Suzuki cross-coupling reactions of aryl chlorides using [Cl2Pd(COD)]/piperazine derivative under microwave conditions

Efficient Suzuki⁻Miyaura C-C Cross-Couplings Induced by Novel Heterodinuclear Pd-bpydc-Ln Scaffolds

An easy access to a series of previously unreported heterodinuclear Pd-Ln compounds, Pd-bpydc-La, Pd-bpydc-Ce and Pd-bpydc-Nd (bpydc = 2,2'-bipyridine-5,5'-dicarboxylate) has been developed. The Pd-Ln hybrid networks were effectively applied as catalysts in Suzuki⁻Miyaura C-C cross-coupling reactions of 4-bromoanisole and 4-bromobenzonitrile with phenylboronic acid, under mild conditions. A systematic investigation revealed Pd-bpydc-Nd as the most active catalyst. In all cases, reaction yields varied with the base, catalyst loading and substantially augmented with temperature (from 30 to 60 °C). Substituent effects were operative when changing from 4-bromoanisole to 4-bromobenzonitrile. The key role played by the lanthanides, aromatic substrate and base, in modulating the Pd-catalytic cycle has been highlighted. Importantly, the new catalysts proved to be stable in air and vs. functionalities and are quite efficient in Suzuki⁻Miyaura carbon-carbon bond formation conducted in protic solvents.

A 2-((4-Arylpiperazin-1-yl)methyl)phenol ligated Pd(ii) complex: an efficient, versatile catalyst for Suzuki–Miyaura cross-coupling reactions

N,N,O-Tridentate palladium(ii) complex 4a was found to be an efficient catalyst for the Suzuki cross-coupling reaction of aryl halides (iodo-, bromo- and chloro-), which afforded cross-coupling products in good to excellent yields.