N-tert-butanesulfinyl imines: Versatile intermediates for the asymmetric synthesis of amines

Abstract

N-tert-Butanesulfinyl aldimines 3 and ketimines 4 are exceedingly versatile intermediates for the asymmetric synthesis of amines. The N-tert-butanesulfinyl imines are prepared in high yields by condensing enantiomerically pure tert-butanesulfinamide 1, which is readily available in either configuration, with a wide range of aldehydes and ketones. The tert-butanesulfinyl group activates the imines for the addition of many different classes of nucleophiles, serves as a powerful chiral directing group, and after nucleophilic addition is readily cleaved by treatment of the product with acid. A wide range of highly enantioenriched amines, including α-branched and α,α-dibranched amines, α- and β-amino acids, 1,2- and 1,3-amino alcohols, and α-trifluoromethyl amines, are efficiently synthesized using this methodology. In addition, N-tertbutanesulfinyl imine derivatives provide a new family of ligands for asymmetric catalysis.