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Photoinduced and N‑Bromosuccinimide-Mediated Cyclization of 2‑Azido‑N‑phenylacetamides

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posted on 19.02.2016, 02:21 by Zhan-Shan Li, Wei-Xia Wang, Ji-Dong Yang, Yue-Wei Wu, Wei Zhang
An efficient synthesis of quinoxalin-2(1H)-ones or spiro[cyclohexene-1,2′-imidazol]-4′-ones has been achieved in moderate to high yields by the visible light-induced and N-bromosuccinimide-mediated cyclization reaction of 2-azido-N-phenylacetamides at ambient temperature. Both the regioselectivity and the speed of cyclization are affected by the substituents attached to the phenyl ring. For example, quinoxalin-2-ones are produced as the main products when the substrates bear electron-withdrawing groups at the para-position of the phenyl ring; in contrast, spiro[cyclohexene-1,2′-imidazol]-4′-ones are obtained as the main products when the substrates bear electron-donating groups at the para-position.