Asymmetric Synthesis of Amines with tert-Butanesulfinamide and Its Application

Butanesulfinyl imines are exceedingly versatile intermediates for the asymmetric synthesis of amines. Aldimines 15 and ketimines 16 are prepared in high yields under mild conditions by condensing enantiomerically pure tert-butanesulfinamide 10, either enantiomer of which is readily synthesized in large scale from inexpensive reagents, 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 function as a versatile protecting group of the amines, which is readily cleaved by treatment with acid. A wide range of highly enantioenriched amines, including α-branched amines, 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.