Diastereoselective allylation of chiral sulfinyl-substituted thiophenecarbaldehydes with a Lewis acid

Abstract

Diastereoselective allylation of the optically active sulfinyl-substituted thiophenecarbaldehydes 3–5 with allyltriphenylstannane in the presence of a Lewis acid has been examined. Allylation of compounds 4 and 5 in the presence of titanium(IV) tetrachloride produced the addition products 11 and 13, respectively, with good diastereoisomeric excesses (de's), whereas in the presence of tin(IV) tetrachloride the corresponding diastereoisomers 12 and 14, respectively, were obtained. Allylation of compound 5 mediated by ytterbium triflate occurred with excellent diastereoselectivity (96% de) under conventional conditions.