A new synthesis of α,α-disubstituted carbonyl compounds from carbonyl compounds with one-carbon homologation

Lithium alpha-sulfinyl carbanions of 1-chloroalkyl p-tolyl sulfoxides were reacted with carbonyl compounds to afford adducts in high to quantitative yields. The adducts were treated with t-BuMgCl or LDA to give magnesium or lithium alkoxides, which were treated with i-PrMgCl or t-BuLi to afford the enolate with one-carbon elongation through beta-oxido carbenoids. The enolate intermediates were found to be able to be trapped with electrophiles to give alpha,alpha-disubstituted carbonyl compounds in moderate to good yields. As a whole, this procedure offers a new and good method for synthesis of alpha,alpha-disubstituted carbonyl compounds from carbonyl Compounds with one-carbon homologation in only two synthetic steps. (C) 2004 Elsevier Ltd. All rights reserved.