Ruthenium-catalyzed C-H bond arylations of indoles, thiophenes, and pyrroles were accomplished in a highly chemo- and site-selective manner through the use of removable directing groups.

Isocyanides have long proved themselves to be irreplaceable building blocks in modern organic chemistry. The unique features of the isocyano group make isocyanides particularly useful for the synthesis of a number of important classes of nitrogen heterocycles, such as pyrroles, indoles, and quinolines. Several cocyclizations of isocyanides via zwitterions and radical intermediates as well as transition-metal-catalyzed syntheses of different types of heterocycles have recently been developed. Methods starting from isocyanides often have distinct advantages over alternative approaches to the same heterocycles because of their enhanced convergence, the great simplicity of most of the operations with them, and the great variety of isocyanides readily available for use. Isocyanides have also been used in some enantioselective syntheses of chiral heterocyclic compounds, including natural products as well as precursors thereof.

Cationic ruthenium(II) complexes enabled oxidative C-H bond functionalizations with anilines bearing removable directing groups. The C-H/N-H bond cleavages occurred most efficiently in water as a sustainable solvent and provided general access to various bioactive indoles. Mechanistic studies provided strong support for a novel reaction manifold.

A cationic ruthenium(II) complex enabled efficient oxidative alkenylations of anilides in water as a green solvent and proved applicable to double C-H bond functionalizations of (hetero)aromatic amides with ample scope. Detailed studies provided strong support for a change of ruthenation mechanism in the two transformations, with an irreversible metalation as the key step in cross-dehydrogenative alkenylations of benzamides.

No abstract