CN113372196B

CN113372196B - 8, 9-dihydrocannabidiol and synthesis method and application thereof

Info

Publication number: CN113372196B
Application number: CN202110753461.6A
Authority: CN
Inventors: 夏咏梅; 吴淇; 邹亮华; 郭茂岳; 胡学一; 方云
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2021-07-02
Filing date: 2021-07-02
Publication date: 2022-09-30
Anticipated expiration: 2041-07-02
Also published as: CN113372196A

Abstract

The invention discloses 8, 9-dihydrocannabidiol and a synthesis method and application thereof, belonging to the field of organic synthesis. The invention takes alpha-phellandrene and olivetol as substrates, and 8, 9-dihydrocannabidiol is obtained by reaction under the action of Lewis acid catalyst. The method has the advantages of cheap raw materials, cheap and easily-separated catalyst (removed by filtration), small usage amount (0.9 percent of the mass of the reaction substance), mild reaction (Lewis acid), high yield (90 percent), greatly reduced industrial cost and simple operation.

Description

8, 9-dihydrocannabidiol and synthesis method and application thereof

Technical Field

The invention belongs to the technical field of organic synthesis, and particularly relates to 8, 9-dihydrocannabidiol and a synthesis method and application thereof.

Background

Natural compounds extracted from the cannabis plant have a variety of biological activities, including bacteriostatic activity and the like. The cannabis plant contains over 500 chemical species including approximately 100 cannabinoids and various other terpenes, phenols, lipids, flavonoids and steroids, among which tetrahydrocannabinol (THC, which has hallucinogenic effects on the human body and causes adverse symptoms such as accelerated heartbeat, sleepiness, dry mouth and bulimia) and cannabidiol (CBD, which has been approved in the united states for use in food and cosmetics) are the two leading cannabinoids present in the cannabis plant. However, CBD is still not approved for use in many countries, including china, because it can be converted to THC, a drug, by chemical means.

8, 9-dihydrocannabidiol (H2CBD) can be obtained by a synthetic method, has the effect equivalent to that of CBD, but cannot be converted into THC in vivo or by other chemical means, so that the anesthetic effect and other hazards of THC can not be caused to human bodies. In addition, H2CBD has the following advantages over CBD: the H2CBD has better safety and is not a controlled substance, so that the H2CBD is not prohibited by law and can be popularized and applied in more countries and regions; CBD must be obtained separately from a mixture containing hundreds of other extracts and it may be contaminated with pesticides, whereas the process of obtaining H2CBD by synthetic methods is simpler and the product is more easily obtained in pure form. In addition to the potential antidepressant action, the use of 8, 9-dihydrocannabidiol (H2CBD) in other areas is not yet developed.

The existing method for synthesizing 8, 9-dihydrocannabidiol is obtained by catalytic reaction of alpha-phellandrene and olive alcohol at room temperature in the presence of benzene as a solvent and a strong-acid catalyst (p-toluenesulfonic acid monohydrate), and the reaction mechanism of the reaction is as follows: the alpha-phellandrene is protonated to form a carbenium ion which attacks the benzene ring structure of the olivine and completes Friedel-crafts reaction with the benzene ring structure. Two products are formed due to the presence of two active sites on the olivetol phenyl ring structure, ortho and para to the pentyl group. The strong acid catalyst has high catalytic efficiency theoretically, but has high corrosion to equipment. Under this synthesis, the formation of partially cyclized product occurs simultaneously, with the following main reactions and by-products:

by-products:

therefore, the reaction specificity of the p-toluenesulfonic acid monohydrate catalyst is poor, and the separation and purification of a target compound are difficult. And the amount of the catalyst used in the synthesis method is large (30% of the mole of the reactants), so that a method for catalytically synthesizing 8, 9-dihydrocannabidiol by using a small amount of mild catalyst is needed to be developed.

Therefore, a weak acid Lewis acid catalyst is urgently needed to be found, and 8, 9-dihydrocannabidiol is effectively synthesized through the synergistic effect of process factors. And the use of 8, 9-dihydrocannabidiol in anti-depression applications is developed.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a new synthesis method of 8, 9-dihydrocannabidiol, so as to solve the problem of large catalyst dosage in the existing synthesis method of 8, 9-dihydrocannabidiol.

