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Not AvailableAn unmet challenge in radical relay difunctionalization of alkenes is incorporation of two discrete transient radicals in a regiocontrolled manner under transition metal-free conditions. Current protocols typically rely on persistent radicals or organometallic surrogates to trap radical adducts, thereby suppressing the undesired reactions but limiting the diversity. The direct use of two transient radicals remains synthetically elusive. We present a visible-light photoredox catalyzed alkene dialkylation strategy via a kinetically guided conjugative radical-radical coupling. This transition-metal-free approach enables two direct C(sp3)−C(sp3) bond formations across the C=C double bond using alkyl and allyl or benzyl radicals. Mechanistic investigations reveal the radical nature of the process. The success of this approach hinges on kinetically controlled radical addition to alkene substrates and the steric protection of the resulting radical adducts. This mild and functional-group tolerant reaction exhibits broad substrate scope and tolerates structurally complex substrates, highlighting its potential for late-stage functionalization. 

Abstract Carbosulfenylation of olefins represents an important class of reactions for the synthesis of structurally diverse organosulfur compounds. Previous studies typically yield 1,2‐regioselectivity. In the context of diversity‐oriented synthesis, accessing the regioreversed products is desirable, significantly broadening the scope of these reactions. In this study, we report a nickel‐catalyzed 2,1‐carbosulfenylation of trifluoromethyl‐ andgem‐difluoroalkenes, using free thiols and benzyl bromides as sulfur and carbon sources, respectively. The unusual regioselectivity observed is enabled by a “radical sorting” mechanism. The Ni catalyst activates benzyl bromide to generate a benzylic radical that undergoes hydrogen atom transfer (HAT) with the thiol to form a sulfur‐centered radical. The sulfur radical subsequently adds to the fluoroalkenes, resulting in an α‐fluoroalkyl C‐radical. This radical undergoes S_H2 with a Ni–CH₂Ar to form a C(sp³)─C(sp³) bond and quaternary center, ultimately producing valuable fluoroalkyl thioethers. Isotopic labeling experiments corroborate a hydrogen atom transfer (HAT) event within the working mechanism. 

Abstract Despite remarkable recent advances in transition-metal-catalyzed C(sp 3 )−C cross-coupling reactions, there remain challenging bond formations. One class of such reactions include the formation of tertiary -C(sp 3 )−C bonds, presumably due to unfavorable steric interactions and competing isomerizations of tertiary alkyl metal intermediates. Reported herein is a Ni-catalyzed migratory 3,3-difluoroallylation of unactivated alkyl bromides at remote tertiary centers. This approach enables the facile construction of otherwise difficult to prepare all-carbon quaternary centers. Key to the success of this transformation is an unusual remote functionalization via chain walking to the most sterically hindered tertiary C(sp 3 ) center of the substrate. Preliminary mechanistic and radical trapping studies with primary alkyl bromides suggest a unique mode of tertiary C-radical generation through chain-walking followed by Ni–C bond homolysis. This strategy is complementary to the existing coupling protocols with tert -alkyl organometallic or -alkyl halide reagents, and it enables the expedient formation of quaternary centers from easily available starting materials.