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Communication | Regular issue | Vol 32, No. 7, 1991, pp.1279-1282
Published online, 1st January, 1970
DOI: 10.3987/COM-91-5765
Synthetic Studies on Podophyllum Lignans: Tributyltin Hydride-induced Radical Cyclization and Intramolecular Heck Reaction of α-Benzylidene-β-(o-bromobenzyl)-γ-lactones

Hiroyuki Ishibashi,* Katsuhiro Ito, Masayo Tabuchi, and Masazumi Ikeda*

*Kyoto Pharmaceutical University, Misasagi-Shichonocho, Yamashina, Kyoto 607-8414, Japan

Abstract

Tributyltin hydride-induced radical cyclization of the (Z)-α-benzylidene-β-(o-bromobenzyl)-γ-lactone (16) gave the 6-endo cyclization product, (±)-deoxyisopicropodophyllin (18), and the 5-exo cyclization product (19). On the other hand, the intramolecular Heck reaction of 16 provided (±)-γ-apopicropodophyllin (20) as a sole cyclization product.