Intermolecular 1,2-Difunctionalization of Nitriles via Redox Gold Catalysis: Synthesis of Benzoxazoles and
Chengzhi Xu1, Zhenyan Xu2, Yifeng Chen2
1Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University, Changzhou, 213164, P. R. China.
Abstract:
The unprecedent gold-catalyzed intermolecular 1,2-difunctionalization of nitriles with o-iodophenols or o-iodoanilines via Au(I)/Au(III) redox catalysis has been developed, providing an expedient route to the synthesis of benzoxazoles or benzimidazoles with broad substrate scope and high functional compatibility. Mechanistic investigation reveals that the Au(III)-Ar species generated via oxidative addition of o-iodophenol to MeDalphosAu+, serves as a key intermediate. Particularly, this annulation is initiated by oxidative addition, rather than the nucleophilic attack of the phenol moiety in o-iodophenol towards the nitrile. The method was also applied to the synthesis of poly aza-heterocycles via a cascade Au(I)/Au(III) and Au(I) catalysis relay.
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