Photoredox‐Catalyzed Site‐Selective α‐C(sp3)−H Alkylation of Primary Amine Derivatives

By choice: Judicious choice in nitrogen protecting group allows the site‐selective functionalization α to a primary amine. Under photoredox catalysis conditions, a variety of alkene acceptors participate, leading to good yields and excellent selectivities. Tf=trifluoromethanesulfonyl.

Abstract

The synthetic utility of tertiary amines to oxidatively generate α‐amino radicals is well established, however, primary amines remain challenging because of competitive side reactions. This report describes the site‐selective α‐functionalization of primary amine derivatives through the generation of α‐amino radical intermediates. Employing visible‐light photoredox catalysis, primary sulfonamides are coupled with electron‐deficient alkenes to efficiently and mildly construct C−C bonds. Interestingly, a divergence between intermolecular hydrogen‐atom transfer (HAT) catalysis and intramolecular [1,5] HAT was observed through precise manipulation of the protecting group. This dichotomy was leveraged to achieve excellent α/δ site‐selectivity.

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