Ruthenium-Catalyzed Vinylic Substitution Reactions with Nucleophiles via Butatrienylidene Intermediates

摘要

Transition metal complexes of cumulated alkylidenes such as metal-carbene, -vinylidene, and -allenylidene complexes have been widely used as versatile organometallic species having a double bond between a metal and a carbon. The metal-carbon double bond is reactive enough to be employed for many organic transformations catalytically as well as stoichiometrically. In fact, metathesis of alkenes via metal-carbenes may be one of the most powerful tools in recent organic synthesis, while metal-vi-nylidenes and -allenylidenes are also revealed to be the important organometallic species in various organic transformations of terminal alkynes. In sharp contrast to the rich chemistry of these carbene, vinylidene, and allenylidene complexes, the chemistry of higher cumulenylidene complexes is so far limited only to the isolation and stoichiometric reactions of metal-cumulenylidene complexes. We have now found the first example of the ruthenium-catalyzed novel reactions via metal-butatrienylidene complexes as key intermediates.