NiIICl(1-Naphthyl)(PCy3)2, An Air-Stable σ-NiII Precatalyst for Quantitative Cross-Coupling of Aryl C–O Electrophiles with Aryl Neopentylglycolboronates

Abstract

Advances in nickel catalysis have enabled the employment of the widely available and environmentally benign phenol derivatives as aryl electrophiles in Suzuki–Miyaura cross-coupling reactions. NiII-phosphine complexes such as NiIICl2(PPh3)2, NiIICl2(dppf), NiIICl2(dppe), NiIICl2(dppp), NiIICl2(PCy3)2 and π-Ni0 complexes, the classic being Ni(COD)2/PCy3, both classes mostly in the presence of a mixed ligand, are some of the most successful precatalysts employed in the cross-coupling of aryl mesylates, sulfamates, carboxylic esters, carbonates, carbamates and methyl ethers with aryl boronic acids, boroxines and neopentylglycolboronates. Here we report that the highly reactive but bench-stable σ-NiII complex, NiIICl(1-naphthyl)(PCy3)2 (where σ refers to the Ni–C bond), exhibits higher efficiency than all previously reported precatalysts and facilitates the quantitative cross-coupling of all six C–O electrophiles mentioned above in reaction times of 0.5 to 24 hours.