Diastereoselective Aza-Mislow-Evans Rearrangement of N-Acyl tert-Butanesulfinamides into alpha-Sulfenyloxy Carboxamides

摘要

A diastereoselective [2,3] rearrangement of O-silyl N-sulfinyl N,O-ketene acetals derived from chiral N-acyl tert-butanesulfinamides was developed, giving alpha-sulfenyloxy car-boxamides with excellent enantioselectivity. Enolization and subsequent silylation of N-acyl tert-butanesulfinamides initiate this aza variant of the Mislow-Evans rearrangement, in which the chirality at the sulfur atom in the rearrangement precursors is faithfully transferred to the alpha-carbon stereocenter of the products. The Ellman sulfinamide, often used as a chiral ammonia equivalent, can serve in this rearrangement as a chiral precursor for the asymmetric synthesis of alpha-oxygen-functionalized carboxamides.