阅读说明：本技术 一种青蒿素类化合物合成关键中间体的制备方法 (Preparation method of key intermediate for synthesizing artemisinin compound ) 是由 丁小兵 稂琪伟 高爽 于 2019-09-20 设计创作，主要内容包括：本发明涉及有机化工技术领域,特别是一种青蒿素类化合物合成关键中间体二氢青蒿酸的不对称制备方法。应用于青蒿素类化合物合成时,操作简便,提高了收率和产物纯度,易于产业化应用。(The invention relates to the technical field of organic chemical industry, in particular to an asymmetric preparation method of dihydroartemisinic acid as a key intermediate for synthesizing artemisinin compounds. When the method is applied to the synthesis of artemisinin compounds, the operation is simple and convenient, the yield and the product purity are improved, and the industrial application is easy.)

1. A preparation method of a key intermediate for synthesizing artemisinin compounds is characterized in that in a proper solvent, under the action of the following catalysts, arteannuic acid undergoes an asymmetric catalytic hydrogenation reaction under certain hydrogen pressure and temperature to generate dihydroarteannuic acid:

wherein the catalyst is selected from:

Pd/C and Raney Ni;

tetrafluoroborate [ (R) -PCy2-WudaPhos ] rhodium (I), diacetate [ (R) -4, 4 ' -bis (diphenylphosphino) -2, 2 ' -dihydro-3, 3 ' -spirobis (benzofuran ] ] ruthenium (II)), diacetate [ (R) - (+) -2, 2 ' -bis (diphenylphosphino) -1, 1 ' -binaphthyl ] ruthenium (II), and diacetate [ (R) -5, 5 ' -bis [ bis (3, 5-xylyl) phosphino ] -4, 4 ' -bis-1, 3-benzodioxole ] ruthenium (II);

wherein Ar is Ph, p-Me-Ph, p-OMe-Ph, 3, 5-di-Me-Ph, 3, 5-di-tBu-Ph;

diacetate [ (R) -Binap ] ruthenium (II) diacetate [ (R) -C3-Tunephos ] ruthenium (II), diacetate [ (R) -Segphos ] ruthenium (II), diacetate [ (R) -biphen ] ruthenium (II), diacetate [ (R) -dtbm-Segphos ] ruthenium (II), diacetate [ (R) -Binap ] ruthenium (II); di-acetate [ (S) -C3-Tunephos ] ruthenium (II), di-acetate [ (S) -Segphos ] ruthenium (II), di-acetate [ (S) -Biphep ] ruthenium (II), di-acetate [ (S) -dtbm-Segphos ] ruthenium (II).

2. The method for preparing the key intermediate for synthesizing the artemisinin compound, according to claim 1, is characterized in that the solvent is one or more selected from water, methanol, ethanol, isopropanol, trifluoroethanol, nonanol, heptanol and dichloromethane.

3. The method for preparing the key intermediate for synthesizing the artemisinin compound according to claim 1 or 2, which is characterized by comprising the following steps:

wherein the catalyst is selected from Pd/C and Raney Ni, the molar ratio of palladium carbon to artemisinic acid is 0.01: 1-1: 1, and the molar ratio of Raney nickel to artemisinic acid is 0.01-1: 1.

4. The method for preparing the key intermediate for synthesizing the artemisinin compound according to claim 1 or 2, wherein the (R) -Binap ligand and the phenyl ruthenium dichloride (II) dimer are dissolved in N, N-dimethylformamide, heated overnight, cooled to room temperature, added with any one of sodium acetate, sodium tetrafluoroborate and sodium hexafluorophosphate, added with methanol until the dissolution is complete, and added with deionized water while stirring to obtain a gray yellow solid precipitate, wherein the catalyst is selected from (R) -Binap-Ru (OAc)₂The mol ratio of the anion selected from the catalyst to the arteannuic acid is 0.001: 1-0.01: 1, and the hydrogen pressure is 1-80 atm.

