β- and γ-lactams by nickel powder mediated 4-exo or 5-endo radical cyclisations. A concise construction of the mesembrine skeleton
作者:Jérôme Cassayre、Béatrice Quiclet-Sire、Jean-Baptiste Saunier、Samir Z. Zard
DOI:10.1016/s0040-4020(97)10204-6
日期:1998.2
N-Alkenyl trichloroacetamides, upon treatment with nickelpowder and aceticacid in refluxing 2-propanol undergo reversible 4-exo radicalcyclisation. The cyclised radical can be trapped in different ways leading to β-lactams. When the trap is omitted or not efficient enough, unusual irreversible 5-endo cyclisation occurs affording functionalised five-membered lactams. Synthesis of bicyclic γ-lactams