Diastereoselective reduction and carboncarbon bond formation of α-keto esters/amides with SmI2

The stereoselective reduction of α-keto esters/α-keto amides, which have various chiral auxiliaries using SmI2, is examined. 2(S)-Methoxymethylpyrrolidine, 1,1,2(S)- and 1,1,2(R)-triphenylethanediol were found to be suitable chiral auxiliaries that produced the corresponding α-hydroxy ester and amide in good diastereoselectivity with satisfactory yields. Allylation, the Reformatsky-type reaction, and the ketyl-alkene coupling reaction with the 1,1,2(R)-triphenylethanediol and 2(S)-methoxymethyl-pyrrolidine, derivative of the α-keto ester/amide proceeded smoothly with high diastereoselectivity.