Unveiling Hetero‐Enyne Reactivity of Aryliminoboranes: Dearomative Hetero‐Diels–Alder‐Like Reactions
Shuang Qiu, Xin Zhang, Chaopeng Hu, Hongxu Chu, Qian‐Li Li, David A. Ruiz, Liu Leo Liu, Chen‐Ho Tung, Lingbing Kong
Abstract
Being isoelectronic with alkynes, iminoboranes with a polar B≡N triple bond have been exclusively investigated as a potent 1,2-dipole in synthetic chemistry. Herein, we disclose the unprecedented reactivity of aryliminoboranes via the BNCC π conjugation, namely hetero-enyne behavior. This allows for facile dearomative Diels-Alder-like reactions of aryliminoboranes with aldehydes. This cycloaddition features mild conditions, is catalyst-free, and has a broad substrate scope and good functional group tolerance. Kinetic and computational studies reveal its second-order reaction and concerted cyclization mechanism. This report unveils new synthetic application of iminoboranes beyond their classical reaction patterns.