Addition des organocadmiens aux composés carbonylés α,β-éthyléniques: étude des réactions compétitives des énolates intermédiaires

Abstract

We have formerly investigated the reactions of organocadmium compounds (in the presence of magnesium halides) with α,β-unsaturated carbonyl compounds. The results show that 1,2 and 1,4-addition reactions take place, however, the cadmium compounds favour 1,4-addition in many cases. The primary “1,4-enolates” can add to the original α,β-unsaturated carbonyl compound: they undergo 1,4-addition to ketones giving δ-diketones; and 1,2-addition to aldehydes thus forming an alcoholate with an aldehyde group which then condenses with the organocadmium compound. The final product is an unsaturated β-glycol. With “1,2-alcoholates”, however, we did not observe such reactions. We have studied the influence of various factors on the course of these reactions. Thus, in the presence of CuX, the 1,4-addition product is predominant and only small amounts of 1,4-addition products from enolates are formed.