In order to solve the technical problems, the invention provides the following technical scheme:

the invention provides a method for synthesizing 8, 9-dihydrocannabidiol, which comprises the following steps:

in an organic solvent, reacting alpha-phellandrene with olivetol under the action of a Lewis acid catalyst to obtain the 8, 9-dihydrocannabidiol;

further, the reaction synthetic route is as follows:

further, the organic solvent includes one or more of toluene, xylene, ethyl acetate, and acetone.

Furthermore, the addition amount of the organic solvent is 2.8-5.6L/kg based on the mass of the olive alcohol.

Further, the Lewis acid catalyst is one or more of aluminum trichloride, boron trifluoride monohydrate, boron trifluoride diethyl etherate, ferric trichloride hexahydrate, ferric trichloride, ferric bromide, stannic chloride and cupric chloride dihydrate.

Further, the Lewis acid catalyst is one or more of aluminum trichloride, boron trifluoride monohydrate, boron trifluoride diethyl etherate, ferric trichloride hexahydrate and ferric trichloride.

Furthermore, the dosage of the Lewis acid catalyst is 0.45-0.9 percent of the mass of the olive alcohol.

Furthermore, the molar ratio of the alpha-phellandrene to the olive alcohol is (1.0-1.25): 1.0.

Further, the temperature of the reaction is 15-75 ℃.

Further, the reaction time is 0.1-1.0 h.

The invention also provides 8, 9-dihydrocannabidiol prepared by the synthesis method.

The 8, 9-dihydrocannabidiol is applied to preparing a bacteriostatic agent.

The 8, 9-dihydrocannabidiol is applied to the preparation of bactericides.

Further, the strain is escherichia coli and staphylococcus aureus.

Further, the product is isolated and purified: according to TLC monitoring, after ensuring the raw material reaction is complete, filtering, taking filtrate, washing with saturated saline solution for 3-5 times, distilling under reduced pressure to remove solvent to obtain crude product, separating the crude product by silica gel column chromatography, eluting with mixed solution of petroleum ether and ethyl acetate (petroleum ether: ethyl acetate: 40:1), performing TLC elution tracking detection, collecting eluent containing target product, combining the target product eluent, and evaporating and concentrating to obtain 8, 9-dihydrocannabidiol.

Further, the product can be separated and purified by filtering the reaction solution to recover the catalyst and washing with water to remove the residual catalyst in the reaction solution.

Compared with the prior art, the invention has the beneficial effects that:

compared with the existing synthesis method of 8, 9-dihydrocannabidiol catalyzed by p-toluenesulfonic acid, the synthesis method has the advantages that the catalyst is cheap and easy to obtain, strong acid is not needed, the catalyst can be filtered and recycled, the using amount of the catalyst is reduced from 0.3 equivalent of the mole number of reactants in the catalysis process of p-toluenesulfonic acid to 0.01 equivalent (namely 1 percent of the mole number of the reactants), and the industrial cost is greatly reduced; and the catalytic activity is good, the product yield can reach 90%, the reaction specificity to the target compound is good, and the separation and purification are facilitated.

Drawings

In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the present disclosure taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows the preparation of 8, 9-dihydrocannabidiol in example 1 of the present invention ¹ HNMR NMR hydrogen spectrum.

FIG. 2 shows the preparation of 8, 9-dihydrocannabidiol in example 1 of the present invention ¹³ CNMR NMR carbon spectrum.

FIG. 3 is a mass spectrum of 8, 9-dihydrocannabidiol prepared in example 1 of the present invention.

Detailed Description

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In the following examples, the method for quantitative analysis of the synthesized 8, 9-dihydrocannabidiol was:

using detectors equipped with photodiode arraysWas analyzed by HPLC. A30. mu.L sample was injected and separation was achieved using an ACE C18-PFP (150 mm. times.4.6 mm. times.3 μm) column. The mobile phase was acetonitrile-water 62:38 (v/v). The flow rate was set to 1 mL-min ^-1 The column temperature was maintained at 55 ℃. The absorbance of the target compound (H2CBD) was monitored at 220 nm.

