The Baeyer–Villiger oxidation of ketones is a crucial oxygen atom transfer (OAT) process used for ester production. Traditionally, Baeyer–Villiger oxidation is accomplished by thermally oxidizing the OAT from stoichiometric peroxides, which are often difficult to handle. Electrochemical methods hold promise for breaking the limitation of using water as the oxygen atom source. Nevertheless, existing demonstrations of electrochemical Baeyer–Villiger oxidation face the challenges of low selectivity. We report in this study a strategy to overcome this challenge. By employing a well-known water oxidation catalyst, Fe₂O₃, we achieved nearly perfect selectivity for the electrochemical Baeyer–Villiger oxidation of cyclohexanone. Mechanistic studies suggest that it is essential to produce surface hydroperoxo intermediates (M-OOH, where M represents a metal center) that promote the nucleophilic attack on ketone substrates. By confining the reactions to the catalyst surfaces, competing reactions (e.g., dehydrogenation, carboxylic acid cation rearrangements, and hydroxylation) are greatly limited, thereby offering high selectivity. The surface-initiated nature of the reaction is confirmed by kinetic studies and spectroelectrochemical characterizations. This discovery adds nucleophilic oxidation to the toolbox of electrochemical organic synthesis.

中文翻译：

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通过水中氧原子转移的高选择性电化学拜耳-维利格氧化

酮的拜尔-维利格氧化是用于酯生产的重要氧原子转移 (OAT) 过程。传统上，Baeyer-Villiger 氧化是通过热氧化化学计量过氧化物中的 OAT 来完成的，这通常很难处理。电化学方法有望打破使用水作为氧原子源的限制。然而，现有的电化学拜耳-维利格氧化演示面临着低选择性的挑战。我们在这项研究中报告了克服这一挑战的策略。通过使用众所周知的水氧化催化剂Fe ₂ O ₃，我们实现了环己酮电化学Baeyer-Villiger 氧化的近乎完美的选择性。机理研究表明，产生促进对酮底物的亲核攻击的表面氢过氧中间体（M-OOH，其中M代表金属中心）至关重要。通过将反应限制在催化剂表面，竞争反应（例如脱氢、羧酸阳离子重排和羟基化）受到极大限制，从而提供了高选择性。动力学研究和光谱电化学表征证实了反应的表面引发性质。这一发现将亲核氧化添加到电化学有机合成的工具箱中。