Synthesis of Homoallylic Amines by Radical Allylation of Imines with Butadiene under Photoredox Catalysis

Abstract

Ionic (2 e−) nucleophilic addition of allylmetal regents to imines dominates the synthesis of homo‐allyl amine; however, single electron (1 e−) mediated imine allylation with feedstocks butadiene as an alternative allyl source remains unexplored. In this work, we report a conceptually different radical–radical cross‐coupling strategy for the synthesis of a homoallyl amine between an α‐amino alkyl radical and a transient allylic radical. This metal‐free method provided a novel approach for the synthesis of homoallylic amines (>80 examples) from readily available materials with excellent regioselectivity and exceptional broad functional group compatibility.

Visible light-mediated NHC and photoredox co-catalyzed 1,2-sulfonylacylation of allenesviaacyl and allyl radical cross-coupling

“…Early in 1951, Borcherdt's group established the Ni-catalyzed homo-coupling 4 of allyl radicals to access 1,5-diene. However, radical–radical cross-couplings involving allyl radicals 5–8 have been developed slowly. Since the radical–radical coupling proceeds via a diffusion-controlled manner, 3 selectivity modulation is an obstacle.…”

“…Very recently, Shi and coworkers developed an elegant radical difunctionalization of dienes based on allyl and α-aza-benzyl radical cross-couplings. 8 Despite these innovative approaches (Scheme 1a), the variety of coupling partners was limited to aryl 5 or benzyl 6–8 radical analogs, and the development of novel carbon-centered radical coupling sources is a highly appealing but challenging task in allyl radical chemistry.…”