Nucleophilic Addition of Regioselectively Lithiated Indoline with Aldimines for the Syntheses of 2- and 7-Indolinyl Methanamine Derivatives

Indolines bearing different N-protecting groups (N-Tbf and N-Boc) were deprotonated regioselectively at C-2 (sp3 hybridized ortho-H) and C-7 (sp2 hybridized para-H) of the indoline ring, respectively. The generated organolithium intermediates reacted with aldimines to give the desired products in good yields with excellent anti-diastereoselectivities (>99:1). The produced N-Ts-(1-Tbf-indolin-2-yl)methanamine was facilely transformed to a fused heterocyclic compound.