58413-04-0Relevant articles and documents
An Efficient Synthesis of Substituted Pyrazoles from One-Pot Reaction of Ketones, Aldehydes, and Hydrazine Monohydrochloride
Lellek, Vit,Chen, Cheng-Yi,Yang, Wanggui,Liu, Jie,Ji, Xuebao,Faessler, Roger
supporting information, p. 1071 - 1075 (2018/02/26)
An efficient, one-pot and metal-free process for the preparation of 3,5-disubstituted and 3,4,5-trisubstituted pyrazoles on multi-gram scale was developed. One-pot condensation of ketones, aldehydes and hydrazine monohydrochloride readily formed pyrazoline intermediates under mild conditions. Oxidation of pyrazolines, in situ, employing bromine afforded a wide variety of pyrazoles. The methodology offers a fast, and often chromatography-free protocol for the synthesis of 3,4,5-substituted pyrazoles in good to excellent yields. Alternatively, a more benign oxidation protocol affords 3,5-disubstituted or 3,4,5-trisubstituted pyrazoles by simply heating pyrazolines in DMSO under oxygen.
Utility of cyano acid hydrazide in heterocyclic chemistry: A new route for the synthesis of new 1,2,4-triazolo[1,5-a]pyridines and 1,2,4-triazolo[1,5-a]isoquinolines
Hussein, Abdel Haleem Mostafa
, p. 488 - 494 (2007/10/03)
Cyano acid hydrazide 1 was condensed with cyclohexanone in refluxing ethanolic piperidine to yield the hydrazone 4. Compound 4 reacts with arylidines 5a-i to yield the 1,2,4-triazolo[1,5-a]pyridines 7a-i. Compound 4 also reacts with mixtures of aliphatic aldehydes and different active methylene reagents to yield 1,2,4-triazolo[1,5-a]pyridines 8a-d. Similarly reaction of 4 with arylazomalononitrile to yield the triazolopyridines 10a-d. Reaction of 4 with aromatic aldehydes gives 12a-e. Compound 8a reacts with elemental sulfur to yield the thieno-1,2,4-triazolopyridine 13. This underwent cycloaddition with acrylonitrile, ω-nitrostyrene, chalcone, N-phenylmalemide, dimethylacetylenedicarboxylate and tetracyanoethylene yielding the isoquinolines 15-18. All new compounds have been characterized by their IR, 1H NMR and mass spectra.