Applications of modified Wittig reaction to butatriene synthesis

摘要

The preparation of allenes by the condensation of an acyl chloride with a phosphonium ylid and subsequent elimination of an acid salt and a phosphonium oxide has been established by Bestmann and Hartung. It was felt that this process could be expanded to include the synthesis of butatrienes. Butatrienes are stabilized by aromatic substituents while aromatic substituents decrease the nucleophilicity and reactivity of the phosphonium ylids to be used in the synthesis of the butatrienes. The ylids employed were carbomethoxyphenylmethylenetriphenyl phosphorane, and a new compound, carbethoxyphenylmethylenetriphenyl phosphorane, both of which failed to form alkylated condensation products. Both ylids were prepared by the u22meltu22 method which gave better yields than comparable processes in dry benzene. The salt of a third ylid, carbethoxyphenylmethylenetrimethylphosphonium chloride - a new compound, was also prepared. However, the process for the preparation of this salt was not consistently reproducable and gave only low yields. A previously unreported reaction involving the condensation of ethyl diethylphosphonoacetate and benzoyl chloride was carried out and led to the formation of ethyl phenylpropynoate as was proposed.