Metal-Free Synthesis of 4-Chloroisocoumarins by TMSCl-Catalyzed NCS-Induced Chlorinative Annulation of 2-Alkynylaryloate Esters
作者:Krissada Norseeda、Nattawadee Chaisan、Charnsak Thongsornkleeb、Jumreang Tummatorn、Somsak Ruchirawat
DOI:10.1021/acs.joc.9b02793
日期:2019.12.20
4-Chloroisocoumarins can be conveniently prepared from 2-alkynylaryloate esters via the activation of alkynes by electrophilic chlorine, generated in situ from N-chlorosuccinimide (NCS) in the presence of 10 mol % trimethylsilyl chloride (TMSCl), which leads to 6-endo-dig-selective chlorinative annulation to give the desired products in moderate to quantitative yields. The procedure employs readily
4-氯异香豆素可方便地由2-炔基芳基酸酯通过亲电氯活化炔烃而制得,该亲电基氯在10 mol%三甲基甲硅烷基氯(TMSCl)存在下由N-氯代琥珀酰亚胺(NCS)原位生成,从而生成6-内-dig-selective氯化法制环,以中等到定量的产量获得所需的产品。该方法使用了容易获得的试剂,并且可以在温和的条件下(0°C至rt)在各种底物上方便地进行。此外,该反应可扩展用于克级制备4-氯异香豆素。另外,通过分别用N-溴代琥珀酰亚胺(NBS)和N-碘代琥珀酰亚胺(NIS)代替NCS,可以以中等至良好的产率制备4-溴-和4-碘异香豆素。