1. Carbene-catalyzed asymmetric Friedel–Crafts alkylation-annulation sequence and rapid synthesis of indole-fused polycyclic alkaloids.
- Author
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Anwar, Muhammad, Yang, Shuang, Xu, Weici, Liu, Jinggong, Perveen, Saima, Kong, Xiangwen, Zehra, Syeda Tazeen, and Fang, Xinqiang
- Subjects
ALKYLATION ,STEREOSELECTIVE reactions ,ENANTIOSELECTIVE catalysis ,ALKALOIDS - Abstract
Organocatalyzed asymmetric Friedel–Craft reactions have enabled the rapid construction of chiral molecules with highly enantioselectivity enriching the toolbox of chemists for producing complex substances. Here, we report N-heterocyclic carbene-catalyzed asymmetric indole Friedel–Crafts alkylation-annulation with α,β-unsaturated acyl azolium as the key intermediate, affording a large variety of indole-fused polycyclic alkaloids with excellent diastereo- and enantioselectivities. The reaction mechanism is also investigated, and the reaction products can be easily converted to highly functionalized indole frameworks with different core structures. Indole-fused polycyclic alkaloids are present in numerous bioactive natural products. Here an enantioselective N-heterocyclic carbene-catalysed Friedel–Crafts alkylation/annulation cascade using acyl azolium salts as the electrophile provides access to these products with high stereoselectivity. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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