The Disappearing Director: The Case of Directed N‐Arylation via a Removable Hydroxyl Group

A facile and broadly applicable method for the regiospecific N‐arylation of benzotriazoles is reported. Copper‐mediated reactions of diverse 1‐hydroxy‐1H‐benzotriazoles with aryl boronic acids lead to 1‐aryl‐1H‐benzotriazole 3‐oxides. A N1‐OH→N3 prototropy in the 1‐hydroxy‐1H‐benzotriazoles is plaus...

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Published in:Advanced synthesis & catalysis 2018-07, Vol.360 (13), p.2503-2510
Main Authors: Andrzejewska, Magdalena R., Vuram, Prasanna K., Pottabathini, Narender, Gurram, Venkateshwarlu, Relangi, Siva Subrahmanyam, Korvinson, Kirill A., Doddipalla, Raju, Stahl, Lothar, Neary, Michelle C., Pradhan, Padmanava, Sharma, Somesh, Lakshman, Mahesh K.
Format: Article
Language:English
Subjects:
Aromatic compounds
arylation
Benzotriazole
benzotriazoles
boronic acid
Chemical reduction
copper
directing group
Hydroxyl groups
Oxides
Reagents
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Summary:A facile and broadly applicable method for the regiospecific N‐arylation of benzotriazoles is reported. Copper‐mediated reactions of diverse 1‐hydroxy‐1H‐benzotriazoles with aryl boronic acids lead to 1‐aryl‐1H‐benzotriazole 3‐oxides. A N1‐OH→N3 prototropy in the 1‐hydroxy‐1H‐benzotriazoles is plausibly the underlying basis, where the tautomer is captured by the boronic acid, leading to C−N (not C−O) bond formation. Because the N−O bond in amine N‐oxides and 1‐hydroxy‐1H‐benzotriazoles can be easily reduced by diboron reagents such as (pinB)2 and B2(OH)4, exposure of the 1‐aryl‐1H‐benzotriazole 3‐oxides to B2(OH)4 then leads to facile reduction of the N−O bond resulting in diverse, regiospecifically‐arylated benzotriazoles. Thus, the N‐hydroxyl group in 1‐hydroxy‐1H‐benzotriazoles acts as a disposable arylation director.
ISSN:1615-4150
1615-4169
DOI:10.1002/adsc.201701611