Reactions of hydrazidoyl halides: synthesis of imidazo[2,1-b]thiazole, thiazolo[2,3-c]-as-triazole and heterocyclic enaminonitriles
01 Mar 1988-Phosphorus Sulfur and Silicon and The Related Elements (Taylor & Francis Group)-Vol. 36, pp 129-133
TL;DR: Arylazo derivatives of imidazo[2,1-b]thiazoles could be obtained via reaction of hydrazidoyl halides with 2-aminothiazole as mentioned in this paper.
Abstract: Arylazo derivatives of imidazo[2,1-b]thiazoles could be obtained via reaction of hydrazidoyl halides with 2-aminothiazole. Thiazolo[2,3-c]-as-triazole and heterocyclic enaminonitriles were obtained in good yields from hydrazidoyl halides and triethylamine and from malonitrile, respectively. Pyrazolo[3,4-d]pyrimidines and pyrazolo[3,4-d]pyridazines were obtained via reaction of heterocyclic enaminonitriles with formic acid and hydrazine hydrate, respectively. The structures of the products were assigned and confirmed on the basis of their elemental analyses and spectral data.
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TL;DR: In this article, the synthesis, properties, and reactions of hydrazonoyl halides are discussed and the mechanisms of some of the reactions and the structures of some products are outlined.
Abstract: Publisher Summary Hydrazonoyl halides have emerged as an important class of intermediates, particularly for the synthesis of heterocyclic compounds. This chapter discusses the synthesis, properties, and reactions of Hydrazonoyl Halides. The mechanisms of some of the reactions and the structures of some of the products are outlined. Direct halogenation of arylhydrazone derivatives of both aliphatic and aromatic aldehydes with the appropriate halogen in glacial acetic acid is an excellent method for the synthesis of the corresponding hydrazonoyl halides. Halides are also obtained by refluxing with N- bromosuccinimide in dry carbon tetrachloride. Furthermore, bromination of aldehyde N-heteroarylhydrazones in acetic acid in the presence of sodium acetate sometimes leads to intramolecular cyclization of the initial hydrazonoyl bromides to yield the corresponding cyclized products. However, from the foregoing survey of heterocyclic hydrazonoyl halides, it appears that the main emphasis has been restricted to both their preparation and use as intermediates for further synthesis. Large areas of their chemistry, particularly regarding their physical and biological properties, remain to be developed.
58 citations
TL;DR: In this paper, a review summarizes results from the literature concerning synthesis and azo-hydrazone tautomerism of arylazo-and hetarylazo-derivatives of various bi-and tri-heterocycles reported by us and other research groups from 1981 to mid 2009.
37 citations
Cites background from "Reactions of hydrazidoyl halides: s..."
...In another report [31], it was indicated that reaction of other 2-amino-4-methylthiazole derivatives 34 with the 2oxohydrazonoyl halides 1A, B led to the formation of the respective 5-arylazoimidazo[2,1-b]thiazoles 35 (Scheme 12)....
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...[32] to yield, however, the other isomeric products 38 (Scheme 13) [31]....
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...Similar reaction of 2-aminobenzothiazole 210 with ethyl N(arylhydrazono)chloroacetate 1B afforded 212 via cyclization of the initially formed respective amidrazone (Scheme 72) [31]....
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...Imidazo[2,1-b]benzothiazoles Reactions of 2-aminobenzothiazole 210 with N-aryl 2oxopropanehydrazonoyl chloride 1A and N-aryl 2-oxo-2phenylethanehydrazonoyl bromides 1E were reported to give the respective 3-arylazoimidazo[1,2-a]benzothiazoles 211 (Scheme 72) [31]....
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TL;DR: In this article, 2-mercapto-4,5-dihydroimidazole was used to give pyrazolo[4,3-b]thiazines.
34 citations
TL;DR: In this article, aryl groups on the two different heterocyclic cores were determined by single crystal X-ray crystallography, and the key intermediates 4-aryl-2,4-diketoesters, existing as its enolic lithium salt, were synthesized in situ by a high-yield tert-BuOLi-mediated Claisen condensation of alkylphenones and diethyl oxalate.
Abstract: The treatment of α-bromoalkyl aryl ketones and 2-(propan-2-ylidene)hydrazine carbothioamide afforded 4-aryl2-(2-(propan-2-ylidene)hydrazinyl)thiazoles via a Hantzsch-thiazole synthesis, which reacted with 4-aryl-2,4-diketoesters via a sequential Knorr-pyrazole reaction to deliver a variety of aryl-substituted ethyl 1-(thiazol-2-yl)-1Hpyrazole-3-carboxylates in a one-pot fashion with moderate to high yields. The key intermediates 4-aryl-2,4-diketoesters, existing as its enolic lithium salt, were synthesized in situ by a high-yield tert-BuOLi-mediated Claisen condensation of alkylphenones and diethyl oxalate. This class of elegant molecule comprises aryl groups on the two different heterocyclic cores, and the configurations of two representative molecules were determined by single crystal X-ray crystallography.
12 citations
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TL;DR: In this article, azo coupling of dimethylphenacylsulfonium bromides with N-nitrosoacetanilides in nonaqueous solvents, and with diazotized aniline in aqueous media gave 2-bromophenylglyoxal 2-arylhydrazones (V) and the tetrazine (VI), respectively.
Abstract: The azo coupling of dimethylphenacylsulfonium bromides (I) with N-nitrosoacetanilides in nonaqueous solvents, and with diazotized aniline in aqueous media gave 2-bromophenylglyoxal 2-arylhydrazones (V) and the tetrazine (VI), respectively. V reacted with nucleophiles displacing the bromide. Treatment of V with bases gave VI via benzoylphenylnitrilimine (X). 1,3-Dipolar cycloadditions of X onto ethyl acrylate and acrylonitrile afforded the expected cycloadducts. The mechanisms of the reactions are outlined.
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