The direct C–H functionalization of alcohol with -heterocycles is the most atom-economical pathway to produce hydroxyalkylated -heterocycles. However, the targeted C–H activation to enable the direct C–C coupling still remains of great challenge due to the concomitant activation of alcoholic O–H. This work puts forward a H-bonding protection for alcoholic O–H for the targeted activation of alcoholic C-H bonds. Atomic Fe-N sites anchored in graphitic carbon nitride with uncoordinated nitrogen sites has thus been proposed for this strategy, in which atomic Fe(II)-N sites are supposed to be responsible for the targeted activation of alcoholic C-H and the surface uncoordinated nitrogen to for the H-bonding with alcoholic O–H. To demonstrate the strategy, the precise modulation on the atomic Fe-N coordination in the 6-fold cavity from three heptazines have been elaborated. Atomic Fe with four N atoms from two heptazines assisted with the uncoordinated N from the free one heptazine has presented a synergistic H-bonding protection of alcoholic O–H bonds. As a result, the targeted generation and excellent stabilization of hydroxyethyl radicals have been achieved under ambient temperature. The strategy has been successfully applied for 1-propanol, 2-propanol, 1-butanol, and 1-pentanol, thus achieving efficient C–C formation in the hydroxyalkylation of varied -heterocycles.

中文翻译：

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通过 O-H 的氢键保护靶向激活醇 sp3 Cα-H，以实现 N-杂环的羟烷基化

醇与杂环的直接C-H官能化是生产羟烷基化杂环的最经济的途径。然而，由于醇类 O-H 的伴随激活，实现直接 C-C 偶联的靶向 C-H 激活仍然存在巨大挑战。这项工作提出了对醇类 O-H 的氢键保护，以靶向激活醇类 CH 键。因此，有人提出了将原子 Fe-N 位点锚定在具有不配位氮位点的石墨氮化碳中，其中原子 Fe(II)-N 位点被认为负责酒精 CH 的定向活化，而表面不配位氮则负责活化用于与醇性 O-H 形成氢键。为了演示该策略，详细阐述了三种庚嗪对 6 重腔中原子 Fe-N 配位的精确调节。具有来自两个庚嗪的四个 N 原子的原子 Fe 与来自游离的一个庚嗪的不配位 N 的辅助，呈现出醇 O-H 键的协同氢键保护。结果，在环境温度下实现了羟乙基自由基的目标生成和优异的稳定性。该策略已成功应用于1-丙醇、2-丙醇、1-丁醇和1-戊醇，从而在各种杂环的羟烷基化中实现了高效的C-C形成。