Abstract
The effect of silicon on C-C bond formation between carbonyl compounds and allyltrimethylsilane was investigated. Treatment of 1,3-diketones, β-ketoesters or malonates with allyltrimethylsilane in the presence of ceric ammonium nitrate (CAN) in methanol produced the corresponding allylated products. Furthermore, introduction of Mn(OAc) 3 · 2H 2 O into those reactions for replacement or assistance of CAN afforded silicon-containing cyclopentanes in 51-75% yields. A sequential process involving allylation, free-radical cyclization and elimination was also developed by use of CAN/Mn (OAc) 3 · 2H 2 O/Cu(OAc) 2 · H 2 O. Accordingly, β-ketoesters or malonates were allowed to react with allylsilanes in acetic acid to give silicon-containing cyclopentanes with an exo methylene unit in 52-71% yields. These reactions involved carbocationic and carboradical intermediates, of which formation and chemical activities were controlled by a β-silyl group. © 1997 by John Wiley & Sons, Ltd.