Unsymmetrical azines via triisopropylsilylhydrazine (original) (raw)
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Novel and selective synthesis of unsymmetrical azine derivatives via a mild reaction
A new, convenient, benign procedure for the one-step synthesis of unsymmetrical azines by reaction of aromatic aldehyde derivatives and hydrazine sulfate in triethylamine and absolute ethanol solution is presented. This methodology is more useful than the well-known twostep variant (involving preparation of a hydrazone and subsequent reaction with an aldehyde), because it enables the formation of unsymmetrical azines in a one-pot and rapid method without formation of any by-product or without requirement to separate the hydrazone intermediate. The mildness, selectivity, short reaction time, easy work-up, and applicability for large-scale reactions are the main advantages of this protocol for the synthesis of unsymmetrical azine derivatives. Structures of all new compounds were elucidated by 1H and 13C NMR, IR, MS, and CHN measurements.
Addition products of hydrazine derivatives to azo-alkenes - III. α-phenylhydrazino-phenylhydrazones
Tetrahedron, 1982
The addition of phenylhydrazine to phenylazo-alkenes 4 yields ~-~nylhydrazino)-phenylhydrazones I. The reaction of phenyl~ydrazine with a-halogenated carbonyl compounds 5-affords either I or the isomeric a-(2-phenylhydrazino)-phenylhydrazones-2. Structures I ~nd 2 (>N-NH 2 and-NH-NH-groups, respectively) can be differentiated b~ IH NBR in DMSO-D6 solution. Possible pathways of the reactions leading to either I or 2 are discussed. Compounds Z are found to be precursors of phenylosazones ~.
New N-substituted hydrazones, derivatives of uridyl aldehyde
Nucleosides, Nucleotides & Nucleic Acids, 2017
N-substituted isomeric hydrazones of uridyl aldehyde have been synthesized. The occurrence of the dominant E isomers with respect to the azomethine group was confirmed by means of NMR spectroscopy. Synthesized hydrazones feature an acetonide moiety as a protection of two hydroxyl groups on the ribose part. The attempt to remove the protecting group resulted in an azohydrazone tautomeric mixture. The described compounds may be valuable chiral ligands for metal chelation. Assessment of manganese(II) ion affinity to one selected hydrazone was performed.
The Synthesis and Diazotization of Some Ketone Hydrazones
1972
Hydrazones have been synthesized in this study both from a variety of bicyclic ketones and from ketones containing either the 1-naphthyl or 2-naphthyl group. Three of these hydrazones, those derived from 1-acetonaphthone, 2-acetonaphthone, and benzosuberone, have not been reported previously in the literature. All of the hydrazones were allowed to rearrange in a diazotizing medium to produce amide products. One of these, 4,5-benzoai-heptanolactarn, has never been reported in the literature. From the results of this research, it is possible to reaffirm some general conclusions concerning the utility and scope of the hydrazone diazotization-rearrangement. Among these are the facts that the reaction generally functions well only if at least one aromatic ring is present and that it is stereospecific with migration of the group anti to the NH2 group of the original hydrazone. Thus, the assignment of hydrazone isomer configuration appears to be possible on the basis of the identity of the...
Beilstein journal of organic chemistry, 2017
Isocyanide-based multicomponent reactions (IMCRs) allow the construction of relatively complex molecules through a one-pot synthesis. The combination of IMCRs in a consecutive or sequential fashion further extends the complexity of the molecules obtained. Herein, we report the efficient application of this approach to the synthesis of acylhydrazines bearing 1,5-disubstituted tetrazoles. Our strategy was accomplished in only three steps: first, a one-pot hydrazino-Ugi-azide four-component reaction; second a hydrazinolysis and finally an additional hydrazino-Ugi-azide reaction. This sequence provides the title compounds in moderate to excellent yields. The products synthesized herein contain functional groups within their structures that can be easily modified to obtain new acylhydrazino 1,5-disubstituted tetrazoles.
Journal für Praktische Chemie/Chemiker-Zeitung, 1997
Dehydration of 2-(2-arylethyl)-2-hydroxy-4-oxopentanoic acids 1 with hydrochloric acid/acetic acid, affords 3-(2-arylethyl)-5-hydroxy-5-methyl-2(5H)-furanones 4. Compounds of type 1 and 4 represent suitable precursors for the formation of pyridazin-3-ones 7 as they smoothly react with hydrazine. A new series of s-triazolo[4,3-b]pyridazin-3-ones 12 and tetrazolo[ 1,5-b]pyridazines 15 are obtained from the 3-chloropyridazines 11 upon treatment with semicarbazide and sodium azide, respectively. Reaction of 11 with phenyl-acetyl-hydrazine provides 3-benzyl-6-phenyl-8-(2-phenyl-ethyl)s-triazolo[4,3-b]pyridazine 13 via dehydrative cyclization of the intermediate 14 which was clarified to exhibit tautomeric equilibria betweell enol-hydrazine form A and keto-hydrazine formB by means of 1H and 13C NMR spectroscopy. Attempts to synthesize 3-alloxy-pyridazines 18 by reacting 11 with sodium alloxide afford N-ally1 compounds 17.
Facile, mild and efficient synthesis of azines using phosphonic dihydrazide
Phosphorus, Sulfur, and Silicon and the Related Elements, 2019
Several bis(N'-arylpropanehydrazonoyl chlorides) were synthesized in good yields from condensation reactions of hydrazonoyl chlorides and phosphonic dihydrazide. Under the conditions employed, none of the expected phosphorylhydrazines were isolated. Nucleophilic substitution of bis(N'arylpropanehydrazonoyl chlorides) with thiophenol, sodium phenylsulfinate, hydroxyl amine, and piperidine afforded the corresponding azines. Similarly, 1,2-bis(heteroaryl)ethylidene)hydra-zines were produced from reaction of phosphonic dihydrazide and heteroaryl methyl ketones. The structures of the products were confirmed by NMR and IR spectral data along with X-ray crystal structure determination and their purities were confirmed by the elemental analyses.
The Journal of Organic Chemistry, 1991
1-Azirines 2a-b react with hydrazine in methanol to produce hexahydropyrrolo[3,2-c]pyrazol-5-ones 3a-b. The process is suggested to involve intramolecular interception of an unstable 4-aminopyrazoline intermediate resulting from C=N bond cleavage. Reaction of 2a with phenylhydrazine similarly affords 3c. In dimethyl sulfoxide, on the other hand, formamidine, guanidine, and hydrazine afford imidazole 4, pyrimidines 5a-b, amino-s-triazine 6, or triazole 9 as a consequence of C C bond cleavage in aziridine intermediate 8. The intermediacy of tautomers is proposed t o account for the diversity of products in this case.