5. The method for preparing key intermediate of artemisinin compound according to claim 1 or 2, wherein Rh (NBD)₂BF₄，(R)-PCy₂-WudaPhos is dissolved in dichloromethane, stirred at normal temperature, and the solvent is pumped to obtain the catalyst precursor, and the further preparation method comprises the following steps:

wherein the molar ratio of the catalyst to the artemisinic acid is 0.0001: 1-0.01: 1, the hydrogen pressure is 1-80 atm, and the solvent is CF₃CH₂OH。

6. The method for preparing the key intermediate for synthesizing the artemisinin compound, according to the claim 1 or 2, is characterized in that (R) -O-SDP ligand and phenyl ruthenium dichloride (II) dimer are dissolved in N, N-dimethylformamide, heated overnight, cooled to room temperature, added with any one of sodium acetate, sodium tetrafluoroborate and sodium hexafluorophosphate, added with methanol until the dissolution is complete, and added with deionized water while stirring to obtain a gray yellow solid precipitate, and the method further comprises the following steps:

wherein the catalyst is selected from (R) -O-SDP, wherein the aryl group Ar is selected from Ph, p-Me-Ph, p-OMe-Ph, wherein S/C is 100.

7. The process for preparing key intermediates in the synthesis of artemisinin compounds according to claim 1 or 2, wherein (R) -Segphos ligand and phenyl ruthenium (II) dichloride dimer are dissolved in N, N-dimethylformamide, heated overnight, cooled to room temperature, any one of sodium acetate, sodium tetrafluoroborate and sodium hexafluorophosphate is added, methanol is added until complete dissolution is achieved, deionized water is added while stirring to obtain a gray yellow solid precipitate, and the process further comprises:

wherein the catalyst is selected from (R) -Segphos-Ru (OAc)₂The molar ratio of the catalyst to the artemisinic acid is 0.001: 1-0.01: 1, and the alkali is any one of lithium hydroxide, lithium carbonate, sodium hydroxide, anhydrous sodium carbonate, potassium hydroxide, anhydrous potassium carbonate, potassium tert-butoxide, sodium ethoxide, cesium carbonate, triethylamine and N, N-diisopropylethylamine.

8. The method for preparing the key intermediate for synthesizing the artemisinin compound according to the claim 1 or the claim 2, wherein the catalyst is prepared into diacetate, and the further preparation method comprises the following steps:

wherein the catalyst is selected from (R) -Binap, (R) -C3-Tunephos, (R) -Segphos, (R) -Biphep, (R) -dtbm-Segphos, (S) -Binap, (S) -C3-Tunephos, (S) -Segphos, (S) -Biphep, (S) -dtbm-Segphos, and the molar ratio of the catalyst to the artemisinic acid is 0.001: 1-0.01: 1.

9. The process for preparing key intermediates in the synthesis of artemisinin compounds according to claim 1 or 2, wherein (R) -Segphos ligand and phenyl ruthenium (II) dichloride dimer are dissolved in N, N-dimethylformamide, heated overnight, cooled to room temperature, added with sodium acetate, added with methanol until complete dissolution, and added with deionized water while stirring to obtain a yellow gray solid precipitate, further prepared by:

wherein the solvent alcohol is selected from one or more of methanol, ethanol, isopropanol, trifluoroethanol, nonanol, heptanol and dichloromethane, the alkali is selected from any one of lithium hydroxide, lithium carbonate, sodium hydroxide, anhydrous sodium carbonate, potassium hydroxide, anhydrous potassium carbonate, potassium tert-butoxide, sodium ethoxide, cesium carbonate, triethylamine and N, N-diisopropylethylamine, the temperature is 30-40 ℃, and H is H₂The pressure was 20-40bar, TON ═ 10,000.

10. A process for the preparation of artemisinin compounds, which comprises preparing an intermediate by a process as claimed in any one of claims 1 to 9 for the preparation of a key intermediate in the synthesis of artemisinin compounds.

Technical Field

The invention relates to the technical field of organic chemical industry, in particular to a preparation method of a key intermediate for synthesizing artemisinin compounds.

Background

The artemisinin and the derivatives can generate immune regulation and anti-inflammatory effects by inhibiting T cell activation and promoting T cell apoptosis, are first-line medicines for treating malaria, treat systemic lupus erythematosus and psoriasis entering a clinical stage, and have specific killing effect on various tumor cells.

Compared with artemisinin (content of 0.1-1% w/w) extracted from plant Artemisia annua, semi-preparation of artemisinin from artemisinic acid has the advantages of economy, environmental protection, high efficiency and stability. But also face locational-and chemo-selectivity difficulties.

