Asymmetric synthesis of α,α-dibranched propargylamines by acetylide additions to N-tert-butanesulfinyl ketimines

Addition of lithium acetylides prepared from 1-pentyne, phenylacetylene, and trimethylsilylacetylene to diverse N-tert-butanesulfinyl ketimines affords a range of alpha, alpha-dibranched propargyl sulfinamides in generally good yields (up to 87%) and with high diastereoselectivities (up to > 99: 1). Acidic cleavage of the tert-butanesulfinyl group provides the free alpha, alpha-dibranched propargylamines.