Herein, we report the first example of group transfer radical addition of O-vinylhydroxylamine derivatives onto unactivated alkenes. By utilizing O-vinylhydroxylamine derivatives as both the N- and C-donors, this reaction enables intermolecular carboamination of unactivated alkenes in an atom economical fashion. As the process is initiated through N-radical addition followed by C-transfer, linear carboamination products are afforded. This differs from canonical radical carbofunctionalization of olefins, which typically favors branched product owing to initiation by C-radical addition.
Despite remarkable recent advances in transition-metal-catalyzed C(sp3)−C cross-coupling reactions, there remain challenging bond formations. One class of such reactions include the formation of tertiary-C(sp3)−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(sp3) 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.
Through an SN2′ amination, N-alkylation and palladium-catalyzed allylic substitution sequence, we realized ipso-C–F bond arylation/alkenylation of trifluoromethylalkene derivatives.
A mild and efficient methodology involving the I2/TBHP-mediated intermolecular iodoamination of ynamides with amines for the synthesis of α-amino-β,β-diiodo-enamides was developed. This reaction provides the first intermolecular iodoamination of terminal alkynes to diiodo-enamines and can be easily applied to a wide range of substrates.
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