C–H Alkylation via Multisite-Proton-Coupled Electron Transfer of an Aliphatic C–H Bond

The direct, site-selective alkylation of unactivated C­(sp3)–H bonds in organic substrates is a long-standing goal in synthetic chemistry. General approaches to the activation of strong C–H bonds include radical-mediated processes involving highly reactive intermediates, such as heteroatom-centered...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2019-08, Vol.141 (33), p.13253-13260
Main Authors: Morton, Carla M, Zhu, Qilei, Ripberger, Hunter, Troian-Gautier, Ludovic, Toa, Zi S. D, Knowles, Robert R, Alexanian, Erik J
Format: Article
Language:English
Subjects:
Chemistry
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Summary:The direct, site-selective alkylation of unactivated C­(sp3)–H bonds in organic substrates is a long-standing goal in synthetic chemistry. General approaches to the activation of strong C–H bonds include radical-mediated processes involving highly reactive intermediates, such as heteroatom-centered radicals. Herein, we describe a catalytic, intermolecular C–H alkylation that circumvents such reactive species via a new elementary step for C–H cleavage involving multisite-proton-coupled electron transfer (multisite-PCET). Mechanistic studies indicate that the reaction is catalyzed by a noncovalent complex formed between an iridium­(III) photocatalyst and a monobasic phosphate base. The C–H alkylation proceeds efficiently using diverse hydrocarbons and complex molecules as the limiting reagent and represents a new approach to the catalytic functionalization of unactivated C­(sp3)–H bonds.
ISSN:0002-7863
1520-5126
DOI:10.1021/jacs.9b06834