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Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Metal- and photocatalyst-free C3-H functionalization of quinoxalin-2(1H)-ones enabled by electron donor-acceptor
An Chen1, Yating Du1, Xinchang Wang1
1College of Material, Chemistry and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Zhejiang Key Laboratory of Organosilicon Material Technology, Hangzhou Normal University, Hangzhou, 311121, P. R. China. liwanmei@hznu.edu.cn.
Abstract:
A straightforward, metal- and photocatalyst-free method for the C3-arylation and alkylation of quinoxalin-2(1H)-ones has been developed. This protocol exploits the photoactivation of electron donor-acceptor (EDA) complexes between quinoxalinones and boronic acids, facilitated by p-toluenesulfonic acid. The reaction proceeds under mild conditions (violet LED irradiation, air atmosphere) and exhibits broad substrate scope, accommodating a wide range of quinoxalinones and (hetero)aryl/alkyl boronic acids to deliver the products in moderate to excellent yields. Mechanistic studies confirm the involvement of a radical pathway and the critical role of the EDA complex. The practicality of this method is demonstrated by its scalability and successful late-stage functionalization of drug-like molecules.
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