Rhodium-catalysed Anomalous Dimerization Of Styrenes Involving The Cleavage Of The Ortho C-h Bond

摘要

The dimerization of styrene derivatives in the presence of a rhodium catalyst proceeds to give stilbene derivatives, in which the ortho C-H bond of styrenes is cleaved and functionalized.rnTransition metal-catalysed dimerization of alkenes represents an industrially important process for preparing higher alkenes from simple and small alkenes. In addition to the practical importance, the mechanistic aspects of these dimerization processes have received much attention as a model system for the polymerization and oligomerization of alkenes. Among the alkenes for use in catalytic dimerization, styrene derivatives have been extensively studied. Catalytic dimerization of styrenes generally produces a head-to-tail isomer, while there are a few reports on catalyst systems that can afford tail-to-tail or head-to-head isomers in a regioselective manner (Scheme 1). Although the regiochemical outcome depends on the catalyst system employed, a new carbon-carbon bond is formed between the vinylic carbons in all reported systems. Herein, we report a new mode for the catalytic dimerization of styrenes, in which the new carbon-carbon bond is formed between the benzene ring at the 2-position and the vinylic carbon.