Catalytic N-alkylation is a frequently employed method to synthesize secondary amines and imines, yet selectivity control remains as a challenge that normally requires specialized catalysts under harsh reaction conditions. Here we propose a light-switchable N-alkylation of amines with aromatic halides for selective synthesis of secondary amines and imines, using an amine-functionalized metal-organic framework (MIL-125-NH) under mild conditions. The MIL-125-NH catalyst possesses Lewis acidic sites, which catalyze direct dehalogenative condensation of bromides with primary amines to produce secondary amines in the dark. Upon irradiation, the MIL-125-NH reduces molecular oxygen to create oxygen radicals, converting bromides into the corresponding aldehydes to yield imines a dehydrative coupling with amines. With appropriate acidity, rapid oxygen reduction kinetics, and optimized adsorption of aromatic bromides and generated water, the system catalyzes the conversion of a wide range of substrates, thus featuring it a promising method for applications.

中文翻译：

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使用胺官能化 MOF 进行光开关 N-烷基化

催化 N-烷基化是合成仲胺和亚胺的常用方法，但选择性控制仍然是一个挑战，通常需要在恶劣的反应条件下使用专门的催化剂。在这里，我们提出了在温和条件下使用胺官能化金属有机框架（MIL-125-NH），用芳香族卤化物对胺进行光可切换的N-烷基化，以选择性合成仲胺和亚胺。 MIL-125-NH催化剂具有路易斯酸性位点，可催化溴化物与伯胺在暗处直接脱卤缩合生成仲胺。辐射后，MIL-125-NH 会还原分子氧，产生氧自由基，将溴化物转化为相应的醛，产生亚胺，与胺发生脱水偶联。该系统具有适当的酸度、快速的氧还原动力学以及对芳香族溴化物和生成水的优化吸附，可催化多种底物的转化，因此是一种有前景的应用方法。