Asymmetric Synthesis of α-Alkylated N-Sulfinyl Imidates as New Chiral Building Blocks

Abstract

Alpha-alkylation of N-sulfinyl imidates, prepared via condensation of tert-butanesulfinamide with ortho esters, led to alpha-substituted N-sulfinyl imidates in good-to-excellent diastereomeric ratios (dr up to >99:1) and yields. Deprotection of the alkylated N-sulfinyl imidates gave access to the corresponding imidate hydrochlorides in outstanding yields. These imidate hydrochlorides proved to be excellent intermediates for an easy transformation to chiral amides in good yields and enantiomeric excess upon simple heating in chloroform. Hydrolysis of the alpha-benzylated imidate hydrochlorides afforded the corresponding chiral esters with >95% ee.