Example 1

Olivine (18g, 0.1mol) and α -phellandrene (17g, 0.125mol) were dissolved in toluene (10mL), ferric trichloride (0.162g, 1mmol) was added, the mixture was stirred at room temperature (25 ℃) to react, monitored by TLC and HPLC until the yield of 8, 9-dihydrocannabidiol did not increase any more, filtered, the obtained filtrate was washed with saturated saline (3 × 50mL), the solvent was distilled off under reduced pressure, the crude product was subjected to silica gel column chromatography and eluted with a mixture of petroleum ether and ethyl acetate (petroleum ether: ethyl acetate ═ 40:1), followed by TLC elution. The combined silica gel column eluates containing the desired product were collected and concentrated to give 8, 9-dihydrocannabidiol (28.44g, 90% yield) as a dark yellow oil. The specific NMR hydrogen spectrum and NMR carbon spectrum of the obtained H2CBD are shown in FIG. 1 and FIG. 2 respectively. The specific mass spectrum of the obtained H2CBD is shown in figure 3.

¹ H NMR(400MHz,CDCl ₃ ) Data: δ 6.23(s,3H),5.54(dt, J ═ 2.9,1.7Hz,1H),4.81(s,1H),3.92-3.77(m,1H),2.52-2.43(m,2H),2.22-2.07(m,2H),1.87-1.76(m,4H),1.72-1.56(m,4H),1.38-1.30(m,5H),0.90(dt, J ═ 15.3,6.7Hz,9H). ¹³ C NMR(126MHz,CDCl ₃ )δ142.9,140.0,124.8,114.0,43.7,35.5,31.6,30.7,27.8,24.1,22.6,22.1,21.7,16.4,14.1。GC-MS:m/z(rel int.)：316[M ⁺ ](15％),273(7％),260(6％),246(25％),231(100％),193(10％)。

Examples 2-8, comparative examples 1-2: effect of catalyst on yield

Examples 2-8, comparative examples 1-2 were synthesized in a similar manner to example 1, except that the catalyst used was different. The Lewis acid catalysts used in the examples and comparative examples and the corresponding yields are shown in Table 1.

TABLE 1 catalysts used in examples 1-10 and corresponding yields

	Catalyst and process for preparing same	Yield (%)
			Example 1	Ferric chloride	90
Example 2	Boron trifluoride monohydrate	53
			Example 3	Boron trifluoride diethyl etherate	53
Example 4	Ferric chloride hexahydrate	50
			Example 5	Aluminium trichloride	54
Example 6	Cupric chloride dihydrate	38
			Example 7	Ferric bromide	41
Example 8	Tin chloride	33
			Comparative example 1	Nickel chloride	Trace(<5)
Comparative example 2	Zinc chloride	Trace(<5)

As can be seen from the results in table 1, the synthesis method of the present invention requires the selection of a suitable lewis acid catalyst, and when nickel chloride or zinc chloride is selected as the catalyst, the yield of 8, 9-dihydrocannabidiol is less than 5%; when aluminum trichloride, boron trifluoride monohydrate, boron trifluoride diethyl etherate, ferric trichloride hexahydrate, ferric trichloride, ferric bromide, stannic chloride or cupric chloride dihydrate are selected as catalysts, the yield of 8, 9-dihydro cannabidiol is higher than 30%; wherein, when ferric trichloride is used as the catalyst, the yield of 8, 9-dihydrocannabidiol reaches 90 percent, and the catalyst is the best catalyst.

Example 9: influence of the amount of iron trichloride catalyst on the yield

The synthesis method of example 9 and the synthesis method of comparative example 3 are similar to example 1, except that the amount of the catalyst is different. The amounts of catalyst used and the corresponding yields for each example are shown in table 2.

