- Application of Photoclick Chemistry for the Synthesis of Pyrazoles via 1,3-Dipolar Cycloaddition between Alkynes and Nitrilimines Generated In Situ
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The photochemical extrusion of gaseous nitrogen from 2,5-disubstituted tetrazoles to generate reactive nitrilimines in situ represents an efficient and attractive way to form dipoles that can be used to provide useful chemicals via 1,3-dipolar cycloadditions. The concept of “photoclick chemistry” already inspired numerous researchers, who exploited photochemical processes involving alkenes for the synthesis of adducts or the functionalization of biocompatible materials. The approach requires bioorthogonality, ease of access to the starting materials and operational simplicity. We report herein our investigations toward a photoclick reaction involving 2,5-disubstituted tetrazoles and alkynes as the dipolarophile for the synthesis of pyrazole derivatives. In addition to the numerous reports recently published on the synthesis of pyrazoles, we wish to add to the list a photochemical procedure that represents a mild and atom-economical alternative. Moreover, considering that such nitrilimines precursors can be accessed in one step from inexpensive and abundant starting materials and given the commercial availability of a broad spectrum of alkynes, we examined the scope of the photoclick reaction with respect to reactive partners, enabling the synthesis of a library of useful heteroaromatics.
- Remy, Richard,Bochet, Christian G.
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p. 316 - 328
(2018/01/27)
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- Hypervalent iodine in synthesis 87: The synthesis of 2,5-diaryl-2H- tetrazoles
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In the presence of cuprous iodide and potassium carbonate, N-arylation of 5-aryl-2H-tetrazole with a diaryliodonium salt proceeds smoothly in DMF at room temperature to give 2, 5-diaryl-2H-tetrazoles in moderate to good yield.
- Zhou, Tao,Chen, Zhen-Chu
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p. 404 - 405
(2007/10/03)
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- Palladium- and copper-catalyzed selective arylation of 5-aryltetrazoles by diaryliodonium salts
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Palladium(0)-catalyzed arylation of 5-aryltetrazoles in t-BuOH at 80°C with diaryliodonium salts proceeds in the presence of copper(II) phenylcyclopropyl carboxylate regioselectively at the N2 position.
- Beletskaya, Irina P.,Davydov, Dmitri V.,Gorovoy, Matvey S.
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p. 6221 - 6223
(2007/10/03)
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- Synthesis of Some Triazole, Tetrazole, and Tetrazine Derivatives from N-β-Naphthalenesulfonylbenzohydrazidoyl Chlorides
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A series of N-β-naphthalenesulfonylbenzohydrazidoyl chlorides 8a-d has been prepared by the action of thionyl chloride on the corresponding hydrazides 7a-d.Treatment of 8 with triethylamine and morpholine afforded the tetrazines 10 and the amidrazones 11 respectively.Acid hydrolysis of 11 yielded the hydrazides 7.Reaction of 8 with phenylhydrazine gave 3,5-diaryltetrazoles 14.However, reaction of 8 with aroylhydrazines yielded 3,5-diaryl-4-β-naphthalenesulfonylamino-4H-1,2,4-triazoles 15.The structures of the products were assigned upon the basis of their spectra, elemental analyses and alternative synthesis whereever possible.
- Hassaneen, Hamdi M.,Fahmi, Abdelgawad A.,Abdelhamid, Hyam,Yassin, Ahmady A.,Shawali, Ahmad S.
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p. 797 - 800
(2007/10/02)
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