SYNTHESIS OF 3-VINYLPIPERIDINES, 3-ETHYLIDENEPIPERIDINES AND 5-FUNCTIONALIZED-1,2,3,4-TETRAHYDROPYRIDINES

Reaction of 1-azapentadienyl anions, generated by deprotonation of N-( 2-buten-1-ylidene)alkylamines, with 1-bromo-3-chloropropane led to the formation of [2-(3-chloropropyl)-3-buten-1-ylidene]alkylamines. By re action with nucleophiles and bases, the latter functionalized imines w ere converted into unsaturated piperidines, i.e. 3-vinylpiperidines, 3 -ethylidenepiperidines, 5-vinyl-1,2,3,4-tetrahydropyridines and 5-(2-c yanoethyl)-1,2,3,4-tetrahydropyridines. 5-Vinyl-1,2,3,4-tetrahydropyri dines proved to be suitable dienes in Diels-Alder reactions with N-phe nylmaleimide, giving rise to octahydro-1H-pyrrolo[3,4h]quinoline-1,3-d iones. (C) 1998 Elsevier Science Ltd. All rights reserved.