Organic Reactions

Volume 80 in the venerable Organic Reactions series contains two chapters: the first chapter describes the use of chiral rhodium complexes to effect catalytic, asymmetric carbon-hydrogen insertion reactions intramolecularly; the second chapter describes the use of (chiral) rhodium complexes in combination with diazocarbonyl compounds, but in this case to effect a remarkable transformation that dramatically increases the molecular complexity of the substrates.The first chapter by Michael P. Doyle, Yu Liu, Maxim Ratnikov describes use of chiral rhodium complexes to effect catalytic, asymmetric carbon-hydrogen insertion reactions intramolecularly. The advent of C-H functionalization reactions as useful and predictable transformations is one of the major areas of current research in synthetic organic and organometallic chemistry. Professor Doyle and his research group have pioneered the development of specialized catalysts for effecting reactions of diazo compounds as precursors for the carbenoid intermediates responsible for the functionalization of double bonds (by cyclopropanation) and carbon hydrogen bonds (by insertion). This excellent chapter details the structural scenarios in which diazocarbonyl compounds can be generated and activated to form, inter alia, lactones, lactams and cyclic ketones.The second chapter by David M. Hodgson, Agnes H. Labande, and Sengodagounder Muthusamy also describes the use of (chiral) rhodium complexes in combination with diazocarbonyl compounds, but in this case to effect a remarkable transformation that dramatically increases the molecular complexity of the substrates. The rhodium carbenoids generated in this reaction are intercepted by carbonyl groups within the molecule (ketones, esters, amides) to form carbonyl ylides, a relatively rare class of 1,3-dipoles. These ylides are extremely reactive and combine rapidly with dipolarophiles to form oxapolycyclic products.