Iron Catalyzed Dual-Oxidative Dehydrogenative (DOD) Tandem Annulation of Glycine Derivatives with Tetrahydrofurans

A novel iron-catalyzed dual-oxidative dehydrogenative (DOD) tandem annulation of glycine derivatives with tetrahydrofurans (THFs) for the synthesis of high value quinoline fused lactones has been developed. The reactions were performed under mild reaction conditions. And the use of cheap substrates (glycine derivatives and THF) and an even cheaper simple inorganic iron salt as the catalyst makes this protocol very attractive for potential synthetic applications

CBr₄ Mediated Oxidative C–N Bond Formation: Applied in the Synthesis of Imidazo­[1,2-α]pyridines and Imidazo­[1,2-α]pyrimidines

The carbon tetrabromide mediated oxidative carbon–nitrogen bond formation of 2-aminopyridines or 2-aminopyrimidines with β-keto esters or 1,3-diones, leading to a variety of complex imidazo­[1,2-α]­pyridines or imidazo­[1,2-α]­pyrimidines, is reported. The reactions were realized under mild and metal-free conditions

Co(II)-Catalyzed Regioselective Cross-Dehydrogenative Coupling of Aryl C–H Bonds with Carboxylic Acids

A cobalt­(II)-catalyzed regioselective aryl C–H bond oxygenation between arenes and aryl or aliphatic carboxylic acids under bidendate-chelation assistance is developed. This method provides an efficient approach to acyoxy-substituted arenes with a broad range of functional group tolerance. Furthermore, this reaction system could be further applied to the preparation of polyfunctional naphthylenes

Aerobic Oxidative Mannich Reaction Promoted by Catalytic Amounts of Stable Radical Cation Salt

A catalytic amount of triarylaminium salt is demonstrated to be an efficient initiator for oxidative Mannich reaction of tertiary amines and nonactivated ketones under mild neutral conditions. Air is essential for this reaction and acts as a terminal oxidant. Metal catalysts, acid or base additives, and stoichiometric amounts of chemical oxidants are all avoided in this methodology. Six examples of intramolecular cyclized products are also delivered

Co(II)-Catalyzed Regioselective Cross-Dehydrogenative Coupling of Aryl C–H Bonds with Carboxylic Acids

A cobalt­(II)-catalyzed regioselective aryl C–H bond oxygenation between arenes and aryl or aliphatic carboxylic acids under bidendate-chelation assistance is developed. This method provides an efficient approach to acyoxy-substituted arenes with a broad range of functional group tolerance. Furthermore, this reaction system could be further applied to the preparation of polyfunctional naphthylenes

Co(III)-Catalyzed Coupling-Cyclization of Aryl C–H Bonds with α‑Diazoketones Involving Wolff Rearrangement

An unusual cobalt­(III)-catalyzed cross-coupling/cyclization of aryl C–H bonds of <i>N</i>-nitrosoanilines with α-diazo-β-ketoesters has been achieved. This protocol features a unique combination of Csp²-H activation/Wolff rearrangement process, allowing for the rapid assembly of quaternary 2-oxindoles. The empirical evidence and density functional theory (DFT) calculations reveal the trapping process of transient acceptor ketene intermediates by cobalt metallocycles