Dang H, O’Callaghan HT, Wymore MM, Suarez J, Martin DBC. Selective C-H Activation of Molecular Nanodiamonds via Photoredox Catalysis.
ACS Catal 2024;
14:4093-4098. [PMID:
38510665 PMCID:
PMC10949193 DOI:
10.1021/acscatal.4c00296]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 02/22/2024] [Accepted: 02/23/2024] [Indexed: 03/22/2024]
Abstract
While substituted adamantanes have widespread use in medicinal chemistry, materials science, and ligand design, the use of diamantanes and higher diamondoids is limited to a much smaller number. Selective functionalization beyond adamantane is challenging, as the number of very similar types of C-H bonds (secondary, 2°, and tertiary, 3°) increases rapidly, and H atom transfer does not provide a general solution for site selectivity. We report a method using pyrylium photocatalysts that is effective for nanodiamond functionalization in up to 84% yield with exclusive 3° selectivity and moderate levels of regioselectivity between 3° sites. The proposed mechanism involving photooxidation, deprotonation, and radical C-C bond formation is corroborated through Stern-Volmer luminescence quenching, cyclic voltammetry, and EPR studies. Our photoredox strategy offers a versatile approach for the streamlined synthesis of diamondoid building blocks.
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