The DHAA is used as a key intermediate for synthesizing the artemisinin compound, and is applied to the preparation of artemisinin and derivatives thereof through the following synthetic route.

However, due to chemo-selectivity problems, hydrogenation of non-target double bonds and the production of different configurational isomers as non-target products often result, reducing yield and purity.

Known synthetic routes to DHAA include:

philippe CHARERAU of Sonofield introduces the DHAA synthesis route adopted by Philippe CHARERAU at the ICES science conference as follows:

however, the yield and productivity of the compound are still to be further improved.

Moreover, zhangwan and the like have made intensive studies on the synthesis of DHAA, and specifically include the applied patents CN201210181561.7 and CN201410478803.8, etc., and mainly achieved through the following routes.

However, commercial use is limited based on the ease of availability of the ligand for particular uses. The main defects of the prior art are that the dosage of the catalyst is higher, and the diastereoselectivity still has a space for improving.

Disclosure of Invention

In view of the problems in the prior art, the invention provides a preparation method of a key intermediate for synthesizing artemisinin compounds.

The preparation method is characterized in that in a proper solvent, under the action of the following catalyst, artemisinic acid undergoes asymmetric catalytic hydrogenation reaction under certain hydrogen pressure and temperature to generate dihydroartemisinic acid:

wherein the catalyst is selected from:

Pd/C and Raney Ni;

tetrafluoroborate [ (R) -PCy2-WudaPhos ] rhodium (I), diacetate [ (R) -4, 4 ' -bis (diphenylphosphino) -2, 2 ' -dihydro-3, 3 ' -spirobis (benzofuran ] ] ruthenium (II)), diacetate [ (R) - (+) -2, 2 ' -bis (diphenylphosphino) -1, 1 ' -binaphthyl ] ruthenium (II), and diacetate [ (R) -5, 5 ' -bis [ bis (3, 5-xylyl) phosphino ] -4, 4 ' -bis-1, 3-benzodioxole ] ruthenium (II);

wherein Ar is Ph, p-Me-Ph, p-OMe-Ph, 3, 5-di-Me-Ph, 3, 5-di-tBu-Ph;

diacetate [ (R) -Binap ] ruthenium (II) diacetate [ (R) -C3-Tunephos ] ruthenium (II), diacetate [ (R) -Segphos ] ruthenium (II), diacetate [ (R) -biphen ] ruthenium (II), diacetate [ (R) -dtbm-Segphos ] ruthenium (II), diacetate [ (R) -Binap ] ruthenium (II); di-acetate [ (S) -C3-Tunephos ] ruthenium (II), di-acetate [ (S) -Segphos ] ruthenium (II), di-acetate [ (S) -Biphep ] ruthenium (II), di-acetate [ (S) -dtbm-Segphos ] ruthenium (II).

As a preferable technical scheme of the invention, the solvent is one or more selected from water, methanol, ethanol, isopropanol, trifluoroethanol, nonanol, heptanol and dichloromethane.

As a preferred embodiment of the present invention, the catalyst is preferably selected from:

as a preferred technical scheme of the invention, the preparation method comprises the following steps:

wherein the catalyst is selected from Pd/C and RaneyNi, the molar ratio of palladium carbon to artemisinic acid is 0.01: 1-1: 1, and the molar ratio of Raney nickel to artemisinic acid is 0.01-1: 1.

The catalyst is selected from Pd/C and Raney Ni, and S/C is 20-100.

More specifically, the preparation method comprises the following steps: 1.06mg Pd/C was added to 1ml methanol solvent, 234mg artemisinic acid was added, and the mixture was stirred at room temperature for 12 hours. Or adding 0.59mg of Raney nickel into 1ml of methanol solvent, adding 234mg of arteannuic acid, and stirring at room temperature for 12 h.

As a preferred technical scheme of the invention, the (R) -Binap ligand and phenyl ruthenium dichloride (II) dimer are dissolved in N, N-dimethylformamide, heated overnight, cooled to room temperature, any one of sodium acetate, sodium tetrafluoroborate and sodium hexafluorophosphate is added, methanol is added until the solution is completely dissolved, deionized water is added during stirring to obtain a gray yellow solid precipitate, wherein the catalyst is selected from (R) -Binap-Ru (OAc)₂Anions ofThe mol ratio of the selected catalyst to the arteannuic acid is 0.001: 1-0.01: 1, and the hydrogen pressure is 1-80 atm.

