Extremely Efficient Chiral Induction in Conjugate Additions of p-Tolyl α-Lithio-β-(trimethylsilyl)ethyl Sulfoxide and Subsequent Electrophilic Trapping Reactions.

Reaction of p-tolyl α-lithio-β-(trimethylsilyl)ethyl sulfoxide with α,β-unsaturated esters gave the conjugate addition products as a single diastereomer. The intermediate enolates were subsequently trapped with various alkyl halides or aldehydes to give the products with extremely high stereoselectivity. The reaction with α,β-unsaturated ketones also proceeded with high diastereoselectivity. Protolysis of the enolates derived from the α-methyl-α,β-unsaturated esters gave the products with high stereoselectivity. The stereo- and regioselective elimination of the sulfinyl group gave chiral homoallylic carboxylates.