Cycloaddition of Pyridinium Methylides with Electron-Deficient Olefins and Silica-Gel Mediated Elimination of Pyridines from the Cycloadducts: A New Method of Alkylation or Hydroalkylidenation of Olefins

Abstract

Pyridinium methylides bearing an anion-stabilizing substituent at the ylide carbon react with a variety of olefins carrying two electron-withdrawing groups at the both carbons such as N-substituted maleimides, a citraconimide, dimethyl maleate, dimethyl fumarate, and 1,2-dibenzoylethene. The cycloadducts thus formed undergo a ready elimination of pyridines when treated with silica gel. This sequence is a new method for alkylation or hydroalkylidenation of olefins.