Reactions of a-imino rhodium(II) carbene complexes generated from N-Sulfonyl-1,2,3-Triazoles

Metal-stabilized carbene complexes have become increasingly important as synthetic intermediates in organic chemistry due to their unique and diverse types of reactions, e.g. cyclopropanation, C-H insertion, ylide formation, and 1,2-migration, among others. This chapter highlights the reactions of a-imino rhodium(II) carbene complexes generated from N-sulfonyl-1,2,3-triazoles. 1,2,3-Triazoles can be synthesized from terminal alkynes and azides by the 1,3-dipolar cycloaddition. In particular, 1,4-disubstituted 1,2,3-triazoles can be easily prepared in high yields and excellent regioselectivities by the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. An intermolecular O-H insertion is a well-known process in the rhodium(II)- catalyzed reactions of a-diazocarbonyl compounds. The reaction generally proceeds firstly via the formation of an ylide-type intermediate, followed by intramolecular proton transfer to the oxygen, forming an enol. a-Imino rhodium(II) carbene complexes generated from N-sulfonyl-1,2,3- triazoles could undergo an intermolecular C-H and O-H insertion as well as N-H insertion.