Unusual behaviour of 4,5-dichloro-1,2,3-dithiazolium chloride (Appel's salt) with 5-aminopyrazoles: a synthetic method of 1H-pyrazolo[3,4-d]thiazoles

L'abbé, G.; D'hooge, B.; Dehaen, Wim

doi:10.1039/p19950002379

Cited by 12 publications

(7 citation statements)

References 6 publications

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“…20 °C followed by stirring for 1 h was reported to give 1,3-dimethyl-1H-pyrazolo [3,4-d]thiazole-5-carbonitrile (4a) in 81% yield. 17 In our hands, however, the reaction gave a complex mixture from which we isolated five products: 4,6-dimethyl-6H-pyrazolo [3,4-c]isothiazole-3-carbonitrile (5a), N-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-1,3-dimethyl-1H-pyrazol-5-amine (3a), 5-amino-1,3-dimethyl-1Hpyrazole-4-carbothioyl cyanide (10), (3Z,3′Z)-N′,N″trisulfanediylbis (4,6-dimethyl-6H-pyrazolo[3,4-c] [3,4-c]isothiazole-3-carbimidoyl chloride (12) in 12,5,4,12,and 13% yields,respectively (Scheme 3).…”

Section: Resultsmentioning

confidence: 99%

“…12 Recently, an addition of the nucleophile, ringopening, and ring closure (ANRORC) 13 mediated ring transformation of N-(dithiazolylidene)heteroazinamines 14 vided an efficient route to heteroazine-fused thiazole-2carbonitriles. 15 Interestingly, while several N-(dithiazolylidene)heterolamines are known, 16 only one report of their transformation into fused 5−5 thiazoles exists: L'abbéet al 17 claimed the reaction of 4,5-dichloro-1,2,3-dithiazolium chloride (1) (Appel salt) 12 with 1H-pyrazol-5-amines 2 gave 1Hpyrazolo [3,4-d]thiazole-5-carbonitriles 4 via the in situ formation of the N-(dithiazolylidene)pyrazolamines 3 (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

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Reinvestigating the Reaction of 1H-Pyrazol-5-amines with 4,5-Dichloro-1,2,3-dithiazolium Chloride: A Route to Pyrazolo[3,4-c]isothiazoles and Pyrazolo[3,4-d]thiazoles

et al. 2014

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The reaction of Appel salt 1 with 1H-pyrazol-5-amines 2 gives main products N-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-1H-pyrazol-5-amines 3, and 6H-pyrazolo[3,4-c]isothiazole-3-carbonitriles 5, together with several minor side products. When the pyrazoles are N-1 methylated, the product ratio 3:5 can be modified by adjusting the pH of the reaction medium: acidic conditions favor formation of the dithiazolylidenes 3, while basic conditions favor formation of pyrazolo[3,4-c]isothiazoles 5. Furthermore, thermolysis of N-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-1H-pyrazol-5-amines 3 gives 1H-pyrazolo[3,4-d]thiazole-5-carbonitriles 4. Single crystal X-ray crystallography supports the structure of 4,6-dimethyl-6H-pyrazolo[3,4-c]isothiazole-3-carbonitrile (5a) and helps resolve a previous incorrect structural assignment of 1H-pyrazolo[3,4-d]thiazole-5-carbonitriles 4.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reinvestigating the Reaction of 1H-Pyrazol-5-amines with 4,5-Dichloro-1,2,3-dithiazolium Chloride: A Route to Pyrazolo[3,4-c]isothiazoles and Pyrazolo[3,4-d]thiazoles

et al. 2014

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“…The interaction of 5-aminopyrazoles 175 with Appel's salt (176) represents another approach to the synthesis of condensed heterocyclic systems (Scheme 61), and pyrazole derivatives of 1,2,3-dithiazole 177 and substituted pyrazolo [3,4-c]isothiazole-3-carbonitriles 178 have been observed, 124 rather than pyrazolo [3,4-d]thiazole-3-carbonitriles as previously believed. 125…”