More specifically, the preparation method comprises the following steps:

6.2mg of (R) -Binap ligand and 2.5mg of phenylruthenium (II) dichloride dimer were dissolved in 5ml of N, N-dimethylformamide and heated at 110 ℃ overnight. Cooling to room temperature, adding any one of sodium acetate, sodium tetrafluoroborate and sodium hexafluorophosphate, and adding methanol until the mixture is completely dissolved. Adding 1ml of deionized water while stirring to obtain 8.0mg of gray yellow solid precipitate;

under argon atmosphere, 0.1mmol of artemisinic acid, 1ml of trifluoroethanol and 0.085mg of chiral catalyst were added. The autoclave was purged with hydrogen to 20 atm, the pressure was reduced to 5 atm, and the pressure was raised to 50atm after repeating five times. The mixture was stirred at 60 ℃ for 4 hours and the solvent was removed under reduced pressure.

Wherein the catalyst is selected from (R) -Binap-Ru (OAc)₂And (R) -Segphos-Ru (OAc)₂，S/C＝1000。

As a preferable embodiment of the present invention, Rh (NBD)₂BF₄，(R)-PCy₂-WudaPhos is dissolved in dichloromethane, stirred at normal temperature, and the solvent is pumped to obtain a catalyst precursor;

more specifically, 0.037mg Rh (NBD)₂BF₄Red crystals, 0.063mg of (R) -PCy₂-WudaPhos yellow crystals were dissolved in 0.5ml of dichloromethane, stirred at room temperature for 45min, and the solvent was drained to obtain a catalyst precursor.

The preparation method comprises the following steps:

wherein the molar ratio of the catalyst to the artemisinic acid is 0.0001: 1-0.01: 1, the hydrogen pressure is 1-80 atm, and the solvent is CF₃CH₂OH。

More specifically, the preparation method comprises the following steps: under argon atmosphere, 0.1mmol of artemisinic acid, 1ml of trifluoroethanol and 0.086mg of chiral catalyst were added. The autoclave was purged with hydrogen to 20 atm, the pressure was reduced to 5 atm, and the pressure was raised to 50atm after repeating five times. Stirring at 60 deg.C for 8h, and removing solvent under reduced pressure.

Wherein the solvent is CF₃CH₂OH。

As a preferred technical scheme of the invention, the (R) -O-SDP ligand and the phenyl ruthenium dichloride (II) dimer are dissolved in N, N-dimethylformamide, heated overnight, cooled to room temperature, added with any one of sodium acetate, sodium tetrafluoroborate and sodium hexafluorophosphate, added with methanol until the mixture is completely dissolved, and added with deionized water while stirring to obtain a gray yellow solid precipitate.

More specifically, 6.2mg of (R) -O-SDP ligand and 2.5mg of phenylruthenium (II) dichloride dimer were dissolved in 5ml of N, N-dimethylformamide and heated at 110 ℃ overnight. Cooling to room temperature, adding any one of sodium acetate, sodium tetrafluoroborate and sodium hexafluorophosphate, and adding methanol until the mixture is completely dissolved. 1ml of deionized water was added with stirring to give 8.0mg of a pale yellow solid precipitate.

The preparation method comprises the following steps:

wherein the catalyst is selected from (R) -O-SDP, wherein the aryl group Ar is selected from Ph, p-Me-Ph, p-OMe-Ph, wherein S/C is 100.

More specifically, the preparation method comprises the steps of adding 0.1mmol of arteannuic acid, 1ml of trifluoroethanol, 16mg of cesium carbonate and 0.080mg of chiral catalyst under the argon atmosphere. The autoclave was purged with hydrogen to 20 atm, the pressure was reduced to 5 atm, and the pressure was raised to 40 atm after repeating five times. The mixture was stirred at 40 ℃ for 4h and the solvent was removed under reduced pressure.

Wherein the catalyst is selected fromWherein aryl is Ph, p-Me-Ph, (p-OMe-Ph, S/C ═ 100.

As a preferred technical scheme of the invention, the (R) -Segphos ligand and the phenyl ruthenium dichloride (II) dimer are dissolved in N, N-dimethylformamide, heated overnight, cooled to room temperature, added with any one of sodium acetate, sodium tetrafluoroborate and sodium hexafluorophosphate, added with methanol until the methanol is completely dissolved, and added with deionized water while stirring to obtain a gray yellow solid precipitate.

