HETERO DIELS-ALDER TYPE REACTIONS BETWEEN DANISHEFSKY'S DIENES IN THE PRESENCE OF LEWIS BASE CATALYSTS. AN EFFICIENT METHOD FOR THE SYNTHESIS OF SUBSTITUTED 2,3-DIHYDROPYRAN-4-ONES

摘要

Abstract - Alkoxy anion such as methoxide anion works effectively as Lewis base catalyst to activate silicon-carbon bond of l-methoxy-3-trimethylsilyl-oxy-l,3-butadiens (Danishefsky's dienes) in the reaction between aldehydes and ketones. By using Lewis base as catalyst, acid sensitive substrates and Lewis basic moiety containing substrates can be used in this reaction. The hetero Diels-Alder type reaction proceeds through stepwise mechanism between silyl enolates and carbonyl compounds.