Pd/Pivalic Acid Mediated Direct Arylation of 2-Pyrones and Related Heterocycles

Direct arylation represents a favourable alternative to traditional cross-coupling reactions and has found widespread use with simple aryls and robust heterocycles. Herein a direct arylation protocol has been optimised and applied to more delicate, privileged biological motifs. The intramolecular direct arylation of 2-pyrones, 2-coumarins, 2-pyridones and 2-quinolones occurs in very good to excellent yields using a Pd-0 source and pivalic acid as a crucial additive. Preliminary mechanistic investigations were also carried out.