阅读说明：本技术 制备阿塞那平的方法 (Process for the preparation of asenapine ) 是由 郑志国 于 2019-08-13 设计创作，主要内容包括：本发明涉及制备阿塞那平的方法。具体而言,本发明涉及制备可药用的阿塞那平游离碱以及其晶型的方法,还涉及该方法中所用的中间体化合物的制备方法。(The present invention relates to a process for the preparation of asenapine. In particular, the invention relates to a process for the preparation of pharmaceutically acceptable asenapine free base and crystalline forms thereof, and to a process for the preparation of intermediate compounds used in the process.)

1. A crystal of asenapine of formula I,

the method is characterized in that when powder X-ray diffraction analysis is carried out under CuK alpha ray experimental conditions, diffraction signal peaks exist at 2 theta angle positions of 9.0 +/-0.2 degrees, 11.2 +/-0.2 degrees, 18.0 +/-0.2 degrees, 22.1 +/-0.2 degrees, 22.4 +/-0.2 degrees and 22.6 +/-0.2 degrees.

2. A crystal of asenapine of formula I according to claim 1, characterized in that it has diffraction signal peaks at angular positions 2 Θ of 9.0 ± 0.2 °, 10.9 ± 0.2 °, 11.2 ± 0.2 °, 18.0 ± 0.2 °, 19.4 ± 0.2 °, 19.7 ± 0.2 °, 21.5 ± 0.2, 22.1 ± 0.2 °, 22.4 ± 0.2 °, 22.6 ± 0.2 °, 25.3 ± 0.2 ° when analyzed by powder X-ray diffraction using CuK α ray experimental conditions.

3. A process for the preparation of the crystalline form of asenapine of formula I which comprises dissolving a crude asenapine in the recrystallization solvent of claim 5, cooling, stirring for crystallization, and vacuum drying to give the crystalline form compound of formula I.

4. The method for preparing asenapine crystal form of formula I according to claim 3, wherein hexane, n-hexane or n-heptane, or a mixed solvent thereof with toluene, xylene, ethyl acetate, isopropyl ether, tetrahydrofuran or methyltetrahydrofuran is added to the crude asenapine, and after heating, stirring and dissolving, the temperature is reduced to separate out a solid, and the product is collected by filtration and dried in vacuum to obtain the crystal form compound of formula I.

5. The process for preparing asenapine crystal form of formula I according to claim 3, wherein acetone, methanol, ethanol, propanol or isopropanol is added to the crude asenapine product, after heating to dissolve it, water is then added, and cooling crystallization is performed, or a mixed solvent of acetone, methanol, ethanol, propanol or isopropanol and water is added, after heating to dissolve it, cooling crystallization is performed, the product is collected by filtration, and vacuum drying is performed to obtain the crystalline form compound of formula I.

6. A process for the preparation of asenapine crystalline form of formula I according to claim 3 wherein the acid salt of asenapine is dissolved in water or an organic solvent, neutralized with an equivalent amount of a base, concentrated to dryness by extraction with an aprotic solvent and then prepared according to the process of claim 4 or 5.

7. The method of claim 6, wherein the organic solvent is selected from methanol, ethanol, isopropanol, N-methylpyrrolidone, DMF, DMSO, acetonitrile, tetrahydrofuran, or methyltetrahydrofuran; the acid salt of asenapine is selected from hydrochloride, hydrobromide, hydroiodide, maleate, fumarate or tartrate.

Technical Field

The present invention relates to the field of synthesis of organic compounds. In particular, the invention relates to a preparation method of an antipsychotic drug Asenapine (Asenapine), namely a compound trans-5-chloro-2-methyl-2, 3,3a,12 b-tetrahydro-1H-dibenzo [2,3:6,7] -oxepino [4,5-c ] pyrrole and a novel crystal form thereof.

Background

Asenapine (Asenapine), a compound trans-5-chloro-2-methyl-2, 3,3a,12 b-tetrahydro-1H-dibenzo [2,3:6,7] -oxepino [4,5-c ] pyrrole, the maleate salt of which is useful in the emergency treatment of adult schizophrenia, mania or mixed episodes with type I bipolar disorder. The action mechanism of asenapine may be related to the antagonism of dopamine D2 and 5-hydroxytryptamine 2A, and is suitable for treating mania or mixed type attack of schizophrenia and bipolar I disorder, and has good antipsychotic effect. Antipsychotics have now become the 5 th treatment category behind cholesterol lowering medications, with sales reaching $ 162 billion in the global market. In China, the antipsychotic drug market keeps more than 40% of the compound growth rate every year, and the market share of the anti-schizophrenia drugs is about 30% and is growing at a rate of 9.8% every year. Therefore, research and development of a new preparation method of asenapine suitable for industrial production are necessary.

At present, a plurality of documents and patents are reported about the synthesis of asenapine. Initially, U.S. Pat. No. 4,45434 and the literature (Vader, J.; Kasperssen, F.; Sperling, E.; Schlactiter, I.; Terpsra, A.; Hilberink, P.; Wagenaars, G.J. Labelled composite. radiopharm.1994,34,845) 869, respectively, reported the preparation of asenapine, the synthetic route of which is as follows:

the main problems of the synthetic route are that the obtained asenapine is a mixture of cis-trans isomers, the separation operation of the isomers is very complicated, and the yield is low, so that the method is difficult to be used for industrial production.

The 2008 document (org. process res. dev.,2008,12(2), 196-201) reports the improvement of the above synthesis process, which is as follows:

the method is characterized in that strong base is utilized to hydrolyze and open loop lactam, isomerization reaction is carried out simultaneously, then the loop is closed to obtain a needed trans lactam intermediate, and finally lithium aluminum hydride is used for reduction to obtain asenapine. Through the improvement, the problem of separation and purification of the product is solved, and the total yield is improved. However, this synthetic route is lengthy, and the starting material 2- (5-chloro-2-phenoxy) phenylacetic acid still needs to be synthesized by the following method. In addition, the multi-step reaction of the above method uses a reagent which is highly polluting to the environment and a dangerous reagent such as lithium aluminum hydride, etc., and thus is not favorable for industrial production.

Afterwards, the 2008 patent US2008009619 reports that ortho-bromobenzyl bromide is used as a raw material to react with triethyl phosphite to obtain benzyl phosphonate, then the benzyl phosphonate reacts with salicylaldehyde through Horner-Wadsworth-Emmons to obtain a trans-tetrahydropyrrole intermediate, and finally a target compound is obtained through intramolecular ullmann reaction.

The method has short synthetic route and obtains single isomer. However, when preparing benzyl phosphonate ester, a strong irritant raw material of o-bromobenzyl bromide is needed, and a long-time high-temperature reaction is needed. In addition, the yield of the last walking-step ullmann reaction is low, and the reaction needs to be carried out for a long time at high temperature in the presence of cesium carbonate, cuprous halide and N, N-dimethylglycine, so that the problems of environmental pollution and high production cost exist.

