Metal‐Free Stereoconvergent C−H Borylation of Enamides

• Published in: Angewandte Chemie International Edition Vol. 62; no. 44; p. e202313205
• Main Authors: Wang, Tianhang, Wang, Zheng‐Jun, Wang, Minyan, Wu, Lei, Fang, Xiaowu, Liang, Yong, Lv, Jiahang, Shi, Zhuangzhi
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 26-10-2023
• Edition: International ed. in English
• Subjects: Additives; Boron; Catalysts; Chemical synthesis; Organic chemistry; Stereoselectivity
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202313205

Enamides, functional derivatives of enamines, play a significant role as synthetic targets. However, the stereoselective synthesis of these molecules has posed a longstanding challenge in organic chemistry, particularly for acyclic enamides that are less thermodynamically stable. In this study, we present a general strategy for constructing β‐borylenamides by C−H borylation, which provides a versatile platform for generating the stereodefined enamides. Our approach involves the utilization of metalloid borenium cation, generated through the reaction of BBr
3
and enamides in the presence of two different additives, avoiding any exogenous catalyst. Importantly, the stereoconvergent nature of this methodology allows for the use of starting materials with mixed E/Z configurations, thus highlighting the unique advantage of this chemistry. Mechanistic investigations have shed light on the pivotal roles played by the two additives, the reactive boron species, and the phenomenon of stereoconvergence.