Efficient, Nickel‐Catalysed Kumada–Tamao–Corriu Cross‐ Coupling with a Calix[4]arene‐Diphosphine Ligand

Abstract

Abstractmagnified imageThe dynamic complex cis‐P,P′‐(η5‐cyclopentadienyl)‐{5,17‐bis(diphenylphosphino)‐25,26,27, 28‐tetrabenzyloxycalix[4]arene}nickel(II) tetrafluoroborate (2) in which the PNiP plane undergoes a rapid fanning motion was assessed in the cross‐coupling reacting between phenylmagnesium bromide (PhMgBr) and aryl halides (ArX). TOFs, of up to 21250 mol(converted ArBr)⋅mol(2)−1⋅h−1, were obtained with electron‐rich as well as congested bromoarenes using catalyst loadings as low as 1×10−3 mol%, provided that the reactions were carried out at 100 °C in dioxane with a PhMgBr/ArX ratio of 2:1. The high activities observed contrast with those observed for triphenylphosphine‐based catalysts and furthermore, outperforms the fastest diphosphine‐based catalysts reported, a behaviour which is likely to rely on a bite angle effect.