Synthesis of tricyclic oxazinoindolones via Pd-catalyzed intramolecular addition of carboxylic acids to alkynes

Abstract

A completely atom-economical synthesis of the oxazinoindolone core via the Pd-catalyzed intramolecular addition of carboxylic acids to alkynes has been developed. Oxazinoindolones have been known to have varied biological activities. The reaction proceeds via 6-exo-dig cyclization and affords the products in high yields (55–93%). The developed method demonstrates the applicability of a Pd(0) complex in combination with a substrate-tethered acid for the 1,2-addition of carboxylic acids to alkynes.