More specifically, 6.1mg of (R) -Segphos ligand and 2.5mg of phenylruthenium (II) dichloride dimer were dissolved in 5ml of N, N-dimethylformamide and heated at 110 ℃ overnight. Cooling to room temperature, adding any one of sodium acetate, sodium tetrafluoroborate and sodium hexafluorophosphate, and adding methanol until the mixture is completely dissolved. 1ml of deionized water was added with stirring to give 8.1mg of a pale yellow solid precipitate.

The preparation method comprises the following steps:

wherein the catalyst is selected from (R) -Segphos-Ru (OAc)₂The molar ratio of the catalyst to the artemisinic acid is 0.001: 1-0.01: 1, and the alkali is any one of lithium hydroxide, lithium carbonate, sodium hydroxide, anhydrous sodium carbonate, potassium hydroxide, anhydrous potassium carbonate, potassium tert-butoxide, sodium ethoxide, cesium carbonate, triethylamine and N, N-diisopropylethylamine.

As a preferred technical scheme of the invention, the catalyst is prepared into diacetate salt, and the preparation method comprises the following steps:

wherein the catalyst is selected from (R) -Binap, (R) -C3-Tunephos, (R) -Segphos, (R) -Biphep, (R) -dtbm-Segphos, (S) -Binap, (S) -C3-Tunephos, (S) -Segphos, (S) -Biphep, (S) -dtbm-Segphos, and the molar ratio of the catalyst to the artemisinic acid is 0.001: 1-0.01: 1.

More specifically, the preparation method comprises the following steps:

wherein the catalyst is selected from (R) -Binap-Ru (OAc)₂S/C1000, the base being selected from C_S2CO₃And NaHCO₃。

As a preferred technical scheme of the invention, the (R) -Segphos ligand and the phenyl ruthenium dichloride (II) dimer are dissolved in N, N-dimethylformamide, heated overnight, cooled to room temperature, added with sodium acetate and methanol until the solution is completely dissolved, and added with deionized water while stirring to obtain a gray yellow solid precipitate.

More specifically, 11.8mg of (R) -Segphos ligand and 2.5mg of phenylruthenium (II) dichloride dimer were dissolved in 5ml of N, N-dimethylformamide and heated at 110 ℃ overnight. Cooled to room temperature, 1.2mg of sodium acetate was added, and methanol was added until complete dissolution. 1ml of deionized water was added with stirring to give 11.2mg of a pale yellow solid precipitate.

The preparation method comprises the following steps:

wherein the solvent alcohol is selected from one or more of methanol, ethanol, isopropanol, trifluoroethanol, nonanol, heptanol, and dichloromethane, and the alkali is selected from lithium hydroxide, lithium carbonate, sodium hydroxide, anhydrous sodium carbonate, potassium hydroxide, anhydrous potassium carbonate, potassium tert-butoxide, sodium ethoxide, and carbonAny one of cesium acid, triethylamine and N, N-diisopropylethylamine at the temperature of 30-40 ℃ and H₂The pressure was 20-40bar, TON ═ 10,000.

More specifically, the preparation method comprises the following steps:

wherein the catalyst is selected from (R) -Binap, (R) -C3-Tunephos, (R) -Segphos, (R) -Biphep, (R) -dtbm-Segphos.

More specifically, the preparation method comprises the following steps:

wherein the solvent is selected from MeOH and NaHCO₃At a volume concentration of 5% and a temperature of 30-40 deg.C, H₂The pressure was 20-40bar, TON ═ 10,000.

The invention further provides a preparation method of the artemisinin compound, which is used for preparing the intermediate by adopting the preparation method for synthesizing the key intermediate by the artemisinin compound. The intermediate is used for preparing artemisinin compounds, and the synthetic route is as follows

The beneficial effects of the invention compared with the prior art comprise:

the invention provides a preparation method of a key intermediate for synthesizing artemisinin compounds. When the method is applied to the synthesis of artemisinin compounds, the yield and the product purity are improved, and the method is easy for industrial application.

Drawings

FIG. 1 is a schematic diagram of a synthetic route for preparing artemisinin from an artemisinin compound synthesis key intermediate.

FIG. 2 is a schematic diagram of LC-MS detection of DHAA, a key intermediate for synthesizing artemisinin compounds.

