Increased ring closing metathesis activity of ruthenium-based olefin metathesis catalysts coordinated with imidazolin-2-ylidene ligands

The novel air and water tolerant, imidazolinylidene-substituted ruthenium-based complex 3, has been prepared starting from RuCl2(CHPh)(PCy3)2 2 and shown to exhibit increased ring-closing metathesis activity at elevated temperature compared to that of the parent complex 2. Di-, tri-, and even tetra-substituted cycloolefins were successfully prepared from corresponding diene precursors using catalytic amounts of 3 in moderate to excellent yields.