Section: Syn Thesismentioning

confidence: 99%

Isothiazoles in the Design and Synthesis of Biologically Active Substances and Ligands for Metal Complexes

et al. 2019

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The chemistry of isothiazoles is being intensively developed, which is evidenced by the wide range of selective transformations involving the isothiazole heterocycle and the high biological activity of its derivatives that can be used as effective new drugs and plant protection chemicals. Some representatives of isothiazoles have proven to be synergists of bioactive substances, which opens the way to lower the doses of drugs used and is especially important in cancer chemotherapy. In the framework of the present review, the accomplishments in the chemistry of isothiazoles over the past 18 years are examined, whilst current strategies for the synthesis of isothiazole-containing molecules and key directions of studies in this field of heterocyclic chemistry are discussed. Considerable attention is paid to chlorinated isothiazoles and strategies for their use in the synthesis of biologically active substances. In addition, a comprehensive review of existing literature in the field of metal complexes of isothiazoles is given, including the results and prospects for the practical use of isothiazole–metal complexes as catalysts for cross-coupling reactions in aqueous and aqueous–alcoholic media (‘green chemistry’).1 Introduction2 Synthesis by Ring-Forming Reactions2.1 Intramolecular Cyclization2.2 (4+1)-Heterocyclization2.3 (3+2)-Heterocyclization2.4 Syntheses by Ring Transformations3 Isothiazoles by Ring Functionalization Reactions: Nucleophilic Substitution, Cross-Coupling and Side-Chain Functionalization4 Selected Syntheses of Biologically Active Isothiazole Derivatives5 Isothiazoles in the Synthesis of Transition-Metal Complexes and in Metal-Complex Catalysis6 Conclusion

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“…[4,5] Given this situation, we focused our attention on 1Hpyrazolo [3,4-d]thiazoles. [16][17][18] The second strategy has been reported in two cases only, namely hydrazine reacted with (5-acetylthiazol-4-yl) trifluoromethanesulfonate and arylbenzylidene-4-oxo-4,5-dihydro-1,3-thiazole derivatives, developed by Arcadi and Ammar respectively. One approach starts from judiciously substituted pyrazoles that can be used to construct the fused thiazole ring in the presence of various sulphurous reagents such as phosphorous pentasulfide, [9] thioureas, [10,11] isothiocyanate derivatives, [12][13][14] Lawesson's reagent, [15] or Appel's salt.…”

Section: Introductionmentioning

confidence: 99%

Copper‐Assisted Synthesis of Novel Pyrazolo[3,4‐d]thiazoles

et al. 2019

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Based on both the chemical and the biological importance of the pyrazole and the thiazole backbones, we report herein a convenient design of new pyrazolo[3,4-d]thiazoles for the development of molecules with a high therapeutic potential. The effective and appropriate strategy chosen consists of an intramolecular copper-catalysed N-arylation followed by the Liebeskind-Srogl cross-coupling reaction. The efficiency of copper and palladium catalysts for the first step of the synthesis was evaluated. These efforts allowed the synthesis of a variety of modulated heterobicycles.

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Unusual behaviour of 4,5-dichloro-1,2,3-dithiazolium chloride (Appel's salt) with 5-aminopyrazoles: a synthetic method of 1H-pyrazolo[3,4-d]thiazoles

Cited by 12 publications

References 6 publications

Reinvestigating the Reaction of 1H-Pyrazol-5-amines with 4,5-Dichloro-1,2,3-dithiazolium Chloride: A Route to Pyrazolo[3,4-c]isothiazoles and Pyrazolo[3,4-d]thiazoles

Reinvestigating the Reaction of 1H-Pyrazol-5-amines with 4,5-Dichloro-1,2,3-dithiazolium Chloride: A Route to Pyrazolo[3,4-c]isothiazoles and Pyrazolo[3,4-d]thiazoles

Isothiazoles in the Design and Synthesis of Biologically Active Substances and Ligands for Metal Complexes

Copper‐Assisted Synthesis of Novel Pyrazolo[3,4‐d]thiazoles

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