| 摘要 |
<p>Novel gamma -lactone derivatives are provided. These lactone derivatives, when reacted with hydrogen halide in alcohol, yield gamma -halogeno- delta -unsaturated carboxylic acid esters. This ring-opening process is useful for the purpose of increasing the yield of pyrethrin analogs which are of value as insecticides and agricultural chemicals. Thus, the gamma -lactone derivatives by-produced in the production process for dihalogenovinyl chrysanthemumates are caused to undergo ring-opening reaction to yield the corresponding gamma -halogeno- delta -unsaturated carboxylic acid esters which are important intermediates for said pyrethrin analogs.</p> |
