Photochemical Nickel-Catalyzed C–H Arylation: Synthetic Scope and Mechanistic Investigations
2016; American Chemical Society; Volume: 138; Issue: 39 Linguagem: Inglês
10.1021/jacs.6b04789
ISSN1943-2984
AutoresDrew R. Heitz, John C. Tellis, Gary A. Molander,
Tópico(s)Sulfur-Based Synthesis Techniques
ResumoAn 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.
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