Table 2 amount of catalyst used in examples 1, 9 and comparative example 3 and corresponding yield

	The amount of ferric chloride (wt%)	Yield (%)
			Example 9	0.45	65
Example 1	0.9	90
			Comparative example 3	4.5	89

As can be seen from the results in Table 2, as the amount of ferric chloride used increases, the yield also increases; when the dosage of ferric trichloride is 0.9%, the yield reaches the highest 90%; the dosage of ferric trichloride is continuously increased, and the product yield is not continuously increased; when the amount of ferric chloride exceeds 4.5%, the yield of 8, 9-dihydrocannabidiol is rather decreased (selectivity is lowered). Therefore, the reaction yield can reach 90% when the dosage of the ferric trichloride catalyst is 1%, and 0.45% -0.9% is an ideal dosage.

Examples 10 to 14: effect of solvent on yield

The synthesis of examples 10-14 is similar to example 1, except that an organic solvent is used. The organic solvents used in the examples and the corresponding yields are shown in table 3.

TABLE 3 organic solvents and corresponding yields for examples 1, 10-14

	Solvent(s)	Yield (%)
			Example 1	Toluene	90
Example 10	Xylene	60
			Example 11	Ethyl acetate	44
Example 12	1, 2-dichloroethane	49
			Example 13	Acetone (II)	40
Example 14	Xylene/toluene	69

As can be seen from the results of table 3, the synthesis reaction of the present invention can use xylene, toluene or a mixture thereof as an organic solvent, wherein toluene is used as the organic solvent, and the yield of 8, 9-dihydrocannabidiol reaches 90%, which is the best organic solvent. The use of ethyl acetate, 1, 2-dichloroethane, acetone, etc. as solvents also allows for appreciable yields.

Example 15: influence of reactant ratio on yield

The synthesis of example 15 is similar to that of example 1, except that a-phellandrene is used in different amounts. The amounts of α -phellandrene used in the examples and the corresponding yields are shown in table 4.

Table 4 amount of alpha-phellandrene used in examples 1 and 15, and comparative examples 4 to 6 and corresponding yield

As can be seen from the results in table 4, when the amount of α -phellandrene is less than 1.25 equivalents, the yield of 8, 9-dihydrocannabidiol increases with the increase in the amount of α -phellandrene; when the amount of α -phellandrene is more than 2 equivalents, the yield of 8, 9-dihydrocannabidiol is rather decreased as the amount of α -phellandrene is increased. Wherein, when the dosage of the alpha-phellandrene is 1.25 equivalents, the reaction yield reaches 90 percent, which is the optimal dosage.

Example 16: effect of substrate concentration on yield

Example 16, comparative examples 7 and 8 were synthesized in a similar manner to example 1, except that toluene was used in a different amount. The amount of toluene used in each example and the corresponding yield are shown in Table 5.

TABLE 5 amount of toluene used and corresponding yield for examples 1 and 16, comparative examples 7 and 8

	Amount of toluene used (mL/g)	Yield (%)
			Example 16	2.8	85
Example 1	5.6	90
			Comparative example 7	8.4	88
Comparative example 8	11.2	87

From the results of table 5, it is understood that the amount of toluene used as an organic solvent has a certain influence on the yield of 8, 9-dihydrocannabidiol. When the dosage of the toluene relative to the olive alcohol is less than 5.6mL/g, the increase of the dosage of the toluene has a certain effect on improving the yield of the 8, 9-dihydrocannabidiol. When the dosage of the toluene relative to the olive alcohol exceeds 5.6mL/g, the yield of the 8, 9-dihydrocannabidiol is reduced along with the increase of the dosage of the toluene. Therefore, when the using amount of the organic solvent is 2.8-5.6mL/g, the reaction has better product yield and production intensity.

Example 17: effect of reaction time on yield

The synthesis method of example 17 and the synthesis method of comparative example 9 are similar to example 1, except that the reaction time is different. The reaction time and the corresponding yield of each example are shown in table 6.

TABLE 6 reaction times and corresponding yields for examples 1 and 17 and comparative example 9

	Reaction time (h)	Yield (%)
			Example 17	0.5	67
Example 1	1.0	90
			Comparative example 9	1.5	90

From the results in Table 6, it is understood that the reaction time has a certain influence on the reaction yield, and that the yield of 8, 9-dihydrocannabidiol is not lower than 67% at the reaction time of 0.5 to 5 hours. Wherein, when the reaction time is 1-2h, the yield of the 8, 9-dihydrocannabidiol can reach 90%. Therefore, the reaction time of 1-1.5h is a relatively ideal reaction time.

