Preparation of differentially 1,3-disubstituted indolines by intramolecular carbolithiation

The ether-soluble dilithio species (2), derived from N-allyl-2-bromoaniline (1) upon treatment with t-BuLi at −78°C, cyclizes when warmed to +5°C in the presence of TMEDA to give a (1-lithio-3-indolinyl)methyllithium (3) that may be differentially functionalized by sequential addition of electrophiles. The cyclization of 2 to 3 proceeds enantioselectively when conducted in the presence of (1S,2S)-(+)-N,O-dimethylpseudoephedrine.