Open AccessC–H Alkylation via Multisite-Proton-Coupled Electron Transfer of an Aliphatic C–H Bond
Author(s) -
Carla M Morton,
Qilei Zhu,
Hunter H. Ripberger,
Ludovic TroianGautier,
Zi S. D. Toa,
Robert R. Knowles,
Erik J. Alexanian
Publication year - 2019
Publication title -
journal of the american chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.115
H-Index - 612
eISSN - 1520-5126
pISSN - 0002-7863
DOI - 10.1021/jacs.9b06834
Subject(s) - chemistry , alkylation , catalysis , radical , electron transfer , photochemistry , bond cleavage , proton coupled electron transfer , reactive intermediate , combinatorial chemistry , organic chemistry
The direct, site-selective alkylation of unactivated C(sp 3 )-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(sp 3 )-H bonds.