Indium(III) Chloride/Chlorotrimethylsilane as a Highly Active Lewis Acid Catalyst System for the Sakurai−Hosomi Reaction

The indium(III) chloride/chlorotrimethylsilane system acts as a catalyst for the Sakurai−Hosomi reaction between allylsilanes and aldehydes. When γ-substituted allylsilanes such as crotylsilane and prenylsilane are used a high regioselectivity for γ-addition is observed. Smaller amounts of the catalyst (5 mol %) effectively afforded the allylation products, although larger amounts (20 mol %) gave no product whatsoever. Other group 13 Lewis acids such as AlCl3 and BF3·OEt2 did not have catalytic activity even when combined with chlorotrimethylsilane. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)