Similar to the above synthesis method, in 2011 CN102229613 reports a new synthesis process of asenapine:

the method takes 2-bromo-beta-nitrostyrene and 2-methoxy-5-chlorophenylacetic acid methyl ester as initial raw materials, obtains cis-trans isomeric mixture through condensation, reduction, cyclization and methylation reaction, and obtains the target product asenapine through de-etherification, intramolecular Ullmann cyclization and reduction. Although the synthesis method can isomerize cis-trans isomeric mixture into single trans compound, the operation is simplified and the yield is improved. However, the n-butyllithium used in the process needs to be controlled below-60 ℃, and LiAlH is used for lactam reduction₄And is inflammable and explosive, so that the reaction in industrial production is limited.

Recently, in 2015 CN104974168 reported a preparation method of asenapine and a method for preparing asenapineIntermediates of serapine. The method uses 2-chloro-5-nitrobenzaldehyde and o-methoxybenzyl acetonitrile as starting materials, obtains a trans-form single isomer through condensation, addition and cyclization reactions, and obtains a target product asenapine through substitution, reduction, de-etherification, cyclization and diazotization reactions. However, the synthesis method needs to use highly toxic cyanide and flammable and explosive reagent LiAlH₄. The reaction operation has risks in industrial production.

In conclusion, the synthesis method of asenapine reported at present generally has the defects of complex process operation, great environmental pollution, use of flammable and explosive reagents, long synthesis route and the like. Therefore, there is a need for further research on a simple and efficient synthesis method suitable for industrialization of asenapine.

In order to overcome the defects of the above route, the invention provides a novel synthetic method of asenapine. The method has the characteristics of convenient operation, high product yield, good purity of the intermediate and the target product and the like, and is easy for industrial production.

Disclosure of Invention

In the present invention, the following terms have the meanings as described below:

“C_5-9alkane "means a branched or linear alkane having 5 to 9 carbon atoms, such as pentane, n-pentane, hexane, n-hexane or n-heptane.

“C_1-6Alkyl "and" C_1-4Alkyl "denotes branched or straight-chain alkyl groups having 1 to 6 and 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, respectively.

"halogen" or "halo" or "halogen atom" means fluorine, chlorine, bromine or iodine.

The "Huisgen cycloaddition reaction" is a cycloaddition reaction between a 1, 3-dipole and an alkene, alkyne or corresponding derivative, the product being a five-membered heterocyclic compound. Olefinic compounds are known as dipolar donors in reactions. The German chemist Rolf Huisgen first of all uses this type of reaction extensively to prepare five-membered heterocyclic compounds, and is therefore also referred to as the Huisgen reaction.

"diazo deamination" refers to a process in which a diazotization reaction of an amino group and a reaction in which the diazo group is substituted with a hydrogen atom are combined to remove the amino group, and is called diazo deamination. Namely, the amino is firstly subjected to diazotization reaction to obtain a diazo compound, and then the diazo compound is reacted with a reduction reagent to obtain the reaction of the deamination compound with the diazo substituted by hydrogen atoms.

The invention aims to provide a novel preparation method of asenapine and obtain a novel crystal form of asenapine free base.

In a first aspect, the present invention provides a process for the preparation of asenapine of formula I:

the method comprises the following steps:

(a-1) carrying out intramolecular nucleophilic substitution reaction on the intermediate II under an alkaline condition to obtain a cyclic ether intermediate III,

wherein X is F, Cl, Br or I,

wherein the base is an alkali metal hydroxide, an alkali metal carbonate, an alkali metal bicarbonate, a metal hydride, a metal organic compound or a non-nucleophilic organic strong base,

(a-2) reducing the nitro group in the intermediate III to obtain an intermediate IV,

and (a-3) carrying out diazotization deamination reaction on the intermediate IV, and then recrystallizing and purifying to obtain the pure asenapine product shown in the formula I.

In the step (a-1): and carrying out intramolecular nucleophilic substitution reaction on the intermediate II and phenolic hydroxyl on another benzene ring under the conditions of alkaline, aprotic solvent and mild reaction to obtain a cyclic ether intermediate III.

The base used in this step can be selected from alkali metal hydroxides LiOH, NaOH, KOH, RbOH, CsOH, FrOH, alkali metal carbonates Li₂CO₃、Na₂CO₃、K₂CO₃、Rb₂CO₃、Cs₂CO₃Alkali metal bicarbonate NaHCO₃、KHCO₃Metal organic compounds butyl lithium, methyl magnesium chloride, tert-butyl magnesium chloride, ethyl magnesium bromide, butyl magnesium bromide, metal hydrides NaH, KH, CaH₂The strong non-nucleophilic organic base LDA, LiHMDS or NaHMDS.

The solvent for the reaction is an aprotic solvent, for example selected from toluene, xylene, tetrahydrofuran, methyltetrahydrofuran, diethyl ether, isopropyl ether, methyl tert-butyl ether, dioxane, acetonitrile, sulfolane, N-methylpyrrolidone, DMF, DMSO, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, or a mixture of two or more thereof.

The reaction temperature is 0-100 ℃, preferably 20-70 ℃.

After the reaction is finished, cooling to room temperature, adding drinking water to separate out a product, filtering, and drying in vacuum to constant weight to obtain a cyclic ether intermediate III.

In the step (a-2): and (3) carrying out catalytic hydrogenation reduction on the nitro in the intermediate III to obtain an intermediate IV.

The solvent used in this step is C_1-4Alcohol solvents such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, tert-butanol, water, or a mixture of two or more thereof.

The reaction temperature is 30-70 ℃.

In the reaction, nitro is reduced into amino by catalytic hydrogenation, and the adopted reducing agent can be selected from Pd/C, Ni, iron, zinc and sodium sulfide.

In the step (a-3): and carrying out diazotization deamination reaction on the intermediate IV, and recrystallizing and purifying to obtain the asenapine pure product shown in the formula I.

And dissolving the intermediate IV in a reduction reagent for diazotization deamination reaction, dropwise adding the diazotization reagent at the temperature of-5-30 ℃, reacting by a one-pot method, adjusting the pH value to be neutral by using alkali, separating out a solid, and filtering to obtain a crude product. And then recrystallized to give asenapine in crystalline form.

The diazotizing agent employed in the reaction is a nitrite salt, such as sodium nitrite or potassium nitrite.

The reducing agent for diazotization deamination reaction used in the reaction can be selected from methanol, ethanol, isopropanol, hypophosphorous acid, borohydride (including sodium borohydride and potassium borohydride) or nitrite.

The nitrite is selected from methyl nitrite, ethyl nitrite, tert-butyl nitrite, n-amyl nitrite or isoamyl nitrite.

The base used in this step may be selected from sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonia, aqueous methylamine solution or triethylamine.

