Highly diastereoselective addition of silyldihalomethyllithiums to chiral alkyl esters

Treatment of benzoate, formate, or trifluoroacetate esters with silyldibromomethyllithiums provides alkyl silyl mixed acetals via the 1,3-rearrangement of a silyl group from carbon to oxygen. A high level of asymmetric induction onto the acetal carbon is observed when chiral alkyl esters are employed. The stereochemical assignment of the silyl acetal 13j was accomplished on the basis of X-ray crystallographic analysis. A one-pot synthesis of a three-component coupling product R(1)C(OR(2))(OSiMe(2)-t-Bu)CX(2)E' (X = Cl, Br) by sequential additions of an ester (R(1)CO(2)R(2)) and the second electrophile was achieved.