On inventing reactions for atom economy.

An important first step in making organic reactions more environmentally benign by design requires processes that are, to a first approximation, simple additions with anything else needed only catalytically. Since so few of the existing reactions are additions, synthesis of complex molecules requires the development of new atom-economic methodology. The prospect for such developments is probed in the context of ruthenium-catalyzed reactions. Using mechanistic reasoning, over 20 new processes of varying complexity have been designed and implemented. While some involved oxidation-reduction processes, most involved C-C bond-forming reactions.