The solvent used for recrystallization purification can be selected from C_5-9An alkane (e.g., n-pentane, hexane, n-hexane, or n-heptane, or a mixture of two or more thereof), an aromatic hydrocarbon solvent (e.g., benzene, toluene, xylene, chlorobenzene, or a mixture of two or more thereof), an ester solvent (e.g., ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, tert-butyl acetate, or a mixture of two or more thereof), a ketone solvent (e.g., acetone, methyl ethyl ketone, or a mixture thereof), an ether solvent (e.g., diethyl ether, isopropyl ether, methyl tert-ether, tetrahydrofuran, methyl tetrahydrofuran, or a mixture of two or more thereof), an alcohol solvent (e.g., methanol, ethanol, propanol, isopropanol, or a mixture of two or more thereof), water, or a mixture of two or more thereof), a solvent (e.g., methanol, ethanol, propanol, isopropanol, or aThe solvent is a mixture of two or more solvents, preferably n-heptane or a mixture thereof with other solvents.

In a second aspect, a process for preparing asenapine of formula I, comprising the steps of:

wherein the intermediate IV is subjected to diazotization deamination reaction and then recrystallization purification to obtain asenapine of the formula I.

Dissolving the intermediate IV in a reducing reagent used for diazotization deamination reaction, dropwise adding the diazotization reagent at the temperature of-5-30 ℃, reacting by a one-pot method, adjusting the pH value to be neutral by alkali, separating out solid, and filtering to obtain a crude product. And then recrystallized to give asenapine in crystalline form.

The diazotization reagent adopted by the reaction is sodium nitrite or potassium nitrite.

The reducing agent used in the reaction may be selected from methanol, ethanol, isopropanol, hypophosphorous acid, borohydride (including sodium borohydride and potassium borohydride) or nitrite.

The nitrite is selected from methyl nitrite, ethyl nitrite, tert-butyl nitrite, n-amyl nitrite or isoamyl nitrite.

In a third aspect, the invention provides crystals of asenapine of formula I, and a process for the preparation of the crystals.

The invention provides asenapine represented by formula I in the form of a crystal characterized in that, when powder X-ray diffraction analysis is performed using CuK alpha ray experimental conditions, the characteristic diffraction positions are represented by 2 theta angles of 9.0 + -0.2 degrees, 11.2 + -0.2 degrees, 18.0 + -0.2 degrees, 22.1 + -0.2 degrees, 22.4 + -0.2 degrees, 22.6 + -0.2 degrees.

More specifically, in the powder X-ray diffraction pattern of the asenapine crystal of the formula I, the characteristic diffraction positions have 2 theta angles of 9.0 + -0.2 DEG, 10.9 + -0.2 DEG, 11.2 + -0.2 DEG, 18.0 + -0.2 DEG, 19.4 + -0.2 DEG, 19.7 + -0.2 DEG, 21.5 + -0.2 DEG, 22.1 + -0.2 DEG, 22.4 + -0.2 DEG, 22.6 + -0.2 DEG, 25.3 + -0.2 deg.

The crystal PXRD spectrum of asenapine in formula I is shown in figure 1, the infrared spectrum is shown in figure 2, and the DSC spectrum is shown in figure 3.

The preparation and purification method of the invention is adopted to obtain a crystal form of asenapine of formula I, which is characterized in that when powder X-ray diffraction analysis is carried out under CuK alpha ray experimental conditions, the diffraction position is 2 theta angle value (DEG) or d valueThe diffraction peak relative intensity peak Height (Height%) or peak Area (Area%) is shown in the following table:

a process for preparing a crystalline form of asenapine of formula I comprising: dissolving the asenapine crude product in a recrystallization solvent, stirring at room temperature for crystallization, filtering, and drying in vacuum to obtain the asenapine free base with the crystal form.

The solvent used for recrystallization purification can be selected from C_1-9An alkane (e.g., n-pentane, hexane, n-hexane, or n-heptane, or a mixture of two or more thereof), an aromatic hydrocarbon solvent (e.g., benzene, toluene, xylene, chlorobenzene, or a mixture of two or more thereof), an ester solvent (e.g., ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, tert-butyl acetate, or a mixture of two or more thereof), a ketone solvent (e.g., acetone, methyl ethyl ketone, or a mixture thereof), an ether solvent (e.g., diethyl ether, isopropyl ether, methyl tert-ether, tetrahydrofuran, methyl tetrahydrofuran, or a mixture of two or more thereof), an alcohol solvent (e.g., methanol, ethanol, propanol, isopropanol, or a mixture of two or more thereof), water, or a mixed solvent of two or more of the above solvents, preferably n-heptaneOr a mixed solvent thereof with other solvents.

In one embodiment, a process for preparing a crystalline form of asenapine of formula I comprises: adding a recrystallization solvent, such as hexane, n-hexane or n-heptane, or a mixed solvent of the recrystallization solvent and toluene, xylene, ethyl acetate, isopropyl ether, tetrahydrofuran or methyltetrahydrofuran, into the asenapine crude product, heating, stirring, dissolving, cooling to separate out a solid, filtering, collecting a product, and drying in vacuum to obtain the crystal form compound of the formula I.

The dissolving temperature is 30-70 ℃, preferably 35-50 ℃.

And (3) carrying out heat preservation crystallization at the crystallization temperature of 15-25 ℃ for 1.0-1.5 h, cooling to-20-0 ℃, preferably to-20-10 ℃ at the speed of 5-10 ℃ per hour, stirring for 1.0-1.5 h under the heat preservation condition, filtering, washing with a proper amount of hexane, n-hexane or n-heptane, filtering, and carrying out vacuum drying at the temperature of 30-60 ℃ to obtain the crystal form compound of the formula I.

In another embodiment, a process for preparing a crystalline form of asenapine of formula I comprises: adding a recrystallization solvent such as acetone, methanol, ethanol, propanol or isopropanol into the asenapine crude product, heating for dissolving, then adding water, cooling for crystallizing, or adding a mixed solvent of acetone, methanol, ethanol, propanol or isopropanol and water, heating for dissolving, cooling for crystallizing, filtering and collecting a product, and vacuum-drying to obtain the crystal form compound of the formula I.

The dissolving temperature is 30-70 ℃, preferably 35-50 ℃.

And (3) carrying out heat preservation crystallization at the temperature of 20-25 ℃ for 1.0-1.5 h at the crystallization temperature of 20-25 ℃, cooling to-5-15 ℃, preferably to-5 ℃ at the speed of 5-10 ℃ per hour, stirring for 1.0-1.5 h at the heat preservation temperature, filtering, washing with a proper amount of crystallization solvent, filtering, and carrying out vacuum drying at the temperature of 30-60 ℃ to obtain the crystal form compound of the formula I.

The process for preparing asenapine crystals of formula I may further comprise: dissolving asenapine acid salt with water or organic solvent, neutralizing with equivalent amount of alkali, extracting with aprotic solvent, concentrating to dry, and recrystallizing.

The organic solvent used for dissolving can be selected from methanol, ethanol, isopropanol, N-methyl pyrrolidone, DMF, DMSO, acetonitrile, tetrahydrofuran or methyl tetrahydrofuran.

The acidic salt of asenapine may be selected from the group consisting of hydrochloride, hydrobromide, hydroiodide, maleate, fumarate or tartrate.

The base may be selected from sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, cesium carbonate, lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium tert-butoxide or potassium tert-butoxide.

