Novel method for synthesis of (S)-propisochlor

A technology of metolachlor and a new method, applied in the new field of synthesizing (S)-metolachlor, achieving the effects of high e.e. value, mild reaction, and overcoming racemization

Active Publication Date: 2009-02-18
NANJING UNIV OF TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, its main synthesis methods include enzymatic resolution of racemates[2,3], asymmetric catalytic hydrogenation reduction[4], among which asymmetric catalytic hydrogenation reduction is

Method used

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  • Novel method for synthesis of (S)-propisochlor

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] In a 250 ml three-necked flask equipped with a stirrer and a thermometer, 125 ml of toluene was added, and then 21 grams (0.11 moles) of p-toluenesulfonyl chloride and 10.4 grams (0.1 moles) of (D)-methyl lactate were dropped into the reaction flask 15.2 g (0.15 mol) of triethylamine was added dropwise, the temperature was controlled in an ice-water bath at -10°C to -5°C, and the reaction was tracked until the reaction of (D)-methyl lactate was complete. Filtrate, wash the filtrate with 45 ml of water, separate layers, extract the aqueous layer with 45 ml of dichloromethane, combine the organic layers, dry with 20 g of anhydrous sodium sulfate, filter, and spin the solvent to obtain a light yellow crude product. Then recrystallized with ether:n-hexane=1:1 to obtain 22 g of colorless crystal (R)-2-(p-toluenesulfonyloxy)methyl propionate, with a yield of 85% and an e.e. value of 97.1%. 14.1 grams (0.104 moles) of 2-methyl-6-ethylaniline are dropped into 100 milliliters of...

Embodiment 2

[0019]In a 250 ml three-necked flask equipped with a stirrer and a thermometer, 125 ml of methylene chloride was added, and then 21 grams (0.11 moles) of p-toluenesulfonyl chloride and 10.4 grams (0.1 moles) of (D)-methyl lactate were dropped into 12.1 g (0.12 mol) of triethylamine was added dropwise into the reaction flask, the temperature was controlled in an ice-water bath at -10°C to -5°C, and the reaction was tracked until the reaction of (D)-methyl lactate was complete. Filtrate, wash the filtrate with 45 ml of water, separate layers, extract the aqueous layer with 45 ml of dichloromethane, combine the organic layers, dry with 20 g of anhydrous sodium sulfate, filter, and spin the solvent to obtain a light yellow crude product. Then recrystallized with ether:n-hexane=1:1 to obtain 21.7 g of colorless crystal (R)-2-(p-toluenesulfonyloxy)methyl propionate, with a yield of 84% and an e.e. value of 98%. 11.9 grams (0.088 moles) of 2-methyl-6-ethylaniline were dropped into a ...

Embodiment 3

[0024] In a 250 ml three-necked flask equipped with a stirrer and a thermometer, 125 ml of 1,2-dichloroethane was added, and then 15.3 grams (0.08 moles) of p-toluenesulfonyl chloride and 10.4 grams (D)-methyl lactate ( 0.1 mol) into the reaction flask, drop 12.1 g (0.12 mol) of triethylamine, and control the temperature in an ice-water bath at -10°C to -5°C. The sulfonyl chloride reacts completely. Filtrate, wash the filtrate with 45 ml of water, separate layers, extract the aqueous layer with 45 ml of dichloromethane, combine the organic layers, dry with 20 g of anhydrous sodium sulfate, filter, and spin the solvent to obtain a light yellow crude product. Then recrystallized with ether:n-hexane=1:1 to obtain 17 g of colorless crystal (R)-2-(p-toluenesulfonyloxy)methyl propionate, with a yield of 82% and an e.e. value of 94%. Put 7.2 grams (0.053 moles) of 2-methyl-6-ethylaniline in a 100 ml three-necked flask equipped with a stirrer and a thermometer, and (R)-2-(p-toluenesu...

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Abstract

The present invention relates to a novel method of synthesizing (S)-metolachlor, and discloses a complete synthesis route which adopts chiron. In the novel method, (D)-methyl lactate or (D)-ethyl lactate is used as a raw material and reacts with p-toluenesulfonyl chloride to generate (R)-2-(p-tolylsulfonyl oxyl) propionate; the (R)-2-(p-tolylsulfonyl oxyl) propionate reacts with 2-methyl-6-ethyl aniline to prepare S-(-)-N-(2-methyl-6-ethyl benzyl) alanine ester; the S-(-)-N-(2-methyl-6-ethyl benzyl) alanine ester reacts with a reducing agent C to prepare S-(-)-N- (1'-methyl-2'-ethylol)-2-methyl-6-ethyl aniline; and the S-(-)-N- (1'-methyl-2'-ethylol)-2-methyl-6-ethyl aniline is acylated with chloroacetic chloride and ultimately methylated to prepare the (S)-metolachlor. The present invention has the advantages that no resolution is required in the whole process, the reaction is mild, the yield rate is high, the optical purity is good, the reaction time is short, the raw materials are inexpensive and can be easily acquired, and the cost is low.

Description

technical field [0001] The invention belongs to the research field of asymmetric synthesis in organic chemistry, and relates to a new method for synthesizing chiral pesticide (S)-metolachlor. technical background [0002] In 1952, Monsanto Company of the United States discovered that chloroacetamide compounds had herbicidal activity. During the 1960s and 1970s, amide herbicides developed rapidly, and most varieties were commercialized during this period. Alachlor and metolachlor are typical representatives. With the progress of society and the enhancement of environmental awareness, chiral pesticides have also become a very active research field in pesticide chemistry. (S)-Metolachlor is a typical product among chloroacetamide herbicides. This product is a widely used herbicide. The traditionally used metolachlor is a racemate, only Half of the ingredients have herbicidal effect, and the active ingredient is its S isomer, which accounts for about 50%, while the other 50% o...

Claims

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Application Information

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IPC IPC(8): C07C233/25C07C231/02C07C231/12A01P13/00
Inventor 朱红军李玉峰陈巍于国权杜刚吕良忠楚庆岩
Owner NANJING UNIV OF TECH
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