A three-step process for the production of chrysanthemic acid esters and their homologues of the formula: ##STR1## in which R.sub.1 and R.sub.2 are hydrogen or C.sub.1 -C.sub.6 alkyl, R.sub.3 and R.sub.4 are C.sub.1 -C.sub.6 alkyl or halogen or, together with the C atom to which they are attached, form a cycloalkyl group, and R.sub.5 is C.sub.1 -C.sub.6 alkyl, Which comprises: (1) decarboxylating a lactone of the formula: ##STR2## (2) treating the resulting decarboxylated lactone to effect ring cleavage, halogenation and esterification to form an ester of the formula: ##STR3## in which X is Cl, Br or I, and (3) TREATING THE ESTER X with a base to effect internal condensation whereby the desired product of formula I is obtained. The esters I are valuable intermediates for the preparation of synthetic pyrethroids having insecticidal activity.
一种制备
菊酸酯及其同系物的三步反应过程,其
化学式为:##STR1## 其中R.sub.1和R.sub.2为氢或C.sub.1-C.sub.6烷基,R.sub.3和R.sub.4为C.sub.1-C.sub.6烷基或卤素,或与它们所连接的C原子一起形成环烷基,R.sub.5为C.sub.1-C.sub.6烷基。该过程包括:(1)脱羧化上述
化学式的内酯,(2)处理所得的脱羧内酯以实现环裂解、卤化和酯化,形成上述
化学式中X为Cl、Br或I的酯,(3)用碱处理酯X以实现内部缩合,从而得到所需的
化学式I的产物。化合物I是制备具有杀虫活性的合成拟
除虫菊酯的有价值的中间体。