The aprotic organic solvent can be selected from hexane, n-heptane, toluene, xylene, isopropyl ether, methyl tert-butyl ether, or a mixture of two or more thereof.

The obtained asenapine of the formula I can also be salified with acid to prepare a pharmaceutically acceptable salt thereof, and the preparation method comprises the steps of reacting asenapine with hydrochloric acid to prepare asenapine hydrochloride, and reacting asenapine with maleic acid to prepare asenapine maleate.

In a fourth aspect, the present invention provides a compound of formula II, having the structure:

wherein X is F, Cl, Br or I.

Specifically, the compound of formula II includes the following four compounds:

furthermore, the present invention provides a process for the preparation of a compound of formula II, comprising the steps of:

in the step (b-1): under the action of sulfuric acid and halogen acid, hydroxyl in the structure of 2-halogen-5-nitrobenzol (V) is substituted by halogen atom, and then the 2-halogen-5-nitrobenzol (V) and triethyl phosphite react in an aprotic organic solvent under the catalysis of Lewis acid to obtain an intermediate VI.

The hydrohalic acid used in this step includes hydrofluoric acid, hydrochloric acid, hydrobromic acid or hydroiodic acid. The Lewis acid being FeCl₂、FeCl₃、FeBr₃、ZnCl₂、ZnBr₂Or InBr₂。

The aprotic organic solvent may be selected from dichloromethane, chloroform, tetrahydrofuran, methyltetrahydrofuran, benzene, toluene, xylene, chlorobenzene, etc., or a mixed solvent of two or more thereof.

Specifically, a compound V (2-halogen-5-nitrobenzol), halogen acid and sulfuric acid are mixed according to the weight ratio of 1.0: 1.2-3.0: 0.2-1.0 equivalent, heated to 20-55 ℃, kept warm and stirred for reaction for 5-14 hours, then extracted by an aprotic solvent, washed by drinking water and weak base, and dried by a drying agent to remove water, so as to obtain an intermediate solution. And then adding catalyst Lewis acid and triethyl phosphite, heating the reaction solution to 30-50 ℃, stirring and reacting for 6-12 h, slightly cooling after the reaction is finished, adding drinking water for washing, separating, and concentrating the organic layer under reduced pressure until the organic layer is dried to obtain the compound in the formula VI, wherein the next step of reaction is directly carried out without purification.

The weight ratio of the compound V, the halogen acid and the sulfuric acid is preferably 1.0: 1.5-2.0: 0.5-0.8. The reaction time is preferably 8-12 h.

The weak base is selected from one or more of sodium carbonate, potassium carbonate, cesium carbonate, sodium bicarbonate or potassium bicarbonate. The drying agent is anhydrous magnesium sulfate or anhydrous sodium sulfate.

In the step (b-2): and (3) reacting the intermediate VI with 5-chlorosalicylaldehyde VII under an alkaline condition to obtain an intermediate VIII through Horner-Wadsworth-Emmons reaction.

The molar ratio of the intermediate VI to the 5-chlorosalicylaldehyde in the step is that the intermediate VI to the 5-chlorosalicylaldehyde is 1.0: 1.2.

The base is selected from lithium hydroxide, sodium hydroxide, potassium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium tert-butoxide, sodium tert-butoxide, or a mixture of two or more thereof.

The reaction solvent is aprotic solvent, and can be selected from benzene, toluene, xylene, chlorobenzene, tetrahydrofuran, methyltetrahydrofuran, isopropyl ether, methyl tert-butyl ether, or mixture of two or more thereof.

The reaction temperature is-5 to 25 ℃, preferably-5 to 10 ℃.

In the step (b-3): and (4) acetylating the intermediate VIII and acetic anhydride under an alkaline condition to obtain an intermediate IX.

In this step, the molar ratio of the intermediate VIII to acetic anhydride is 1.0:1.8, preferably 1.2: 1.5.

The base employed may be selected from organic bases such as diethylamine, triethylamine, isopropylamine, pyridine or p-dimethylaminopyridine, or inorganic bases such as sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, cesium carbonate, sodium hydride or potassium hydride.

The reaction solvent may be selected from benzene, toluene, xylene, chlorobenzene, tetrahydrofuran, methyltetrahydrofuran, isopropyl ether, methyl tert-butyl ether, or a mixed solvent of two or more thereof.

The reaction temperature is 5-55 ℃.

Water, methanol, ethanol or isopropanol can be added for the post-treatment to separate out the compound IX.

In the step (b-4): the intermediate IX is subjected to a Huisgen cycloaddition reaction with N- (alkoxymethyl) -N-methyl- (trimethylsilyl) methylamine in an aprotic solvent at ambient temperature under the catalysis of trifluoroacetic acid, and then deprotection is carried out under alkaline conditions to obtain an intermediate II.

Wherein R in the compound of formula X is C_1-6Alkyl, R is preferably-CH₃and-Bu-n.

The molar ratio of intermediate ix to compound of formula X is intermediate ix to compound X is 1.0:1.5, preferably 1.1: 1.3.

The reaction solvent in the step can be one or a mixture of two or more of benzene, toluene, xylene, chlorobenzene, tetrahydrofuran, methyltetrahydrofuran, isopropyl ether and methyl tert-butyl ether.

The solvent used for deacetylation is C_1-4An alcoholic solvent selected from methanol, ethanol, propanol, isopropanol or butanol. The alkali is alkali metal aqueous solution, and can be selected from lithium hydroxide, sodium hydroxide, and potassium hydroxide aqueous solution.

In a fifth aspect, the present invention provides another process for preparing a compound of formula II:

wherein X is F, Cl, Br or I.

In the step (c-1): under the action of sulfuric acid and halogen acid, hydroxyl in the structure of the compound (V) is replaced by halogen atoms, and then the compound is reacted with triphenylphosphine in an aprotic organic solvent to obtain an intermediate XI.

The hydrohalic acid used in this step includes hydrofluoric acid, hydrochloric acid, hydrobromic acid or hydroiodic acid of various concentrations.

The aprotic organic solvent used may be selected from dichloromethane, chloroform, tetrahydrofuran, methyltetrahydrofuran, benzene, toluene, xylene, chlorobenzene, or a mixed solvent of two or more thereof.

Specifically, a compound V (2-halogen-5-nitrobenzol), halogen acid and sulfuric acid are mixed according to the weight ratio of 1.0: 1.0-3.0: 0.2-1.0 equivalent, heated to 20-85 ℃, kept warm and stirred for reaction for 5-14 hours, then extracted by an aprotic solvent, washed by drinking water and weak alkali, and dried by a drying agent to remove water, so as to obtain an intermediate solution. And then adding triphenylphosphine, heating the reaction solution to 30-70 ℃, stirring for reaction for 6-12 h, cooling to room temperature after the reaction is finished, and filtering to obtain the compound shown in the formula XI.

The weight ratio of the compound V to the halogen acid to the sulfuric acid is preferably 1.0: 1.2-1.5: 0.2-0.5. The reaction time is preferably 8-12 h.

