Dearomative tandem annulation to access chiral indoline-fused bicyclo[2.2.2]octanes using modularly designed organocatalysts†
Qing-Zhu Li,Xin-Xin Kou,Rong-Sheng Tong,Jun-Long Li
Organic Chemistry Frontiers Pub Date : 01/16/2023 00:00:00 , DOI:10.1039/D2QO01859D
Abstract

Herein, we describe an asymmetric dearomative tandem annulation between 3-nitroindoles and 7-oxo-5-heptenals. The cascade reactions proceeded smoothly using modularly designed organocatalysts self-assembled from cinchona-squaramide and D-proline. As a result, a collection of enantioenriched indoline-fused bicyclo[2.2.2]octanes featuring six vicinal stereocenters were smoothly obtained in good yields with excellent enantioselectivities (up to >99% ee). This protocol provides an economical and practical approach for the asymmetric synthesis of structurally complex indolines.

Graphical abstract: Dearomative tandem annulation to access chiral indoline-fused bicyclo[2.2.2]octanes using modularly designed organocatalysts