Mild and General Access to Diverse 1H-Benzotriazoles via Diboron-Mediated N-OH Deoxygenation and Palladium-Catalyzed C-C and C-N Bond Formation.
Benzotriazoles are a highly important class of compounds with broad-ranging applications in such diverse areas as medicinal chemistry, as auxiliaries in organic synthesis, in metallurgical applications, in aircraft deicing and brake fluids, and as antifog agents in photography. Although there are numerous approaches to N-substituted benzotriazoles, the essentially one general method to N-unsubstituted benzotriazoles is via diazotization ofo-phenylenediamines, which can be limited by the availability of suitable precursors. Other methods to N-unsubstitued benzotriazoles are quite specialized. Although reduction of 1-hydroxy-1H-benzotriazoles is known the reactions are not particularly convenient or broadly applicable. This presents a limitation for easy access to and availability of diverse benzotriazoles. Herein, we demonstrate a new, broadly applicable method to diverse 1H-benzotriazoles via a mild diboron-reagent mediated deoxygenation of 1-hydroxy-1H-benzotriazoles. We have also evaluated sequential deoxygenation and Pd-mediated C-C and C-N bond formation as a one-pot process for further diversification of the benzotriazole moiety. However, results indicated that purification of the deoxygenation product prior to the Pd-mediated reaction is critical to the success of such reactions. The overall chemistry allows for facile access to a variety of new benzotriazoles. Along with the several examples presented, a discussion of the advantages of the approaches is described, as also a possible mechanism for the deoxygenation process.
Discovery Services, GVK Biosciences Pvt. Ltd. 28A, IDA Nacharam Hyderabad 500076, Andhra Pradesh, India.
Venkateshwarlu
V
Gurram
Department of Chemistry The City College and The City University of New York 160 Convent Avenue New York, NY 10031, USA.
Hari K
HK
Akula
Discovery Services, GVK Biosciences Pvt. Ltd. 28A, IDA Nacharam Hyderabad 500076, Andhra Pradesh, India.
Ramesh
R
Garlapati
Discovery Services, GVK Biosciences Pvt. Ltd. 28A, IDA Nacharam Hyderabad 500076, Andhra Pradesh, India.
Narender
N
Pottabathini
Department of Chemistry The City College and The City University of New York 160 Convent Avenue New York, NY 10031, USA.
Mahesh K
MK
Lakshman
1-hydroxy-1H-benzotriazole; benzotriazole; deoxygenation; diboron; reduction