P-Directed Borylation of Phenols

Abstract

Internal borylation occurs upon activation of aryl di-isopropylphosphinite boranes with HNTf(2) to give heterocyclic intermediates that can be reductively quenched to afford 6 or treated with KHF(2) to give the phenolic potassium aryl trifluoroborate salts 10. The latter salts are useful for Pd-catalyzed coupling with aryl iodides under Molander conditions, provided that precautions are taken to remove the KNTf(2) byproduct from the preceding KHF(2) step.