Ruthenium Carbenes

Alkene metathesis with ruthenium carbenes has become one of the most widely used synthetic methods employing a transition metal catalyst. This chapter focuses on the chemistry of ruthenium carbenes. It provides a mechanistic background and details of recent advances in mechanistic understanding. The chapter then discusses the identification of ruthenacyclobutane intermediates and conformational changes of the ruthenium carbene, derived from early Density Functional Theory (DFT) calculations and confirmed through experiment. Next, the chapter focuses on the development of phosphine-free ruthenium carbene complexes and ruthenium carbene decomposition pathways. This is followed by a discussion on issues of selectivity in alkene metathesis. Finally, the applications are overviewed in three subsections: natural product synthesis, applications in aqueous media, and the use of metathesis as a means for creating diverse nonnatural structures.