Selective C‑2 Alkylation of Tryptophan by a Pd(II)/Norbornene-Promoted C–H Activation Reaction

A palladium­(II)-catalyzed norbornene-mediated regioselective alkylation at the C-2 indole position of N-tert-butyloxycarbonyl (Boc)-protected (S)-tryptophan ethyl ester is reported. The protocol employs mild reaction conditions and is tolerant of a range of functional groups. The reaction proceeds without racemization at the stereogenic center of the amino acid.