7-<i>endo</i> Selective Aryl Radical Cyclization onto Enamides Leading to 3-Benzazepines: Concise Construction of a Cephalotaxine Skeleton
作者:Tsuyoshi Taniguchi、Atsuko Ishita、Masahiko Uchiyama、Osamu Tamura、Osamu Muraoka、Genzoh Tanabe、Hiroyuki Ishibashi
DOI:10.1021/jo040264u
日期:2005.3.1
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-endo cyclization products. These results indicated that the position of the carbonyl group on enamide played an important role in deciding the course of the cyclization. The 7-endo selective cyclization was applied to concise construction of a cephalotaxine skeleton.