Oxime-Derived Palladium Complexes as Very Efficient Catalysts for the Heck–Mizoroki Reaction

Abstract

Oxime-derived, chloro-bridged palladacycles 16 are efficient complexes for the Heck vinylation of aryl halides. The isolated catalysts are thermally stable, not sensitive to air or moisture and easily accessible from inexpensive starting materials. The reaction can be performed under aerobic conditions, with aryl iodides, bromides and chlorides with acrylic esters and olefins displaying turnover numbers (TON) of up to 1010 for phenyl iodide and turnover frequencies (TOF) of 1.4×108 h−1. Deactivated aryl bromides undergo the Heck reaction with styrene with TON and TOF values up to 97,000 and 6063 h−1, respectively. Even aryl chlorides undergo the coupling reaction with olefins with TON up to 920. Complexes 16 catalyze the synthesis of 2,3-disubstituted indenones and indoles in good yields via annulation reaction of internal alkynes with o-bromo- or o-chlorobenzaldehyde and o-iodoaniline, respectively.