), dried over anhydrous sodium sulfate, and evaporated to dryness, and then evaporated to dryness, and then, then,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Preparation of intermediate 2:
100 g of the above transesterified pure product and 800 mL of dichloromethane were placed in a 2000 mL three-necked flask, and 43.8 g of zinc chloride, 6.9 g of water was added under stirring, and stirred at 25 ° C for 0.5 hour, and 40 g of (1S, 4R) was added dropwise. -1-Methyl-4-(1-methylvinyl)-2-cyclohexen-1-ol, the system is basically not exothermic, and the mixture is kept warm and stirred for 24 hours after the completion of the dropwise addition. The reaction solution was cooled to below 10 ° C, adjusted to pH 2-3 with 1N aqueous sulfuric acid solution, and extracted with n-heptane (500 mL×2). The aqueous sodium carbonate solid was adjusted to pH 10, and n-heptane (500 mL×2) was added. The extract was washed with water (300 mL), dried over anhydrous sodium sulfate and evaporated. The crude product was added to 4 v/m of n-heptane at 40 ° C to dissolve by heating, and the temperature was lowered to -5 to 5 ° C for crystallization for 16 hours. After suction filtration and drying, 51 g of a white solid was obtained, yield 41%, HPLC purity 99.86%.
Synthesis of cannabisdiol:
Add 50g of the above coupled product and 250mL of methanol to a 1000mL three-necked flask, add 5v/m 3N sodium hydroxide aqueous solution under nitrogen protection, heat up to 95 °C, keep the reaction for 8 hours, cool down to 25 °C, add Zhenggeng The alkane (200 mL*2) was extracted, and the combined organic phases were washed once with 100 mL of saturated sodium chloride, concentrated to dryness under reduced pressure, and then recrystallized from 4 v/m n-heptane, and incubated at -5 to 5 ° C for 16 hours. After filtration and drying, 28.5 g of a white solid was obtained, yield 88%, HPLC purity 99.97%.
There are many specific embodiments of the invention. All technical solutions formed by equivalent replacement or equivalent transformation are within the scope of the claimed invention.