FeCl3 has been identified as an earth abundant, environmentally friendly Lewis acid catalyst for ring-closing carbonyl-olefin metathesis. Lewis acid activation is used to promote the formation and fragmentation of oxetane intermediates, avoiding catalytically inactive metal-oxo species and allowing for catalytic turnover. Subsequent efforts led to the discovery of interrupted carbonyl-olefin metathesis as a divergent reaction pathway that operates via oxygen atom transfer. TfOH catalyzes the formation of uniquely substituted fluorene scaffolds from readily accessible substrates. Unlike the inert metal-oxo byproducts of previously reported approaches for carbonyl-olefin metathesis, a new ruthenium alkylidene-mediated hydrazone/oxime-olefin metathesis is developed that forms a highly reactive Ru nitride as the metal byproduct. The high reactivity of this species could be exploited to regenerate a Ru alkylidene, potentially permitting Ru-catalyzed hydrazine/oxime-olefin metathesis as a new approach for catalytic carbonyl-olefin metathesis. \r\n \r\n




Jacob Ludwig (AbbVie)