Hydrazines dihydroxy

A recent paper by Singh et al. summarized the mechanism of the pyrazole formation via the Knorr reaction between diketones and monosubstituted hydrazines. The diketone is in equilibrium with its enolate forms 28a and 28b and NMR studies have shown the carbonyl group to react faster than its enolate forms.Computational studies were done to show that the product distribution ratio depended on the rates of dehydration of the 3,5-dihydroxy pyrazolidine intermediates of the two isomeric pathways for an unsymmetrical diketone 28. The affect of the hydrazine substituent R on the dehydration of the dihydroxy intermediates 19 and 22 was studied using semi-empirical calculations. ... 

Displacement of the 3-hydroxyl group of 74 was carried out with Et2NSF3 (DAST) (DAST - diethylaminosulfur trifluoride) in dichloromethane. The expected fluorinated product 75 on treatment with aqueous perchloric acid led to regioselective epoxide ring opening to give 76, which on treatment with hydrazine hydrate at 100 °C for 18 h yielded 3,4-dihydroxy-8-oxo-octahydropyridazino[l,6-r/][l,2,4]triazine-l-carboxylic acid phenylamide 77 (Scheme 3) <1997T9357>. 

Polyethers and polyesters having methoxybenzalazine units with various alkylene groups (C4, C6 and Cg) in the main chain were synthesized from vanillin (7,8). The condensation reaction of 4,4 -alkylenedioxybis (3-methoxybenzaldehyde) [VI] with hydrazine monohydrate was applied to the synthesis of polyethers [VII] (Mn, 7.4 x 103 for C4, 7.3 x 103 for C6 and 4.1 x 103 for Cg derivatives), as shown in Scheme 3. Polyesters [IX] (77jnh, 0.35 dl/g for C4, 0.38 dl/g for C6 and 0.43 dl/g for Cg derivatives) were synthesized from 4,4 -dihydroxy-3,3 -dimethoxybenzalazine [VIII] and di-carboxylic acid chlorides by conventional low temperature solution polycondensation, as shown in Scheme 4. 

An early report of the preparation of 4a,8a-dihydro-l,4-dihydroxy-5,8-dimethyl-pyridazino[4,5-d]pyridazine by the reaction of diethyl diacetylsuccinate with hydrazine (04CB91) was later shown to be incorrect (56JA159). The structure of this compound was shown to be 3,3 -dihydroxy-5-methyl-4,4 -bipyrazolyl. 

Topaquinone (TPQ), the oxidized form of 2,4,5-trihydroxyphenylalanine (TOPA), is the cofactor of copper-containing amine oxidases. The following model compounds have been prepared in order to understand the catalytic function of TPQ the jV-pivaloyl derivative of 6-hydroxydopamine in aqueous acetonitrile [38] topaquinone hydantoin and a series of 2-hydroxy-5-alkyl-l,4-benzoquinones in anhydrous acetonitrile (o- as well as />-quinones) [39] 2-hydroxy-5-methy 1-1,4-benzoquinone in aqueous system [40] and 2,5-dihydroxy-1,4-benzoquinone [41]. Reaction of model compounds with 3-pyrrolines revealed why copper-quinopro-tein amine oxidases cannot oxidize a secondary N [42], The studies clearly showed that certain model compounds do not require the presence of Cu for benzylamine oxidation whereas TPQ does [38,40] the aminotransferase mechanism proceeds via the -quinone form [39] the 470 nm band can be ascribed to a 71-71 transition of TPQ in />-quinonic form with the C-4 hydroxyl ionized but hydrogen bonded to some residue [40] hydrazines attack at the C-5 carbonyl, forming an adduct in the azo form [41], Electrochemical characterization has been carried out for free TPQ [43],... 

The reactions of 111 with piperidine, hydrazine hydrate and formamide ave the 3-amino derivatives 119 and 121 and the tetracyclic products 120 and 122 (81CP1101857). The 9,10-dihydroxy derivative was prepared from 45 on treatment with BBr3 in CH2C12 at 0°C for 3 h (80JHC449 81CP1101857). ... 

Hydrazin 1,2-Diethoxycarbonyl-l-(2,4-dihydroxy-phenyl)- X/2, 289 Imidazolidin l-Butyl-2-(dimethoxy-carbonyl-methylen)-4,5-dioxo-E15/2, 2238 [En— 1,1-diamin + ROOC-COOR]... 

Azin of 2,4,6-trinitro-3-hydroxy-benzaldehyde. also called 2,4,6,2, 4 ,6 -Hexanitro-3,3 -dihydroxy benzadazin (also called Azin des 2,4,6-Trinit robenzaldehyds in Ger). [H0C6H(N02)3CH N-] 2 >mw 510.28, N 21.96%, OB -53.0% in the form of bright yellow needles that are sol in ale or 50% HAc, but insol in benz. Prepd by treating1 2,4,6-Trinitro-3-hydroxybenzaldehyde in hot aq NaOH with hydrazine sulfate Refs l) Beil 8, [63] 2) H.H. Hodgson ... 

Dihydroxy-5,6-diphenylpyrazine refluxed with aqueous hydrazine hydrate gave 2-hydrazino-3-hydroxy-5,6-diphenylpyrazine, which was also obtained by heating 2-hydroxy-3-nitro-5,6-diphenylpyrazine with aqueous hydrazine (1124). Distillation of the compound claimed by Japp and Knox (317) to be 3-hydroxy-2,5-diphenylpyrazine (317, cf. 282) with zinc dust produced 2,5-diphenylpyrazine (317) reduction of the former with hydriodic acid and red phosphorus at 200 for 6 hours gave what was regarded as 2,5-diphenyl-3,4-dihydropyrazine (317). 

