Abstract
tert-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-trifluoromethylamines are efficiently synthesized using this methodology.
