Sulfinimine-mediated asymmetric synthesis of 1,3-disubstituted tetrahydroisoquinolines: a stereoselective synthesis of cis- and trans-6,8-dimethoxy-1,3-dimethyl-1,2,3,4-tetrahydroisoquinoline.

[reaction: see text] The highly diastereoselective addition of lateral lithiated o-tolunitriles to sulfinimines followed by treatment of the resulting sulfinamide with MeLi, hydrolysis, and reduction represents a concise new methodology for the asymmetric synthesis of 1,3-disubstituted tetrahydroisoquinolines.