The weak base is one or more of sodium carbonate, potassium carbonate, cesium carbonate, sodium bicarbonate or potassium bicarbonate. The drying agent is anhydrous magnesium sulfate or anhydrous sodium sulfate.

In the step (c-2): and carrying out Witting reaction on the intermediate XI and 5-chlorosalicylaldehyde VII under an alkaline condition to obtain an intermediate VIII.

The base used in this step may be selected from inorganic bases such as lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium tert-butoxide, potassium tert-butoxide, or organic bases such as triethylamine, pyridine, p-dimethylaminopyridine, diisopropylethylamine.

The molar ratio of the intermediate XI to 5-chlorosalicylaldehyde in the step is 1: 1.05-1.5, preferably 1: 1.05-1.3.

The reaction temperature is 20-80 ℃, and preferably 40-70 ℃.

The reaction solvent is an aprotic organic solvent, and can be selected from dichloromethane, chloroform, tetrahydrofuran, methyltetrahydrofuran, benzene, toluene, xylene, chlorobenzene, or a mixed solvent of two or more of the above.

In the step (b-3): and (4) acetylating the intermediate VIII and acetic anhydride under an alkaline condition to obtain an intermediate IX.

In this step, the molar ratio of the intermediate VIII to acetic anhydride is 1.0:1.8, preferably 1.2: 1.5.

The base employed may be selected from organic bases such as diethylamine, triethylamine, isopropylamine, pyridine or p-dimethylaminopyridine, or inorganic bases such as sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, cesium carbonate, sodium hydride or potassium hydride.

The reaction solvent can be one or a mixture of two or more of benzene, toluene, xylene, chlorobenzene, tetrahydrofuran, methyltetrahydrofuran, isopropyl ether and methyl tert-butyl ether.

The reaction temperature is 5-55 ℃.

Water, methanol, ethanol or isopropanol can be added for the post-treatment to separate out the compound IX.

In the step (b-4): the intermediate IX is subjected to a Huisgen cycloaddition reaction with N- (alkoxymethyl) -N-methyl- (trimethylsilyl) methylamine in an aprotic solvent at ambient temperature under the catalysis of trifluoroacetic acid, and then deprotection is carried out under alkaline conditions to obtain an intermediate II.

Wherein R in the compound of formula X may be C_1-6Alkyl, R is preferably-CH₃and-Bu-n.

The molar ratio of intermediate ix to compound of formula X is intermediate ix to compound X is 1.0:1.5, preferably 1.1: 1.3.

The reaction solvent in the step can be one or a mixture of two or more of benzene, toluene, xylene, chlorobenzene, tetrahydrofuran, methyltetrahydrofuran, isopropyl ether and methyl tert-butyl ether.

The solvent used for deacetylation is C_1-4Alcohol solvent selected from methanol, ethanol, propanol, isopropanol, and butanol. The alkali is alkali metal aqueous solution, and can be selected from lithium hydroxide, sodium hydroxide, and potassium hydroxide aqueous solution.

The core points of the invention are as follows: the 2-halogen-5-nitrobenzyl halide and triethyl phosphite are catalyzed by Lewis acid to obtain an intermediate IV under mild reaction conditions, so that the high-temperature long-time reaction of 2-bromine-benzyl bromide used for preparing phosphonate ester in the prior art (US2008009619) is avoided. By utilizing the strong electron-withdrawing effect of halogen atoms of a pyrrolidine benzene ring in the intermediate II on a para-nitro group, the dibenzo [2,3:6,7] oxepino [4,5-c ] pyrrole ring is constructed by intramolecular nucleophilic substitution reaction with phenolic hydroxyl on another benzene ring under mild alkaline conditions, and the defect that the dibenzo [2,3:6,7] oxepino [4,5-c ] pyrrole ring of asenapine constructed by the prior art (US2008009619) needs to be subjected to long-time high-temperature intramolecular Ullmann reaction is overcome. And the crystallization method and the obtained crystal can simplify the post-treatment, improve the purification efficiency and reduce the cost, thereby being very beneficial to the industrialized mass production.

Compared with the prior art, the method for preparing asenapine avoids the use of inflammable and explosive hazardous reducing agents LiAlH in the prior art (US4145434, org. Process Res. Dev.,2008,12(2), 196-containing 201, CN102229613, CN104974168)₄And the separation and purification process of isomers is also avoided, and the process is simplified. Meanwhile, the invention does not need high-temperature long-time reaction operation (US2008009619), and avoidsThe dangerous and toxic reagents of butyl lithium and methyl iodide (CN102229613) are avoided, and methyl iodide, boron tribromide and hydrazine hydrate (CN104974168) are not used. The method has the advantages of mild reaction conditions, simple operation, little environmental pollution, low cost and the like, thereby being more suitable for industrial production.

Drawings

Fig. 1 is a PXRD pattern of asenapine crystals of the present invention. Fig. 2 is an infrared spectrum of an asenapine crystal of the present invention. Figure 3 is a DSC profile of asenapine crystals of the present invention.

Detailed Description

The process of the present invention is further illustrated by the following examples. It should be understood that the following examples are provided only for the purpose of enabling a better understanding of the present invention, and are not intended to limit the scope of the present invention in any way.

The first embodiment is as follows:

step (b-1): synthesis of Compound VI:

adding 35.2g of compound V and 63.3g of 48% hydrobromic acid aqueous solution into a 200ml reaction bottle, dropwise adding 18.4g of sulfuric acid at room temperature, heating to 50 ℃, keeping the temperature for 10 hours, cooling to room temperature, adding 100ml of dichloromethane, washing the organic layer by using 50ml of water and 50ml of sodium carbonate aqueous solution, adding 10g of sodium sulfate for drying, filtering, adding 63.1g of triethyl phosphite and 8.6g of anhydrous zinc bromide into the organic layer at one time, heating the reaction solution to 40 ℃, stirring the reaction mixture for 10 hours, slightly cooling, adding 100ml of water for washing, separating a water layer, collecting an organic phase, and evaporating the solvent under reduced pressure to obtain a compound VI (54.8g, 95.0%).

Step (b-2): synthesis of Compound VIII

Under the protection of nitrogen, 54.0g of compound VI is dissolved in 500ml of tetrahydrofuran, 30.1g of 5-chlorosalicylaldehyde is added, the mixture is cooled to 0 ℃, 39.2g of potassium tert-butoxide are added in portions while keeping the temperature at 0 ℃, 300ml of water and 300ml of toluene are added after the reaction is completed, the organic layer is washed with 200ml of sodium carbonate solution and saturated sodium chloride solution, and the organic layer is evaporated to dryness under reduced pressure at 50 ℃ to obtain compound VIII (52.9g, 97.2%)

Step (b-3): synthesis of Compound IX

Adding 52.0g of compound VIII, 17.1g of pyridine and 200ml of toluene under the protection of nitrogen, dropwise adding 21.7g of acetic anhydride at room temperature, reacting overnight, heating to 50 ℃, adding 41ml of water and 13ml of ethanol, keeping the temperature for 30min, cooling to room temperature, and filtering to obtain a product IX (58.2g, 98.5%)

¹H NMR(400MHz,CDCl₃)δ(ppm):8.48(d,1H),8.07-8.10(dd,1H),8.67-8.68(d,1H),7.57–7.60(d,1H),7.44–7.48(d,1H),7.31-7.34(dd,1H),7.14-7.18(d,1H),7.08-7.10(d,1H),2.41(s,3H).

