Efficient Preparation of 1,3-Butadiene and Cyclohexene Derivatives Possessing 2-Aminomethyl Group through Indium-Mediated 1,3-Butadien-2-ylation

Abstract

Nucleophilic addition reactions of carbon nucleophiles to imines is essential for synthesizing biologically active hetero- cyclic compounds. 1 While addition reactions of various carbon nucleophiles to carbonyl compounds have been reported, con- siderably less successful results were obtained in the analogous addition reactions with imines due to relatively low reactivity of unactivated imines towards nucleophilic addition and de- protonation of imines. During the last decades, various carbon nucleophiles have been used in addition reactions of imines. 2 However, the preparation of 2-aminomethy-1,3-dienes via addi- tion reaction of 1,3-butadien-2-yl moiety to imines is still rare. Of these, Grignard cross-coupling reaction of 2-bromo-3-amino- propene with vinyl bromides suffers from poor chemoselec- tivity. 3 2-Halomethyl-1,3-diene though quite effective in react- ing with 2-amines to give 2-aminomethyl-1,3-dienes are not convenient to prepare.