C–H Amination Enabled [2+1+1+1] Annulation Reaction in Water: Access to Benzoxazoles. Issue 44 (13th October 2021)

• Record Type: Journal Article
• Authors: Chen, Fulin; Zhu, Chuanle; Yang, Zhiyi; Liu, Chi; Zeng, Hao; Wu, Wanqing; Jiang, Huanfeng
• Is Part Of: European journal of organic chemistry. Issue 44(2021)
• Page Start: 5998
• Page End: 6001
• Publication Date: 2021-10-13
• Subjects: Amination -- Annulation -- Benzoxazoles -- Heterocycles -- Synthetic methods; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.202100942
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: A novel and efficient four‐component reaction in water is reported, enabling the efficient synthesis of benzoxazoles from aldehydes, benzo‐1, 2‐quinones, hydroxylamine hydrochloride, and water via a C−H amination strategy. Importantly, water is not only employed as the solvent but also used as the oxygen source of the benzoxazole skeletons, while inorganic hydroxylamine hydrochloride serves as the nitrogen source. Preliminary mechanistic studies prove that the aldoxime rather than the quinone oxime is the reaction intermediate. Abstract : A novel and efficient strategy to prepare benzoxazoles through a [2+1+1+1] annulation of benzo‐1, 2‐quinones, aldehydes, hydroxylamine hydrochloride and water is reported. The method is operationally simple and gram‐scalable; it has a broad substrate scope and valuable functional group tolerance, and ensures high yields.