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Photochemical Nickel-Catalyzed C-H Arylation: Synthetic Scope and Mechanistic Investigations.

ABSTRACT: An iridium photocatalyst and visible light facilitate a room temperature, nickel-catalyzed coupling of (hetero)aryl bromides with activated α-heterosubstituted or benzylic C(sp³)-H bonds. Mechanistic investigations on this unprecedented transformation have uncovered the possibility of an unexpected mechanism hypothesized to involve a Ni-Br homolysis event from an excited-state nickel complex. The resultant bromine radical is thought to abstract weak C(sp³)-H bonds to generate reactive alkyl radicals that can be engaged in Ni-catalyzed arylation. Evidence suggests that the iridium photocatalyst facilitates nickel excitation and bromine radical generation via triplet-triplet energy transfer.

SUBMITTER: Heitz DR

PROVIDER: S-EPMC5054938 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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Photochemical Nickel-Catalyzed C-H Arylation: Synthetic Scope and Mechanistic Investigations.

Heitz Drew R DR Tellis John C JC Molander Gary A GA

Journal of the American Chemical Society 20160921 39

An iridium photocatalyst and visible light facilitate a room temperature, nickel-catalyzed coupling of (hetero)aryl bromides with activated α-heterosubstituted or benzylic C(sp<sup>3</sup>)-H bonds. Mechanistic investigations on this unprecedented transformation have uncovered the possibility of an unexpected mechanism hypothesized to involve a Ni-Br homolysis event from an excited-state nickel complex. The resultant bromine radical is thought to abstract weak C(sp<sup>3</sup>)-H bonds to genera ...[more]

PMID: 27653500

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