Samanta Ramesh C, Yamamoto Hisashi
Molecular Catalyst Research Center, Chubu University, 1200 Matsumoto, Kasugai, Aichi 487-8501 (Japan).
Chemistry. 2015 Aug 17;21(34):11976-9. doi: 10.1002/chem.201502234. Epub 2015 Jul 16.
Electrophilic halogenation is used to produce a wide variety of halogenated compounds. Previously reported methods have been developed mainly using a reagent-based approach. Unfortunately, a suitable "catalytic" process for halogen transfer reactions has yet to be achieved. In this study, arylamines have been found to generate an N-halo arylamine intermediate, which acts as a highly reactive but selective catalytic electrophilic halogen source. A wide variety of heteroaromatic and aromatic compounds are halogenated using commercially available N-halosuccinimides, for example, NCS, NBS, and NIS, with good to excellent yields and with very high selectivity. In the case of unactivated double bonds, allylic chlorides are obtained under chlorination conditions, whereas bromocyclization occurs for polyolefin. The reactivity of the catalyst can be tuned by varying the electronic properties of the arene moiety of catalyst.
亲电卤化反应用于制备多种卤代化合物。先前报道的方法主要是基于试剂的方法。遗憾的是，尚未实现适用于卤素转移反应的“催化”过程。在本研究中，发现芳胺可生成N-卤代芳胺中间体，该中间体作为高活性但具有选择性的催化亲电卤素源。使用市售的N-卤代琥珀酰亚胺（例如NCS、NBS和NIS）可对多种杂芳族和芳族化合物进行卤化，产率良好至优异，且选择性非常高。在未活化双键的情况下，氯化条件下可得到烯丙基氯，而对于聚烯烃则发生溴环化反应。通过改变催化剂芳烃部分的电子性质可以调节催化剂的反应活性。
