Carbene‐Catalyzed Activation of Remote Nitrogen Atoms of (Benz)imidazole‐Derived Aldimines for Enantioselective Synthesis of Heterocycles
作者:Xing Yang、Yongtao Xie、Jun Xu、Shichao Ren、Bivas Mondal、Liejin Zhou、Weiyi Tian、Xinglong Zhang、Lin Hao、Zhichao Jin、Yonggui Robin Chi
DOI:10.1002/anie.202016506
日期:2021.3.29
A new mode of carbene‐catalyzed heteroatom activation and asymmetric reactions is disclosed. The reaction starts with addition of a carbene catalyst to a (benz)imidazole‐derived aldimine substrate. Subsequent oxidation and proton transfer lead to the formation of a catalyst‐bound triaza‐diene as the key intermediate, in which the nitrogen atom at a site remote to the catalyst‐substrate bond is activated
The use of functionalized aldimines has been demonstrated as newly structural 1,4‐dipole precursors under carbene catalysis. More importantly, enantiodivergent organocatalysis has been successfully developed using carbene catalysts with the same absolute configuration, leading to both (R)‐ and (S)‐ enantiomers of six‐membered heterocycles with quaternary carbon centers. This strategy features a broad