中国科学院化学研究所叶松团队开发了一种通过N-杂通过环卡宾催化芳烃合成对映选择性合成轴向手性苯并噻吩/苯并呋喃稠合二芳基的方法。相关研究成果发表在2021年4月14日出版的《德国应用化学》。

轴向手性二芳基支架广泛应用于天然产物、手性配体和有机催化剂中。然而，NHC催化芳香环的从头构建以及伴随的轴向手性诱导用于合成二芳基阿托品单体的研究还远远不够，并且在NHC催化下有效合成四邻位取代的轴向手性二芳基仍然是一个尚未解决的问题。

该文中，研究人员报道了一种NHC催化的从头合成轴向手性苯并噻吩/苯并呋喃稠合双芳基的方法，该方法通过[2+4]环化、脱羧和氧化芳构化以及中心-轴向手性转化的级联策略，从烯醛和2-苄基-苯并噻吩/苯并呋喃-3-甲醛合成轴向手性苯并噻吩/苯并呋喃稠合双芳基。

所开发的方法提供了一种获得具有高对映选择性的新型轴向手性苯并噻吩/苯并呋喃稠合二芳基，并适用于四邻位取代二芳基合成的高效和通用的途径。

附：英文原文

Title: Enantioselective Synthesis of Axially Chiral Benzothiophene/Benzofuran‐Fused Biaryls via N‐Heterocyclic Carbene Catalyzed Arene Formation

Author: Chun-Lin Zhang, Yuan-Yuan Gao, Hai-Ying Wang, Bang-An Zhou, Song Ye

Issue&Volume: 2021-04-14

Abstract: Axially chiral biaryl scaffolds are prevalent in natural products, chiral ligands, and organocatalysts. However, NHC‐catalyzed de novo  construction of aromatic ring with concomitant axially chiral induction for the synthesis of biaryl atropisomers is far less developed, and the efficient synthesis of axially chiral tetra‐ ortho  ‐substituted biaryls remains an unsolved problem under NHC catalysis.  Herein, we report an NHC‐catalyzed de novo  synthesis of axially chiral benzothiophene/benzofuran‐fused biaryls  from enals and 2‐benzyl‐benzothiophene/benzofuran‐3‐carbaldehydes through a cascade strategy of [2+4] annulation, decarboxylation, and oxidative aromatization with central‐to‐axial chirality conversion. The developed method provides an efficient and general access to novel axially chiral benzothiophene/benzofuran‐fused biaryls in high enantioselectivities and works well for the synthesis of tetra‐ ortho  ‐substituted biaryls.

DOI: 10.1002/anie.202103415

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202103415