α-(Arylsulfonamido)borneols as Auxiliaries in Asymmetric Synthesis: An Efficient and Highly Stereoselective Method for the Reduction of α-Keto Esters

Article abstract of DOI:10.1021/jo00057a004

A method for preparation of enantiomerically pure α-hydroxy esters by stereoselective reduction of chiral α-keto esters under convenient conditions (LiAlH(OCEt3)3, THF, 0 deg C) has been developed.The compounds exo,exo-3-(arylsulfonamido)-2-borneol and exo,exo-2-(arylsulfonamido)-3-borneol have been used as novel auxiliaries to achieve highly diastereoselective reductions.The auxiliaries can be removed by mild saponification (LiOH, THF-H2O, rt) without racemization of the reduced products.