New perspectives of carbo - and hetero - I , 3 - dienes in organic synthesis

The preparation and reactivity of 4-amino-1 -azadienes and electronically neutral 2-azadienes is reported. The suitability of the 1 -azadiene system for the synthesis of five-, six-, seven-, and eight-membered as well as the synthetic utility of 2-azadienes through [4+2] cycloadditions is presented. For some years the azadiene derivatives have attracted our attention due to their utility as synthetic intermediates. In this lecture we are going to give you some recent achievements in synthesis of nitrogen-containing cyclic and acyclic compounds starting from 4-amino-1 -azaand 2-aza1,3dienes (Figure 1). I-AnhO-l-erS-l,3-&W 2-k.-1,3-&M 4-amino-1-azabutadienes These systems are prepared in quantitative yields by heating at 60" C a THF mixture of ketimine, saturated nitrile, and aluminium chloride, as outlined in Scheme 1 (ref. 1). Azadienes derived from aldimines (R2-H) are synthesized using LDA, as reported by Wittig (ref. 2). Hydrolysis of both imine and enamine groups leads cleanly to C-substituted 1,3-diketones (ref. 3).