Higher-order [10 + 2] cycloaddition of 2-alkylidene-1-indanones enables the dearomatization of 3-nitroindoles: access to polycyclic cyclopenta[b]indoline derivatives

Abstract

A dearomative higher-order [10 + 2] cycloaddition reaction of 3-nitroindoles and 2-alkylidene-1-indanones was developed. Using TEBA as a phase-transfer catalyst, a wide range of structurally diverse polycyclic cyclopenta[b]indoline derivatives were obtained in high yields with excellent diastereoselectivities (up to 99% yields and >20 : 1 dr) under mild conditions. This work represents the first example of the dearomatization of electron-deficient nitro-heteroarenes triggered by the higher-order [10 + 2] cycloaddition reaction.