AZA-WITTIG REACTION OF N-VINYLIC PHOSPHAZENES WITH CARBONYL-COMPOUNDS- AZADIENE-MEDIATED SYNTHESIS OF DIHYDROPYRIDINES AND PYRIDINES

Aza-Wittig reaction of N-vinylic phosphazenes derived from diphenylmet hylphosphine 4 with carbonyl compounds leads to the formation of 2-aza dienes derived from beta-amiuoacids 5. Dimerization of 2-azadienes 5c, d and reaction of compounds 5 with phosphazene 4 or enemine 6 affords substituted dihydropyridines 7 and 8. Aza-Wittig reaction of phosphaze nes 4 with alpha,beta-unsaturated aldehydes gives 3-azatrienes 12, whi ch are easily converted into pyridines 13. Copyright (C) 1996 Elsevier Science Ltd