Oxidase catalysis via aerobically generated hypervalent iodine intermediates

Abstract

The development of sustainable oxidation chemistry demands strategies to harness O as a terminal oxidant. Oxidase catalysis, in which O serves as a chemical oxidant without necessitating incorporation of oxygen into reaction products, would allow diverse substrate functionalization chemistry to be coupled to O reduction. Direct O utilization suffers from intrinsic challenges imposed by the triplet ground state of O and the disparate electron inventories of four-electron O reduction and two-electron substrate oxidation. Here, we generate hypervalent iodine reagents-a broadly useful class of selective two-electron oxidants-from O. This is achieved by intercepting reactive intermediates of aldehyde autoxidation to aerobically generate hypervalent iodine reagents for a broad array of substrate oxidation reactions. The use of aryl iodides as mediators of aerobic oxidation underpins an oxidase catalysis platform that couples substrate oxidation directly to O reduction. We anticipate that aerobically generated hypervalent iodine reagents will expand the scope of aerobic oxidation chemistry in chemical synthesis.

Radical C−H Acylation of Nitrogen Heterocycles Induced by an Aerobic Oxidation of Aldehydes

“…When this experiment was repeated in the absence of AIBN, poor result was obtained (Scheme ). It is also reported that metal additives particularly Co II and Co III promote aldehyde auto‐oxidation process . Accordingly, the reaction was performed using catalytic amount of Co‐salt, which afforded the expected product in low yield at 50 °C after 24 h (Scheme ).…”

The Hydrazine–O2 Redox Couple as a Platform for Organocatalytic Oxidation: Benzo[c]cinnoline‐Catalyzed Oxidation of Alkyl Halides to Aldehydes

“…Oxidation platforms based on organic catalysts are also of high interest, both for reasons of mechanistic diversity and because of the practical advantages that non‐metal technologies can offer . Notable examples of organocatalytic O 2 ‐coupled oxidants include quinones, flavins, nitroxyl radicals, hypervalent iodine, and perguanidinylated arenes . However, because of the difficulties inherent in the direct oxidation of organic molecules with molecular oxygen (autoxidation), many of these platforms rely on a metal co‐catalyst to facilitate the redox processes.…”

Oxidation Catalysis by an Aerobically Generated Dess–Martin Periodinane Analogue

“…[5] Contemporaneously,Miyamoto and Uchiyama et al reported iodoarene-catalyzed aerobic glycol cleavage reactions and Hofmann rearrangements under similar aldehyde-promoted aerobic oxidation conditions. [5] Contemporaneously,Miyamoto and Uchiyama et al reported iodoarene-catalyzed aerobic glycol cleavage reactions and Hofmann rearrangements under similar aldehyde-promoted aerobic oxidation conditions.…”

“…[5,21] Chelating substituents in the 2-position are frequently employed in hypervalent iodine chemistry to enhance solubility by breaking up I-O-I-O polymers that are common for iodosylbenzenes. [5,21] Chelating substituents in the 2-position are frequently employed in hypervalent iodine chemistry to enhance solubility by breaking up I-O-I-O polymers that are common for iodosylbenzenes.…”

“…To achieve reproducible aerobic oxidation chemistry,t hese investigations were carried out in the presence of CoCl 2 (1 mol %), which serves as an initiator of aldehyde autoxidation, [5,23] (Supporting Information, Figures S1 and S2). To achieve reproducible aerobic oxidation chemistry,t hese investigations were carried out in the presence of CoCl 2 (1 mol %), which serves as an initiator of aldehyde autoxidation, [5,23] (Supporting Information, Figures S1 and S2).…”