Olefin metathesis has become an increasingly important catalytic process in both synthetic organic and polymer chemistry. However, the analogous catalytic processes between olefins and carbonyls has found much less success and application. The development of a mild, atom economical catalytic carbonyl olefination would represent a major advance by providing alternatives to traditional stoichiometric methodologies like the Wittig and Tebbe reactions. In this proposal, a novel ruthenium(ll) carbene catalyst system for carbonyl olefination will be developed. Research will focus on the design of a novel, highly nucleophilic ruthenium carbene and optimization of the reaction conditions to facilitate catalyst turnover. This should allow for development of both an intra- and intermolecular variant of a catalytic carbonyl olefination for aldehydes and other carbonyls that produces a minimal amount of easily removed by-products.