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Title: Organophosphorus-catalyzed relay oxidation of H-Bpin: electrophilic C–H borylation of heteroarenes
A nontrigonal phosphorus triamide ( 1 , P{N[ o -NMe-C 6 H 4 ] 2 }) is shown to catalyze C–H borylation of electron-rich heteroarenes with pinacolborane (HBpin) in the presence of a mild chloroalkane reagent. C–H borylation proceeds for a range of electron-rich heterocycles including pyrroles, indoles, and thiophenes of varied substitution. Mechanistic studies implicate an initial P–N cooperative activation of HBpin by 1 to give P -hydrido diazaphospholene 2 , which is diverted by Atherton–Todd oxidation with chloroalkane to generate P -chloro diazaphospholene 3 . DFT calculations suggest subsequent oxidation of pinacolborane by 3 generates chloropinacolborane (ClBpin) as a transient electrophilic borylating species, consistent with observed substituent effects and regiochemical outcomes. These results illustrate the targeted diversion of established reaction pathways in organophosphorus catalysis to enable a new mode of main group-catalyzed C–H borylation.
Authors:
; ; ;
Award ID(s):
1654122 1900060
Publication Date:
NSF-PAR ID:
10219693
Journal Name:
Chemical Science
Volume:
12
Issue:
3
Page Range or eLocation-ID:
1031 to 1037
ISSN:
2041-6520
Sponsoring Org:
National Science Foundation
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