Step (b-4): synthesis of Compound II

58.0g of compound IX are dissolved in 500ml of toluene, 0.5g of trifluoroacetic acid are added, 32.7g N- (methoxymethyl) -N-methyl- (trimethylsilyl) methylamine is added dropwise within 1 hour, the mixture is incubated at ambient temperature for 3 hours, and the organic layer is concentrated in vacuo to give an oil. The oil was dissolved in 400ml of methanol and aqueous potassium hydroxide (10.5 g of potassium hydroxide in 90ml of water) was added. After 1h the pH was adjusted to 8-9 with 3N hydrochloric acid, the mixture was stirred for 30min and filtered and the product was dried under vacuum for 10h to give compound II (56.0g, 92.6%)

¹H NMR(400MHz,CDCl₃)δ(ppm):12.39(s,-OH),8.26(s,1H),8.04-8.06(d,1H),7.52–7.54(d,1H),7.05–7.06(d,1H),6.81-6.83(d,1H),6.76(s,1H),4.13(s,1H),3.67-3.70(t,1H),3.31(s,1H),3.24-3.26(d,1H),2.95-2.98(t,1H),2.57(s,3H),2.37-2.41(t,1H).

¹³C NMR(101MHz,CDCl₃)δ(ppm):154.75,147.05,142.12,141.12,131.30,131.13,129.44,128.45,123.34,123.02,122.79,119.43,63.23,61.66,51.42,48.24,39.95.

Step (a-1): synthesis of Compound III

Under nitrogen protection, 50.0g of compound II and 250ml of tetrahydrofuran were added to a reaction flask, stirred, then 22.6g of potassium carbonate was added, the reaction was incubated for 3h at 50-60 ℃ and cooled to ambient temperature, 750ml of water was added dropwise, the mixture was stirred for 30min and filtered, and the product was dried under vacuum to give compound III (43.1g, 95.6%).

¹H NMR(400MHz,CDCl₃)δ(ppm):8.07-8.10(dd,1H),7.98-7.99(d,1H),7.26–7.29(d,1H),7.18–7.21(m,1H),7.13–7.15(d,2H),3.66-3.73(m,1H),3.52–3.60(m,1H),3.30-3.35(m,1H),3.13-3.23(m,3H),2.57(s,3H).

¹³C NMR(101MHz,CDCl₃)δ(ppm):159.71,153.14,143.59,133.89,132.45,130.12,127.88,126.27,123.58,122.39,121.91,59.66,58.35,45.74,44.39,42.97.

MS(ESI):m/z＝330.08,[M+H]⁺＝331.08.

Step (a-2): synthesis of Compound IV

Dissolving 42.0g of compound III in 500ml of methanol, adding 4.0g of active nickel wet product, carrying out vacuum replacement, heating to 60 ℃, introducing hydrogen for reaction for 6-8 h, filtering to remove nickel, concentrating the reaction solution under vacuum to obtain oily matter, dissolving the oily matter in 250ml of methanol, adding 250ml of water under stirring, stirring the mixture for 30min and filtering. The product was dried under vacuum to give compound IV (36.4g, 95.4%).

Step (a-3): synthesis of compound I asenapine

Dissolving 36.0g of compound IV in 117g of hypophosphorous acid, cooling to 10-20 ℃, dropwise adding 31.2g of 30% sodium nitrite aqueous solution, and finishing dropwise adding for 3-4 h. And after finishing dripping, controlling the temperature to be 10-20 ℃, preserving the temperature and stirring for 6-8 hours. And (3) dropwise adding 78.0g of ammonia water at the temperature of below 30 ℃, adjusting the pH of a water layer to 8-9, adding 156ml of n-heptane, washing an organic layer with 78ml of water, and evaporating the organic layer at 50 ℃ under reduced pressure to dryness to obtain a crude product.

Adding 110ml of n-heptane and 8.0ml of toluene into the crude product, heating to 40-50 ℃, stirring for dissolving, cooling at a speed of 5-10 ℃ per hour for crystallization, cooling to 20-25 ℃, stirring for crystallization for 1.0-1.5 h, cooling to-5-0 ℃ after a large amount of solids are separated out, stirring for 1.0h under heat preservation, filtering, collecting the crystallized asenapine, and drying at 40-45 ℃ in vacuum to obtain a crystal form compound (30.6g, 89.5%, HPLC purity is more than 99%).

¹H NMR(400MHz,CDCl₃)δ(ppm):7.14-7.20(m,2H),7.11(s,2H),7.05–7.09(m,3H),3.58–3.68(m,2H),3.18–3.25(m,2H),3.08-3.16(m,2H),2.55(s,3H).

¹³C NMR(101MHz,CDCl₃)δ(ppm):155.22,151.14,134.01,131.88,128.91,127.64,127.33,126.79,126.71,124.15,122.35,120.90,59.12,59.00,44.83,44.72,43.25.

MS(ESI):m/z＝285.09,[M+H]⁺＝286.10.

Example two:

dissolving 73.0g of the compound IV in 220g of hypophosphorous acid, cooling to 0-15 ℃, dropwise adding 64.0g of 30% sodium nitrite aqueous solution, and finishing dropwise adding for 2-3 h. And after finishing dripping, controlling the temperature to be 10-20 ℃, preserving the temperature and stirring for 5-9 hours. And (3) dropwise adding 160g of ammonia water at the temperature controlled below 30 ℃, adjusting the pH of the water layer to be 8-9, adding 300ml of n-hexane, washing the organic layer with 160ml of water, and evaporating the organic layer at 45-50 ℃ under reduced pressure to dryness to obtain a crude product.

Adding 230ml of n-heptane and 17ml of toluene into the crude product, heating to 40-50 ℃, stirring for dissolving, cooling at a speed of 5-10 ℃ per hour for crystallization, cooling to 20-25 ℃, stirring for crystallization for 1.0-1.5 h, cooling to-5-0 ℃ after a large amount of solids are separated out, keeping the temperature and stirring for 1.0h, filtering, collecting the crystallized asenapine, and drying at 40-45 ℃ in vacuum to obtain a crystal form compound (63.3g, 91.2%, HPLC purity is more than 99%).

Example three:

step (c-1): synthesis of Compound XI

A250 ml reaction flask was charged with 50.0g of Compound V and 75.0g of a 48% aqueous solution of hydrobromic acid, 14.0g of sulfuric acid was added dropwise at room temperature, the mixture was warmed to 60 ℃ and kept warm for 13 hours, cooled to room temperature, 100ml of toluene was added, the organic layer was washed with 35.0g of water and 28.0g of a 2.5% aqueous solution of sodium carbonate in this order, and the mixture was allowed to stand for separation, 65.2g of triphenylphosphine was added to the organic layer, stirred at 60 ℃ for 10 hours, then cooled to ambient temperature, and filtered to obtain Compound XI (118.8g, 95.2%).

