- Selective Synthesis of N-H and N-Aryl Benzotriazoles by the [3 + 2] Annulation of Sodium Azide with Arynes
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The synthetic utility of NaN3 as the azide component in the [3 + 2] annulation with arynes generated from 2-(trimethylsilyl)aryltriflates resulting in the transition-metal-free synthesis of N-H and N-aryl benzotriazoles has been demonstrated. Using CsF as the fluoride source in CH3CN, the N-H benzotriazoles are formed in high selectivity instead of the expected azidobenzene. Interestingly, N-aryl benzotriazoles are formed using KF and THF as solvent in an open-flask reaction. Moreover, a method for the N1-arylation of benzotriazole is also presented.
- Guin, Avishek,Gaykar, Rahul N.,Bhattacharjee, Subrata,Biju, Akkattu T.
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p. 12692 - 12699
(2019/10/11)
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- Making endo-cyclizations favorable again: A conceptually new synthetic approach to benzotriazoles via azide group directed lithiation/cyclization of 2-azidoaryl bromides
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Although benzotriazoles are important and ubiquitous, currently there is only one conceptual approach to their synthesis: bridging the two ortho-amino groups with an electrophilic nitrogen atom. Herein, we disclose a new practical alternative-the endo-cyclization of 2-azidoaryl lithiums obtained in situ from 2-azido-aryl bromides. The scope of the reaction is illustrated using twenty-four examples with a variety of alkyl, alkoxy, perfluoroalkyl, and halogen substituents. We found that the directing effect of the azide group allows selective metal-halogen exchange in aryl azides containing several bromine atoms. Furthermore, (2-bromophenyl)diazomethane undergoes similar cyclization to give an indazole. Thus, cyclizations of aryl lithiums containing an ortho-X = Y = Z group emerge as a new general approach for the synthesis of aromatic heterocycles. DFT computations suggested that the observed endo-selectivity applies to the anionic cyclizations of other functionalities that undergo "1,1-additions" (i.e., azides, diazo compounds, and isonitriles). In contrast, cyclizations with the heteroatomic functionalities that follow the "1,2-addition" pattern (cyanates, thiocyanates, isocyanates, isothiocyanates, and nitriles) prefer the exo-cyclization path. Hence, such reactions expand the current understanding of stereoelectronic factors in anionic cyclizations.
- Ageshina, Alexandra A.,Chesnokov, Gleb A.,Topchiy, Maxim A.,Alabugin, Igor V.,Nechaev, Mikhail S.,Asachenko, Andrey F.
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p. 4523 - 4534
(2019/05/17)
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- Compounds and methods
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Compounds of this invention are non-peptide, reversible inhibitors of type 2 methionine aminopeptidase, useful in treating conditions mediated by angiogenesis, such as cancer, haemangioma, proliferative retinophathy, rheumatoid arthritis, atherosclerotic
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