7-Endo selective aryl radical cyclization onto enamides leading to 3-benzazepines: Concise construction of a cephalotaxine skeleton
(Chemical Equation Presented) Bu3SnH-mediated radical cyclizations of 2-(2-bromophenyl)-N-ethenylacetamide gave 6-exo cyclization product 15 as the major product, whereas N-[2-(2-bromophenyl)ethyl]-N- ethenylamides gave almost exclusively 7-end