Step (c-2): synthesis of Compound VIII

102.4g of the compound XI are dissolved in 1000ml of tetrahydrofuran under nitrogen protection, 37.4g of 5-chlorosalicylaldehyde are added, 15.8g of pyridine is added dropwise, after the reaction is completed, 600ml of water and 600ml of hexane are added, the organic layer is washed with 400ml of sodium carbonate solution and saturated sodium chloride solution, the organic layer is evaporated to dryness under reduced pressure at 50 ℃, and the compound VIII (62.8g, 92.6%) is obtained by column chromatography.

Step (b-3): synthesis of Compound IX

Adding 60.0g of compound VIII, 21.5g of triethylamine and 230ml of tetrahydrofuran under the protection of nitrogen, dropwise adding 33.4g of acetic anhydride at the temperature of 15-30 ℃, reacting overnight, heating to 45 ℃, adding 46ml of water and 15ml of ethanol, keeping the temperature for 30min, cooling to room temperature, and filtering to obtain a product IX (66.8g, 98.0%)

Step (b-4): synthesis of Compound II

65.0g of compound IX are dissolved in 540ml of tetrahydrofuran, 1.0g of trifluoroacetic acid are added, 37.0g of 37.0g N- (methoxymethyl) -N-methyl- (trimethylsilyl) methylamine is added dropwise within 1 hour, the mixture is incubated at ambient temperature for 3 hours, and the organic layer is concentrated in vacuo to give an oil. The oil was dissolved in 435ml of ethanol and aqueous potassium hydroxide (13.7 g of potassium hydroxide in 117ml of water) was added. After 1h the pH was adjusted to 8-9 with 3N hydrochloric acid, the mixture was stirred for 30min and filtered and the product was dried under vacuum for 11h to give compound II (62.4g, 92.0%)

Example four: preparation method of asenapine crystal of formula I

Adding 180ml of n-heptane and 15ml of toluene into 60.0g of asenapine crude product, heating to 35-45 ℃, stirring, dissolving, cooling at a speed of 5-10 ℃ per hour, crystallizing, cooling to 15-25 ℃, stirring at a constant temperature for 1.0h, cooling to-20-10 ℃, stirring at a constant temperature for 1.0h, filtering, collecting the crystallized asenapine, and drying at 35-45 ℃ under vacuum to obtain the asenapine crystal compound (55.2g, 92.0%, HPLC purity is more than 99%) of the formula I.

Example five: process for preparing the crystals of asenapine of formula I

Adding 300g of ethanol into 95.0g of asenapine crude product, heating to 40-50 ℃ to completely dissolve the raw material, controlling the temperature to be 30-40 ℃, dropwise adding 45g of purified water, cooling to 20-25 ℃, and carrying out heat preservation and crystallization for 1.0-1.5 h. And slowly cooling to 0-5 ℃, keeping the temperature and stirring for 1h, filtering, leaching with a proper amount of ethanol water solution, filtering to obtain a wet product, and vacuum-drying at 50-60 ℃ to obtain the crystalline compound (91.4g, 96.2% and HPLC purity of more than 99%) of asenapine in the formula I.

Example six: process for preparing crystalline asenapine of formula I

To a 3.0% aqueous solution of 400g of sodium hydroxide, 400g of hexane was added at room temperature, then 84.0g of asenapine maleate was added in portions, and after dissolving by stirring, the layers were separated, the aqueous layer was extracted with 150g of hexane, and the organic layers were combined. The organic layer was washed with 2X 150g of water and the organic layer was concentrated to dryness under reduced pressure. Adding 200g of hexane and 20g of ethyl acetate into a reaction system, heating to 45-55 ℃, stirring, dissolving, cooling to 15-25 ℃, carrying out heat preservation and crystallization for 1.5h, then cooling to-15-10 ℃, filtering, collecting a product, and carrying out vacuum drying at 35-45 ℃ to obtain a crystalline compound (69.3g, 93.1%, HPLC purity is more than 99%) of asenapine in the formula I.

The implementation scheme is as follows:

1. a method for preparing Asenapine (Asenapine) with a formula I,

characterized in that the method comprises the following steps:

(a-1) subjecting the intermediate II to intramolecular nucleophilic substitution reaction under alkaline condition to obtain a cyclic ether intermediate III,

wherein X is F, Cl, Br or I,

wherein the base is an alkali metal hydroxide, an alkali metal carbonate, an alkali metal bicarbonate, a metal hydride, a metal organic compound or a non-nucleophilic organic strong base,

(a-2) reducing the nitro group in the intermediate III to obtain an intermediate IV,

(a-3) carrying out diazotization deamination reaction on the intermediate IV, then recrystallizing and purifying to obtain the pure asenapine product shown in the formula I,

2. the process of embodiment 1 for the preparation of asenapine of formula I wherein the base used in step (a-1) is selected from the group consisting of LiOH, NaOH, KOH, RbOH, CsOH, FrOH, Li₂CO₃、Na₂CO₃、K₂CO₃、Rb₂CO₃、Cs₂CO₃、LiHCO₃、NaHCO₃、KHCO₃、NaH、KH、CaH₂Butyl lithium, methyl magnesium chloride, tert-butyl magnesium chloride, ethyl magnesium bromide, butyl magnesium bromide, LDA, LiHMDS or NaHMDS.

3. The process for the preparation of asenapine of formula i according to any of embodiments 1-2, wherein the solvent reacted in step (a-1) is an aprotic solvent, for example selected from toluene, xylene, tetrahydrofuran, methyltetrahydrofuran, diethyl ether, isopropyl ether, methyl tert-butyl ether, dioxane, acetonitrile, sulfolane, N-methylpyrrolidone, DMF, DMSO, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, or a mixture of two or more thereof.

4. The process for preparing asenapine of formula I according to any of embodiments 1 to 3, wherein the reducing agent used in the diazotization deamination reaction in step (a-3) is methanol, ethanol, isopropanol, hypophosphorous acid, sodium borohydride, potassium borohydride or nitrite.

5. The process for preparing asenapine of formula I according to any of embodiments 1 to 4, wherein in the step (a-3), the solvent used for the recrystallization purification is selected from C_5-9An alkane (e.g., n-pentane, hexane, n-hexane or n-heptane, or a mixture of two or more thereof), an aromatic hydrocarbon solvent (e.g., benzene, toluene, xylene, chlorobenzene, or a mixture of two or more thereof), an ester solvent (e.g., ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, tert-butyl acetate, or a mixture of two or more thereof), a ketone solvent (e.g., acetone, methyl ethyl ketone, or a mixture thereof), an ether solvent (e.g., diethyl ether, isopropyl ether, methyl tert-ether, tetrahydrofuran, methyl tetrahydrofuran, or a mixture of two or more thereof), an alcohol solvent (e.g., methanol, ethanol, propanol, isopropanol, or a mixture of two or more thereof), water, or a mixed solvent of two or more of the above solvents, n-heptane or a mixed solvent thereof with other solvents is preferable.