Application example

The H2CBD prepared in example 1 was tested for Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) against e.coli, staphylococcus aureus.

Taking a sterile 96-well plate, adding 100 mu L of LB liquid culture medium into each of the 1 st to 10 th wells, adding 100 mu L of H2CBD ethanol solution of 200 mu g/mL into the 1 st well, fully mixing uniformly, sucking 100 mu L, adding into the 2 nd well, diluting to the 10 th well in series by the same method twice, enabling the drug concentration to be from 100 mu g/mL to 0.2 mu g/mL, adding bacterial diluent diluted to the concentration of 106CFU/mL by the LB liquid culture medium into the 1 st to 10 th wells of 100 mu L, and simultaneously setting a negative control (adding 100 mu L of ethanol into the 11 th well, 100 mu L of bacterial liquid into the 11 th well), a blank control (only adding 200 mu L of LB liquid culture medium into the 12 th well) and tetracycline hydrochloride, gentamicin, ofloxacin and chloramphenicol as positive controls. 3 parallel controls are set, the culture is carried out in a constant temperature incubator at 37 ℃ for 24 hours, and the bacteria-free growth in the lowest concentration hole of the medicine is observed by naked eyes, namely the MIC of the tested bacteria. And inoculating the drug-containing bacterial liquid without bacterial growth in the holes to an LB solid culture medium, and continuously culturing for 24 hours in a constant-temperature incubator at 37 ℃, wherein the minimum concentration without bacterial growth is the MBC of the tested bacteria. The results are shown in tables 7 to 8.

TABLE 7H 2CBD and minimum inhibitory concentration (μ g/mL) for E.coli, Staphylococcus aureus

TABLE 8H 2CBD and minimum bactericidal concentration (μ g/mL) for E.coli, Staphylococcus aureus

From the results in tables 7-8, it can be seen that the H2CBD has the same bacteriostatic activity as CBD, and compared with the common antibiotics such as tetracycline hydrochloride, gentamicin, ofloxacin, and chloramphenicol, the H2CBD has lower minimum inhibitory concentration and minimum bactericidal concentration for escherichia coli and staphylococcus aureus, and is a bacteriostatic agent with excellent performance.

In conclusion, the method is based on a novel efficient action mechanism, a high yield (90%) can be obtained by using less catalyst (1%) and mild catalyst (Lewis acid), the industrial cost is greatly reduced, and the method can be popularized to alkylation reaction of more reactants.

The above-mentioned embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. The equivalent substitution or change made by the technical personnel in the technical field on the basis of the invention is all within the protection scope of the invention. The protection scope of the invention is subject to the claims.

Claims

1. A method for synthesizing 8, 9-dihydrocannabidiol is characterized by comprising the following steps:

in an organic solvent, reacting alpha-phellandrene with olive alcohol under the action of a Lewis acid catalyst to obtain the 8, 9-dihydrocannabidiol; the Lewis acid catalyst is ferric trichloride; the dosage of the Lewis acid catalyst is 0.45-0.9 percent of the mass of the olive alcohol.

2. A method of synthesizing 8, 9-dihydrocannabidiol as claimed in claim 1, characterised in that the organic solvent includes one or more of toluene, xylene, ethyl acetate, 1, 2-dichloroethane and acetone.

3. A method of synthesizing 8, 9-dihydrocannabidiol as claimed in claim 1, characterized in that the amount of organic solvent added is 2.8-5.6L/kg based on the mass of olivetol.

4. A method of synthesizing 8, 9-dihydrocannabidiol as recited in claim 1 wherein the mole ratio of α -phellandrene to olivine is (1.0-1.25): 1.0.

5. A process for the synthesis of 8, 9-dihydrocannabidiol as claimed in claim 1, wherein the temperature of the reaction is 15-75 ℃; the reaction time is 0.1-1.0 h.