Amidyl Radical Directed Remote Allylation of Unactivated sp³ C−H Bonds by Organic Photoredox Catalysis

Abstract

The development of visible‐light‐mediated allylation of unactivated sp3 C−H bonds is reported. The remote allylation was directed by the amidyl radical, which was generated by photocatalytic fragmentation of a pre‐functionalized amide precursor. Both aromatic and aliphatic amide derivatives could successfully deliver the remote C−H allylation products in good yields. A variety of electron deficient allyl sulfone systems could be used as δ‐carbon radical acceptor.

Transition-metal-catalyzed C–H allylation reactions

“…Recently, visible-light-mediated photoredox catalysis has emerged as a powerful tool to access various organic frameworks under mild conditions. Generation of radical intermediate, [119][120][121][122][123] however, limits the stereoselectivity of any protocol due to multiple by-product formation. Unarguably, dual catalysis combining photocatalysts with TM catalyst outshines single-metal-catalyzed protocols 124,125 in terms of delineating new chemical transformations.…”

Remote Allylation of Unactivated C(sp3)–H Bonds Triggered by Photogenerated Amidyl Radicals

“…Flechsig and Wang recently reported an allylation of C(sp 3 )−H bonds with allyl sulfones activated by electronwithdrawing groups via photocatalytic fragmentation of prefunctionalized aryloxy amides (Scheme 1C). 9 Herein, we report a direct allylation of unactivated C(sp 3 )−H bonds in unfunctionalized amides with simple allylic chlorides (Scheme 1D). By applying a 1,5-HAT process triggered by photoredoxgenerated amidyls, various allyl-substituted amides are obtained with good yields, high δ-selectivity, and high functional group tolerance.…”

Electrophilic Aminating Agents in Total Synthesis

“…Amidyl radicals have found extensive use in synthesis due to their high reactivity,f unctional group tolerance and profoundly electrophilic character. [248,[257][258][259][260][261][262] However,t heir high reactivity presents challenges because competitive intramolecular H-atom abstraction reactions can often occur in preference to the target CÀNb ond formation. [256,263] Despite this,a midyl radicals provide ap opular platform for the synthesis of polyheterocycles.U ntil recently,a midyl radicals were typically prepared by homolysis of an NÀOo rNhalogen bond under harsh reaction conditions.H owever, there are now anumber of milder photocatalytic methods for this transformation.…”