Sulfur-Directed Regioselective Radical Cyclization Leading to. beta.-Lactams: Formal Synthesis of (.+-.)-PS-5 and (+)-Thienamycin

H Ishibashi, C Kameoka, H Iriyama…

Index: Ishibashi; Kameoka; Iriyama; Kodama; Sato; Ikeda Journal of Organic Chemistry, 1995 , vol. 60, # 5 p. 1276 - 1284

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Citation Number: 76

Abstract

BuaSnH in the presence of azobis (isobutyronitri1e)(AIBN) in boiling toluene, underwent radical cyclization in a 4-exo-trig manner to give p-lactam 13, but in low yield (22%), whereas N-[2, 2-bis-(pheny1thio) ethenyll congener 23 cyclized with a high degree of effeciency to give p-lactam 25 and a partially desulfurized lactam 13 in 70% combined yield. The effectiveness of the 4-exo cyclization of 23 can be explained in terms of the high ...