6. A process for preparing asenapine of formula I comprising the steps of:

wherein the intermediate IV is subjected to diazotization deamination reaction and then recrystallization purification to obtain asenapine of formula I

7. The preparation process according to embodiment 6: the method is characterized in that a reducing reagent used in the diazotization deamination reaction in the step is methanol, ethanol, isopropanol, hypophosphorous acid, sodium borohydride or nitrite.

8. A crystal of asenapine of formula I,

the method is characterized in that when powder X-ray diffraction analysis is carried out under CuK alpha ray experimental conditions, diffraction signal peaks exist at 2 theta angle positions of 9.0 +/-0.2 degrees, 11.2 +/-0.2 degrees, 18.0 +/-0.2 degrees, 22.1 +/-0.2 degrees, 22.4 +/-0.2 degrees and 22.6 +/-0.2 degrees.

9. A crystal of asenapine of formula I according to embodiment 8, characterized by having diffraction signal peaks at angular positions 2 θ of 9.0 ± 0.2 °, 10.9 ± 0.2 °, 11.2 ± 0.2 °, 18.0 ± 0.2 °, 19.4 ± 0.2 °, 19.7 ± 0.2 °, 21.5 ± 0.2, 22.1 ± 0.2 °, 22.4 ± 0.2 °, 22.6 ± 0.2 °, 25.3 ± 0.2 °, when subjected to powder X-ray diffraction analysis using CuK α ray experimental conditions.

10. A preparation method of asenapine crystal form of formula I comprises the steps of dissolving asenapine crude product in a recrystallization solvent described in embodiment 5, cooling, stirring, crystallizing, and vacuum drying to obtain the crystal form compound of formula I.

11. The method for preparing asenapine crystal form of formula I according to embodiment 10, wherein hexane, n-hexane, or n-heptane, or a mixed solvent thereof with toluene, xylene, ethyl acetate, isopropyl ether, tetrahydrofuran, or methyltetrahydrofuran is added to the crude asenapine, and after heating, stirring and dissolving, the temperature is reduced to precipitate a solid, and the product is collected by filtration and vacuum-dried to obtain the crystal form compound of formula I.

12. The method for preparing asenapine crystal form of formula I according to embodiment 10, wherein acetone, methanol, ethanol, propanol or isopropanol is added to the crude asenapine, after heating to dissolve it, water is then added, and cooling crystallization is performed, or a mixed solvent of acetone, methanol, ethanol, propanol or isopropanol and water is added, after heating to dissolve it, cooling crystallization is performed, the product is collected by filtration, and vacuum drying is performed to obtain the crystalline form compound of formula I.

13. A process for the preparation of the crystalline form of asenapine of formula I according to embodiment 10, wherein the acid salt of asenapine is dissolved with water or an organic solvent, neutralized with an equivalent amount of a base, extracted with an aprotic solvent and concentrated to dryness, and then prepared according to the process of embodiment 11 or 12.

14. The method of embodiment 13, wherein the organic solvent is selected from methanol, ethanol, isopropanol, N-methylpyrrolidone, DMF, DMSO, acetonitrile, tetrahydrofuran, or methyltetrahydrofuran; the acid salt of asenapine is selected from hydrochloride, hydrobromide, hydroiodide, maleate, fumarate or tartrate.

15. A compound of formula II:

wherein X is F, Cl, Br or I.

16. A process for the preparation of a compound of formula ii comprising the steps of:

wherein X is F, Cl, Br or I,

step (b-1): under the action of sulfuric acid and halogen acid, hydroxyl in the structure of the compound (V) is substituted by halogen atom, and then the compound reacts with triethyl phosphite in an aprotic organic solvent under the catalysis of Lewis acid to obtain an intermediate VI,

step (b-2): the intermediate VI and 5-chloro salicylaldehyde VII are reacted under the alkaline condition to obtain an intermediate VIII,

step (b-3): the intermediate VIII and acetic anhydride are acetylated under the alkaline condition to obtain an intermediate IX,

step (b-4): intermediate IX is subjected to Huisgen cycloaddition reaction with N- (alkoxymethyl) -N-methyl- (trimethylsilyl) methylamine (X) under the catalysis of trifluoroacetic acid to obtain intermediate II, wherein R is C_1-6An alkyl group.

17. The production method according to embodiment 16, wherein the hydrohalic acid used in the step (b-1) is selected from the group consisting of hydrofluoric acid, hydrochloric acid, hydrobromic acid and hydroiodic acid; the Lewis acid being FeCl₂、FeCl₃、FeBr₃、ZnCl₂、ZnBr₂Or InBr₂(ii) a The aprotic organic solvent is selected from dichloromethane, chloroform, tetrahydrofuran, methyltetrahydrofuran, benzene, toluene, and dioxaneToluene, chlorobenzene, or a mixed solvent of two or more of them.

18. The production method according to any one of embodiments 16 to 17, characterized in that the base used in step (b-2) is selected from lithium hydroxide, sodium hydroxide, potassium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium tert-butoxide, or sodium tert-butoxide.

19. The preparation process according to any one of embodiments 16 to 18, wherein R in the compound of the formula X in step (b-4) is C_1-4Alkyl, preferably methyl or n-butyl.

20. A process for the preparation of a compound of formula II comprising the steps of:

wherein X is F, Cl, Br or I,

step (c-1): under the action of sulfuric acid and halogen acid, hydroxyl in the compound (V) is replaced by halogen atom, and then the compound is reacted with triphenylphosphine in an aprotic organic solvent to obtain an intermediate XI,

step (c-2): the intermediate XI and 5-chloro salicylaldehyde VII are subjected to Witting reaction under the alkaline condition to obtain an intermediate VIII,

step (b-3): the intermediate VIII and acetic anhydride are acetylated under the alkaline condition to obtain an intermediate IX,

step (b-4): intermediate IX is subjected to Huisgen cycloaddition reaction with N- (alkoxymethyl) -N-methyl- (trimethylsilyl) methylamine (X) under the catalysis of trifluoroacetic acid to obtain intermediate II, wherein R is C_1-6Alkyl, preferably methyl or n-butyl.

21. The process according to embodiment 20, wherein the hydrohalic acid used in the step (c-1) is selected from the group consisting of hydrofluoric acid, hydrochloric acid, hydrobromic acid and hydroiodic acid. The aprotic organic solvent is selected from dichloromethane, chloroform, tetrahydrofuran, methyl tetrahydrofuran, benzene, toluene, xylene, chlorobenzene, or a mixed solvent of two or more of them.

22. The production process according to any one of embodiments 20 to 21, wherein the base used in step (c-2) is selected from inorganic bases such as lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium tert-butoxide or potassium tert-butoxide, or organic bases such as triethylamine, pyridine, p-dimethylaminopyridine or diisopropylethylamine.