Selectivity in Rhodium(II) Catalyzed Reactions of Diazo Compounds: Effects of Catalyst Electrophilicity, Diazo Substitution, and Substrate Substitution. From Chemoselectivity to Enantioselectivity

Abstract Rhodium catalyzed reactions of diazo compounds form a powerful set of tools for synthetic organic chemists. Reactivity modes include cyclopropanation, C-H insertion, X-H insertion, and ylide formation. A myriad of factors influences the mode of reaction, selectivity, and yield for these reaction processes. This review examines the subtle electronic, steric and conformational effects that in turn have profound impacts on reaction paths and selectivity. 1 Introduction 2 Achiral Rhodium(II) Catalysts 2.1 Effect of Catalyst Electrophilicity on Selectivity 2.2 Effect of Diazo Substitution on Selectivity 2.3 Effect of Substrate Substitution on Selectivity 3 Chiral Rhodium(II) Catalysts 3.1 Carboxylate Ligands 3.2 Carboxamidate Ligands 3.3 Phosphate Ligands 3.4 Phosphine Ligands 4 Conclusions