Treatment of 2-arylbenzoic acids with N-chlorosuccinimide (NCS) and NaI at 70 °C under fluorescent lighting condition gave the corresponding 3,4-benzocoumarins in good yields under transition-metal-free condition. It was found that the reactivity of NCS with NaI for the formation of 3,4-benzocoumarins from 2-arylbenzoic acids was as high as that with NIS. Thus, the formation of carboxyl radicals and their cyclization onto an aromatic ring from 2-arylbenzoic acids with much less expensive NCS and NaI, than NIS could be successfully carried out to form 3,4-benzocoumarins.

中文翻译：

---

用NCS和Na从2-芳基苯甲酸轻松制备3,4-苯并香豆素

在荧光灯照明条件下，在70°C下用N-氯代琥珀酰亚胺（NCS）和NaI处理2-芳基苯甲酸，可在无过渡金属的条件下以高收率得到相应的3,4-苯并香豆素。发现NCS与NaI从2-芳基苯甲酸形成3,4-苯并香豆素的反应性与NIS一样高。因此，可以成功地进行羧基自由基的形成并将它们从2-芳基苯甲酸环化到芳环上，该环芳烃比NIS便宜得多，而NCS和NaI比NIS便宜得多，从而可以形成3,4-苯并香豆素。