Catalysis of the Suzuki reaction by acyclic diaminocarbene palladium complexes generated in situ

Abstract

Acyclic diaminocarbene palladium complexes generated in situ by nucleophilic attack of morpholine, 4-nitrophenylhydrazine, or benzhydrazide on bis(isocyanide) palladium(II) complexes catalyzed the Suzuki reaction of 4-iodo- or 4-bromoanisole with phenylboronic acid. Morpholine turned out to be the best catalyst modifier. The cross coupling reaction under fairly mild conditions (reflux in ethanol in the presence of potassium carbonate) in 2 h afforded 4-methoxybiphenyl whose yield was insignificantly lower than in the presence of preliminarily prepared catalyst. Neither preliminary degassing nor protection from atmospheric moisture and oxygen was necessary.