Aromatization-driven intramolecular 1,5-hydride transfer reductive amination

Abstract

Reported herein is the aromatization-driven and TfOH-promoted 1,5-intramolecular hydride transfer reductive amination for the synthesis of N-benzyl-2-(pyrrolo[1,2-a]quinoxalin-4-yl)aniline. This system is efficient and green because it is metal-free, requires no external hydrides, and reaches completion under room temperature conditions in a short time (15 min). The extraordinary reactivity is attributed to the “bifunctional reagent” 2-(4,5-dihydropyrrolo[1,2-α]quinolin-4-yl)aniline, which facilitates proton transfer during the condensation process and acts as an intrinsic hydride source to reduce the imine, and is rationalized by theoretical and experimental studies.