Benzaldehydes are indispensable building blocks in chemistry. However, the selective oxidation of toluene to benzaldehyde remains an ongoing challenge due to the low oxidation potential of benzaldehyde compared to toluene. We report herein a mild protocol that combines hydrogen atom transfer (HAT) with encapsulated air conditions and suitable catalyst loading for selective oxidation of toluene with high selectivity as well as good functional-group tolerance and a broad substrate scope for the synthesis of various high-value aromatic aldehydes. Moreover, the compatibility of this reaction with toluene derivatives of bioactive molecules further demonstrated the practicality of this approach. Mechanism studies have demonstrated that the collaboration between the oxygen quantity and the HAT catalytic system has a major impact on the high selectivity of the reaction. This study not only showcases the effectiveness of HAT strategies toward selective oxidation of toluene to benzaldehyde, but also provides an approach to controlling the selectivity of HAT reactions.

中文翻译：

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密闭空气条件下光催化选择性氧化甲苯

苯甲醛是化学中不可或缺的组成部分。然而，由于苯甲醛的氧化电位比甲苯低，因此甲苯选择性氧化为苯甲醛仍然是一个持续的挑战。我们在此报告了一种温和的方案，将氢原子转移（HAT）与封装的空气条件和合适的催化剂负载相结合，用于甲苯的选择性氧化，具有高选择性以及良好的官能团耐受性和广泛的底物范围，用于合成各种高有价值的芳香醛。此外，该反应与生物活性分子的甲苯衍生物的相容性进一步证明了该方法的实用性。机理研究表明，氧量和HAT催化体系之间的协同对反应的高选择性具有重要影响。这项研究不仅展示了 HAT 策略对甲苯选择性氧化为苯甲醛的有效性，而且提供了一种控制 HAT 反应选择性的方法。