A solution of 2-hydroxy-3-nitro-5,6-diphenylpyrazine in dry pyridine treated dropwise with thionyl chloride gave a slightly exothermic reaction and after standing for 18 hours gave the zwitterion of 24iydroxy-5,6-diphenyl-3-pyridinio-pyrazine (12) (863) and 23-dihydroxy-5,6-diphenylpyrazine with boiling 50% aqueous hydrazine gave 2-hydrazino-3-hydroxy-5,6-diphenylpyrazine (13) (which was also prepared from 2-hydroxy-3-nitro-5,6-diphenylpyrazine) (1124). 

A dehydration of this type has actually been observed as a side reaction of a Lobry de Bruyn-Alberda van Ekenstein transformation in a very simple system. Thus, in experiments with the DL-glycerose-l,3-dihy-droxy-2-propanone isomerization in acetate, formate, and trimethylacetate buffers, pyruvaldehyde appeared in the reaction mixtures. (The formation of pyruvaldehyde from l,3-dihydroxy-2-propanone- and dl-glycerose-mineral acid mixtures had been observed much earlier.) Since these experiments in acidic buffers established that this reaction is subject to general acid and base catalysis, pyruvaldehyde must be formed in alkaline mixtures also. The results of Wohl s and Evans and Hass s experiments with DL-glycerose in alkaline solutions containing phenyl-hydrazine, in which pyruvaldehyde phenylosazone was isolated, support this view. 

This reaction has been applied to the determination of the NO (Cmin = 1 x 1CT2 /tg/ml) subsequent to its reduction by hydrazine sulfate678. Similar methods have been described for the determination of NO3 by the reaction with 2,2 -dihydroxy-4,4 -dimethoxyben-zophenone679 or 2-phenyl-1,3-benzotiazole680), of CN by the reaction with benzo-quinone and its 2,6-dichloro derivative681, of HSOJ by the reaction with N-(p-dimethy-]aminophen T)-l,4-naphthoquinoniniinc682 683). 

Disconnection of hydrazine 30a from allopurinol leaves a diamide with an extra aldehyde group 33. Disconnection of that aldehyde leaves a simple and available symmetrical heterocycle that exists in the dihydroxy tautomer 34 and will require a one-carbon electrophile corresponding to the synthon 35. We shall meet reagents for this synthon soon. 

Methyl-l H-pyrazole werden aus l,4-Dihydroxy-2-buten oder 3-Hydroxy-l-alkinen mit Hydrazin bzw. substituierten Hydrazinen in 80%iger Schwefelsaure und in Gegenwart von Iod oder Iodiden gebildet, z. B. entsteht aus 1,4-Dihydroxy-2-buten und Hydrazin 3 (5)-Methyl-1 H-pyrazol (69%)2411. 

Aryl-3,5-dihydroxy-l H-pyrazole sind in guten Ausbeuten auch aus Malonsaure und substituierten Malonsauren zuganglich, wenn sie mit l-Acetyl-2-aryl-hydrazin und Phos-phor(III)-chlorid bis zur Beendigung der ChlorwasserstofT-Entwicklung erhitzt werden (Was-serbad), z.B. ... 

Kohlensuboxid reagiert wie Malonsaure-diester mit Phenyl-hydrazin zu 3,5-Dihydroxy-1-phenyl-lH-pyrazol (Bd.Vlll4, S. 301). 

Diethoxycarbony]-3,6-dimethyl-l,4-dihydro-pyridazin reagiert mit Hydrazin-Hydrat wie 2,3-Diacetyl-bernsteinsaure-diester zu 5,5 -Dihydroxy-3,3 -dimethyl-4,4 -bi-( lH-pyrazolyl)... 

Addition of a small proportion of iron (II) sulfate to D-tartaric acid-hydrogen peroxide causes rapid conversion into a product closely related to dihydroxymaleic acid. Occurrence of a reaction with substituted hydrazines indicates the presence of a keto acid (1), and isolation of a diacetate and a dibenzoate favors the hypothesis of formation of dihydroxy-fumaric acid (2). On the basis of pH studies, Hatcher and Sturrock ... 

Opening of the oxazole ring of 7-hydroxymethyl, 7-aryloxymethyl or 7-alkoxy-methyl derivatives 44 with hydrazine hydrate on reflux in methoxyethanol produced the corresponding 7-(2,3-dihydroxy- or 2-hydroxy-3-methoxy- or 2-hydroxy-3-aryloxy-propyl)-8-hydrazinopurinediones (81KFZ59). 

The route to 4-2 outlined here is unlikely to be profitable, because oxidation of Itydrazine leads to diimide, HNNH, rather than the dihydroxy hydrazine 4-4 [49], Precursor 4-3 is appeahng because it might be possible to photochemically extrade the very stable molecule benzene from it, providing 4. However, the bicyclic precursor to 4-5 suffers from the same kind of synthetic problem as 4-4. Indeed, organic compounds with N-O bonds are uncommon, and the synthesis of 4-2 or 4-3 may require some audacity. One unorthodox approach would be the reaction of a hydrazine metal salt ( rather inaccessible species [50]) with an acyl hypohalite [51], e.g. (surprisingly, 4-6 seems to be unknown) ... 

---