Conventional acid catalysis for Markovnikov selective hydroamination of alkenes using anilines suffered from limitations on substrate scope and low regioselectivity attributed to buffering effect of anilines and competing Friedel-Crafts alkylation, respectively. Herein we demonstrate Markovnikov hydroamination of aliphatic alkenes using anilines through light-driven triple catalysis consisting of cobalt, photoredox, and weak Brønsted acid catalysts under blue LED irradiation. Our protocol enables to generate an alkyl cobalt(IV) species from aliphatic alkenes under weak acidic conditions, expanding the accessible N-alkylanilines and N,N-dialkylanilines. Since the alkyl cobalt(IV) species reacts with anilines through S_N2 manner unlike a free carbocation, Friedel-Crafts alkylation is completely suppressed. When Brønsted acid catalyst is replaced with Lewis base/acid pair catalysts, the quadruple catalytic system is amenable to N-alkylation of azoles.
DOI: 10.1093/bulcsj/uoag021