Highly selective ethenolysis with acyclic-aminooxycarbene ruthenium catalysts

Abstract

A series of acyclic aminooxycarbene (AAOC)-ligated ruthenium metathesis catalysts was developed for the ethenolysis of methyl oleate and cis-cyclooctene. AAOC pro-ligands were conveniently synthesized via a one-pot and multigram-scale reaction, and the resulting AAOC-Ru catalysts exhibited outstanding catalytic efficiencies (turnover numbers (TONs) of 100 000 for methyl oleate and 89 000 for cis-cyclooctene) and excellent selectivities (up to 98%). The AAOC ligands possess an ambiphilic character, with both strong sigma-donors and pi-acceptors. Notably, combining the strong donating ability and the unsymmetrical structure of AAOC ligands could contribute to the enhancement of the catalytic activity and selectivity of the ruthenium catalysts. This result represents a rare example of acyclic carbene-ruthenium catalysts demonstrating high catalytic efficiency and excellent selectivity in olefin metathesis reactions.