Tandem Photoredox Catalysis: Enabling Carbonylative Amidation of Aryl and Alkylhalides.

We report a new visible-light-mediated carbonylative amidation of aryl, heteroaryl, and alkyl halides. A tandem catalytic cycle of [Ir(ppy)2 (dtb-bpy)]+ generates a potent iridium photoreductant through a second catalytic cycle in the presence of DIPEA, which productively engages aryl bromides, iodides, and even chlorides as well as primary, secondary, and tertiary alkyl iodides. The versatile in situ generated catalyst is compatible with aliphatic and aromatic amines, shows high functional-group tolerance, and enables the late-stage amidation of complex natural products.

Radical Carbonylation Mediated by Continuous-Flow Visible-Light Photocatalysis: Access to 2,3-Dihydrobenzofurans.

The annulative carbonylation of alkenyl-tethered arenediazonium salts using visible-light photocatalysis in continuous flow is described. The method furnishes a diverse series of novel acetate-functionalized 2,3-dihydrobenzofurans at room temperature and moderate CO pressure (25 atm), delivering these products in a short time with straightforward scale-up. This continuous flow and free-radical approach overcomes the limitation of traditional Pd-catalyzed annulative carbonylation, giving valuable 2,3-dihydrobenzofurans in a predictable and regioselective manner.