| 摘要 |
PURPOSE:To prepare the titled compound useful as a raw material of pyrethroidal insecticides, easily, in high yield, in an industrial scale, at a lower reaction temperature than conventional process, by treating a cis or cis/trans-mixture of chrysanthemumic acid alkyl ester with a Lewis acid as a catalyst. CONSTITUTION:The 2,2-dimethyl-3-(2-methyl-1-propenyl)-1,3-cis-cyclopropane-1- carboxylic acid alkyl ester of formulaI(R is alkyl) (cis-chrysanthemumic acid alkyl ester) or a mixture of said cis-compound with the trans-chrysanthemumic acid alkyl ester of formula II is converted to trans-chrysanthemumic acid alkyl ester using a Lewis acid (e.g. boron trifuoride etherate, iron chloride, etc.) as a catalyst, at -70-+150 deg.C, preferably -30-+100 deg.C. The conversion to the trans- compound proceeds independent of the external pressure without retarding the reaction. |
