Yuan Si-Tian, Zhou Hongwei, Zhang Lianpeng, Liu Jin-Biao, Qiu Guanyinsheng
School of Metallurgical and Chemical Engineering, Jiangxi University of Science and Technology, 86 Hongqi Road, Ganzhou 341000, China.
Org Biomol Chem. 2017 Jun 7;15(22):4867-4874. doi: 10.1039/c7ob00845g.
Bromide mediated neighboring ester-participating bromocyclizations of o-alkynylbenzoates are described here for the synthesis of benzil-o-carboxylates. 4-bromoisocoumarins are also synthesized when phenyl o-alkynylbenzoate is used as the substrate. Mechanistic studies suggest that the whole process is composed of an electrophilic bromocyclization and a dibromohydration-based ring-opening, and the neighboring ester group participates in the bromocyclization. Interestingly, the two oxygen atoms of the keto carbonyls in benzil-o-carboxylates are both derived from water. The electrophilic bromo source is in situ generated from the oxidation of bromide.
本文描述了溴化物介导的邻酯参与的邻炔基苯甲酸酯的溴环化反应，用于合成苯偶酰邻羧酸酯。当使用苯基邻炔基苯甲酸酯作为底物时，也能时，还能合成4-溴异香豆素。机理研究表明，整个过程由亲电溴环化反应和基于二溴水合作用的开环反应组成，邻酯基参与了溴环化反应。有趣的是，苯偶酰邻羧酸酯中酮羰基的两个氧原子均来自水。亲电溴源是由溴化物氧化原位生成的。