FIG. 3 shows that the artemisinin compound of the present invention synthesizes key intermediate DHAA¹H NMR (CDCl₃) Detection schematic.

FIG. 4 is a schematic diagram of HPLC detection of a key intermediate DHAA synthesized from artemisinin compounds.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the embodiments of the invention are not limited thereto.

Example 1

TABLE 1 reaction with Pd/C and Raney Ni

^aThe yield and de values were determined by reverse phase HPLC analysis.^bNR ═ unreacted NA ═ not obtained, under raney nickel catalysis, the preferred conditions give > 99% conversion and 65% de.

Example 2

Table 2: asymmetric hydrogenation of ligands using R and S configuration

^aThe yield and de values were determined by reverse phase HPLC analysis.

The detection results of the intermediate DHAA are shown in fig. 2, 3 and 4, respectively. In the presence of catalyst (R) -Segphos-Ru (OAc)₂Conditions, preferably conditions, result in 95% conversion and 85.6% de.

Example 3

Table 3 DHAA was obtained by asymmetric hydrogenation of AA in different solvents and ligands.^a

^aThe reaction was carried out at a substrate/catalyst ratio of 5000/1, 60 deg.C, 50atm hydrogen pressure for 8h, 0.1mmol of artemisinic acid, 1.0ml of solvent.^bThe conversion was determined by 1H-NMR spectroscopy.^cThe yield and de values were determined by reverse phase HPLC analysis.

In the presence of catalyst (R) -O-SDP-Ru (OAc)₂Under conditions, preferably conditions to achieve 98% conversion and 98% de.

Example 4

TABLE 4O-SDP ligand screening of different substituents

^aThe reaction was carried out on a 0.1mmol scale.^bThe conversion was determined by 1H-NMR spectroscopy.^cThe yield and de values were determined by reverse phase HPLC analysis.^dWith(S)-d the opposite configuration is obtained.

In the presence of catalyst (R) -O-SDP (p-OMe-Ph) -Ru (OAc)₂Under preferred conditions > 99% conversion and 99% de are obtained.

Example 5

TABLE 5 alkali, temperature and pressure screens

^aThe reaction was carried out on a 0.1mmol scale.^bThe conversion was determined by 1H-NMR spectroscopy.^cThe yield and de values were determined by reverse phase HPLC analysis.^dThe main product is DHAA.

In the presence of catalyst (R) -Binap-Ru (OAc)₂Conditions are preferred to obtain > 99% yield and 85% de.

Example 6

TABLE 6 screening of various commercial ligands

^aThe reaction was carried out on a 0.1mmol scale.^bBy passing¹The H-NMR spectrum determines the conversion.^cThe yield and de values were determined by reverse phase HPLC analysis.^dRecrystallization from EtOH/HCl.

In the presence of catalyst (R) -dtbm-Segphos-Ru (OAc)₂Under the condition, the conversion rate of more than 99 percent and 93 percent de are obtained under the optimized condition, and the 99 percent de can be obtained through one-time recrystallization.

Example 7

TABLE 7 different alcohol solvent screens (TON ═ 10,000)

^aThe reaction was carried out on a 0.1mmol scale.^bBy passing¹The H-NMR spectrum determines the conversion.^cThe yield and de values were determined by reverse phase HPLC analysis.^dRecrystallization from EtOH/HCl.^eSelective NaHCO₃Relative to Ca₂CO₃Has more economical efficiency.

In the presence of catalyst (R) -dtbm-Segphos-Ru (OAc)₂Under conditions, preferably conditions are obtained with > 99% conversion and 85% de.

Example 8

Table 8 screening of the amount of base used (TON ═ 10,000)

^aThis should be done on a 0.1mmol scale.^bBy passing¹The H-NMR spectrum determines the conversion.^cThe yield and de values were determined by reverse phase HPLC analysis.^dFinal solvent removal was determined.^eNR ═ unreacted and NA ═ not obtained.

In the presence of catalyst (R) -dtbm-Segphos-Ru (OAc)₂Under conditions, preferably conditions are obtained with > 99% conversion and 93% de.

Example 9

Referring to the schematic synthetic route shown in FIG. 1, the intermediate DHAA synthesized in examples 1-9 was used for the synthesis of artemisinin compounds.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.