Palladium-Catalyzed Aminocarbonylation in Solid-Phase Peptide Synthesis: A Method for Capping, Cyclization, and Isotope Labeling.

A new synthetic approach for introducing N-capping groups onto peptides attached to a solid support, combining aminocarbonylation under mild conditions using a palladacycle precatalyst and solid-phase peptide synthesis, is reported. The use of a silacarboxylic acid as an in situ CO-releasing molecule allowed the reaction to be performed in a single vial. The method also enables versatile substitution of side chains, side-chain-to-side-chain cyclizations, and selective [13C] acyl labeling of modified peptides.