| 摘要 |
The asymmetric synthesis of esters of 2,2-dimethyl-3-(2,2,2-trichloroethyl)cyclopropanecarboxylic acid and 2,2-dimethyl-3-(2,2,2-tribromoethyl)cyclopropanecarboxylic acid is carried out by reacting 1,1,1-trichloro-4-methyl-3-pentene or 1,1,1-tribromo-4-methyl-3-pentene, respectively, with a diazo acetate of the formula: N2CHCOOR (II> in which R is an alkyl, cycloalkyl, methyl, neomenthyl or aralkyl radical in the presence of a chiral copper catalyst of the formula <IMAGE> in which the asterisk (<*>) denotes an asymmetric carbon atom, R1 denotes an alkyl radical, a benzyl radical, an alkoxy-substituted benzyl radical or a benzyloxy-substituted benzyl radical and R2 denotes an unsubstituted aryl radical, an alkoxy- or benzyloxy-substituted aryl radical, an alkyl- or aryl-substituted phenyl radical or a phenyl radical having an alkoxy or benzyloxy group in the 2 position and an alkyl or aryl group in the 5 position. The optically active esters prepared in this way can be used to prepare optically active 2,2-dimethyl-3-(2,2-dichlorovinyl)- or 2,2-dimethyl-3-(2,2-dibromovinyl)cyclopropanecarboxylic acid. These acids are starting materials for the production of insecticides.
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