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  • Investigations into mechanism and origin of regioselectivity in the metallaphotoredox-catalyzed α-arylation of N -alkylbenzamides
Title: Investigations into mechanism and origin of regioselectivity in the metallaphotoredox-catalyzed α-arylation of N -alkylbenzamides
A mechanistic study on the α-arylation of N -alkylbenzamides catalyzed by a dual nickel/photoredox system using aryl bromides is reported herein. This study elucidates the origins of site-selectivity of the transformation, which is controlled by the generation of a hydrogen atom transfer (HAT) agent by a photocatalyst and bromide ions in solution. Tetrabutylammonium bromide was identified as a crucial additive and source of a potent HAT agent, which led to increases in yields and a lowering of the stoichiometries of the aryl bromide coupling partner. NMR titration experiments and Stern–Volmer quenching studies provide evidence for complexation to and oxidation of bromide by the photocatalyst, while elementary steps involving deprotonation of the N -alkylbenzamide or 1,5-HAT were ruled out through mechanistic probes and kinetic isotope effect analysis. This study serves as a valuable tool to better understand the α-arylation of N -alkylbenzamides, and has broader implications in halide-mediated C–H functionalization reactions.  more » « less
Award ID(s):
1700982
PAR ID:
10439825
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Chemical Science
Volume:
13
Issue:
35
ISSN:
2041-6520
Page Range / eLocation ID:
10566 to 10573
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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