Blue light-induced 1,4-aminoalkylation of 1,3-dienes enabled by N-heterocyclic carbene-Ir(III) catalysis

Abstract

The precise alkylamination difunctionalization of 1,3-dienes represents an efficient method for synthesizing valuable allylic amines. Here, we present an efficient visible light-induced uncommon 1,4-aminoalkylation of 1-substituted 1,3-diene derivatives by developing novel N-heterocyclic carbene (NHC)-Ir(III) complex as the photocatalyst. Various allylic amines, which are difficult to obtain through other transformations so far reported, can be obtained with good to excellent yields and regio-, diastereoselectivities by using N-hydroxyphthalimide esters as both alkyl and amino precursors. The broad substrate scope and distinct 1,4-regioselectivity offer a unique supplementary approach to the established transition metal-catalyzed 3,4-aminoalkylation of 1-substituted 1,3-dienes; mechanistic studies indicate that blue light-induced allylic radical/cation crossover mediated by the photocatalyst and the π-π stacking between the phthalimidyl unit and the aryl substrates also play a crucial role in the regioselective transformation, demonstrating the superiority of this NHC-Ir(III) photocatalytic system in current cascade alkylamination transformation.