Access to Phenothiazine Derivatives via Iodide-Mediated Oxidative Three-Component Annulation Reaction.

Herein, a new iodide-mediated three-component annulation reaction of secondary anilines, cyclohexanones, and elemental sulfur is demonstrated, which allows access to various phenothiazines with the merits of formation of multiple chemical bonds in one single operation, high step and atom efficiency, readily available feedstocks and catalyst system, and good substrate and functional group compatibility. The developed chemistry capable of constructing novel phenothiazines with structural diversity offers a significant basis for further applications.

Reductive electrophilic C-H alkylation of quinolines by a reusable iridium nanocatalyst.

The incorporation of a coupling step into the reduction of unsaturated systems offers a desirable way for diverse synthesis of functional molecules, but it remains to date a challenge due to the difficulty in controlling the chemoselectivity. Herein, by developing a new heterogeneous iridium catalyst composed of Ir-species (Ir δ+) and N-doped SiO2/TiO2 support (Ir/N-SiO2/TiO2), we describe its application in reductive electrophilic mono and dialkylations of quinolines with various 2- or 4-functionalized aryl carbonyls or benzyl alcohols by utilizing renewable formic acid as the reductant. This catalytic transformation offers a practical platform for direct access to a vast range of alkyl THQs, proceeding with excellent step and atom-efficiency, good substrate scope and functional group tolerance, a reusable catalyst and abundantly available feedstocks, and generation of water and carbon dioxide as by-products. The work opens a door to further develop more useful organic transformations under heterogeneous reductive catalysis.

Iridium/Acid Cocatalyzed Direct Access to Fused Indoles via Transfer Hydrogenative Annulation of Quinolines and 1,2-Diketones.

Herein, we present an unprecedented iridium/acid cocatalyzed construction of fused indoles via transfer hydrogenative annulation of nonactivated quinolines and 1,2-diketones. The products are assembled via initial reduction followed by selective coupling of 1,2-diketones with the N and C8 sites of the quinolyl skeleton. The developed synthetic method features operational simplicity, readily available feedstocks, applicability for streamline synthesis of functional molecules, high step and atom efficiency, and generation of water as the byproduct.