1-ナフチルホスフィンから誘導されるビニルロジウム錯体におけるアルキンのβ-炭素脱離

概要

The migratory insertion of an unsaturated bond into a metal−carbon bond represents a prevalent elementary step in organometallic chemistry. Its reverse process, namely β-carbon elimination, has also attracted increasing attention in recent years, because this process can provide unique methods for the activation of a C−C bond. However, despite of many reports on βcarbon elimination reactions of alkyl–alkoxometal complexes, those of alkenylmetal species, the reverse processes of alkyne insertion, have scarcely been reported. Pioneering work by Etienne et al. showed that the R/R’ exchange reaction of an alkylniobium complex [Tp*NbCl(R)(R’C≡CR”)] proceeds via the sequential alkyne insertion–β-carbon elimination.1 This laboratory also reported specific examples using late transition metals, where the alkyne insertion–βcarbon elimination process competes with the vinylidene rearrangement of the alkyne.2,3 However, fundamental characteristics of this reaction still remain to be investigated. In this study, the author has focused his attention on more direct observation of the β-carbon elimination from alkenylmetal complexes to give alkynes, and found that a new rhodium complexes derived from 1-naphtylphosphine and PhC≡CPh is capable of alkenyl moiety exchange reaction under very mild conditions via β-carbon elimination.