Difunctionalization of Cyclopropylanilines and Cyclobutylanilines

Abstract

We have previously developed photoredox conditions for ring opening of cyclopropylanilines and cyclobutylanilines. Distonic radical cations are presumably the intermediates. Although commonly producing in gas phase such as in the ionization chamber of a mass spectrometer, in solution phase, the methods for generating them are quite limited. Bearing a spatially separated radical and cation within the same molecule, these species possess bimodal reactivities that are distinct from those of radicals, ions, or classical radical ions (the radical and the ion reside at the same atom). In the [3+2] annulation of cyclopropylanilines and the [4+2] annulation of cyclobutylanilines developed by us, only one pi bond of alkenes, alkynes, dienes, enynes, or diynes reacts with the radical and the cation moiety of the distonic radical cations sequentially to form a five-membered and six-membered carbocycle respectively. Therefore, the two reactions don’t maximize the distonic radical cations’ bimodal reactivity. We have recently focused on identifying a suitable nucleophile and a radical acceptor to orthogonally intercept the cation and the radical moiety, which allows us to capitalize the distonic radical cations’ bimodal reactivity fully. Herein, we report our efforts in harvesting the distonic radical cations' bimodal reactivity, which results in 1,3-difunctionalization of cyclopropylanilines and 1,4-difunctionalization of cyclobutylanilines.