[4 + 2]‐Cycloadditionen von α,β‐ungesättigten Hydrazonen. Teil 1. Pyridin‐2,3‐dicarboximide aus 1‐(Dimethylamino)‐1,4‐dihydropyridin‐Derivaten

Abstract

[4 + 2] Cycloadditions of α,β‐Unsaturated Hydrazones to Pyridine‐2,3‐dicarboximides via 1‐(Dimethylamino)‐1,4‐dihydropyridine Derivatives The [4 + 2] Cycloaddition of α,β‐unsaturated hydrazones of type 1 (1‐aza‐1,3‐butadienes) with 2‐halogenomaleimides 4 affords 1,4‐dihydropyridines 6 which, after treatment with an acid, yield highly substituted pyridine‐2,3‐dicarboximide derivatives 7 ( Scheme 1 ).