Hydrazino compounds

There are several examples of replacement of methoxy and ethoxy groups in substituted pyridazine N- oxides, with ammonia or hydrazine producing the corresponding amino and hydrazino compounds. 

Available pK data indicate that hydrazino compounds of type 224 exist predominantly as such. 

Treatment of hydrazino-compounds with iodine in chloroform can afford iodides which are convertible into methylene derivatives (7,8). An extension of this approach currently being investigated involves reduction of the hydrazones obtainable from glycopyranosiduloses and treatment of the products with iodine. 

Hydrazino compounds can react with one or two equivalents of arenediazonium ions. In reactions of arylhydrazines without substituents at the P-nitrogen in mineral acid media the initial product, the 1,4-diaryltetraz-1-ene (6.24), disproportionates rapidly into aryl azide and amine (Scheme 6-17). As shown by 15N labeling experiments (Clusius and Craubner, 1955), equal amounts of all the products shown in Scheme 6-17 are obtained. In acetate buffer the reaction is regiospecifically different. The diazonium ion attacks the a-, not the P-nitrogen, and a 1,3-diaryltetraz-l-ene is formed (6.25). 

On treatment with hydrazine or phenylhydrazine, the hydrate of l,2-0-isopropylidene-a-D-xt/lo-5-hexulofuranurono-6,3-lactone34 (74) forms122 the hydrazino compounds 75 and 76, respectively. Whereas, because of its lower nucleophilicity, phenylhydrazine does not affect... 

The ability of hydralazine and similar hydrazino compounds to reduce blood pressure was reported by Gross et al (1) in 1950. Methods of synthesis were published by Druey and Ringier (2) in 1951, along with typical reactions displayed by the compound, including several reactions which later became the bases for analysis of hydralazine and its metabolites. The drug has been widely used for treatment of hypertension, and papers on its properties and methods for its determination have been published in many languages. 

Dienophilic cyclic a-carbonylazo compounds (triazoline diones, indazolone, phthalazine dione) prepared in a flow cell, by anodic oxidation of the corresponding hydrazino compounds in acidic methanol or acetonitrile, react with dienes (Scheme 50) [72, 73]. 

Scheme 51 Anodic cycloaddition of a hydrazino compound to cyclopentadiene from ferrocene.

To investigate whether in the formation of these hydrazino compounds an Sn(ANRORC) mechanism would be involved, the reaction was studied with N-labeled hydrazine(78JHC445). If ring opening occurs, one could... 

Based on this assumption, it can easily be understood why in the case of R = t-C4H<) no incorporation of the label in the 6-hydrazino compound was found. The addition at C-3, the required initial step for incorporation in the tetrazine ring, is prevented by the strained conformation in 142 (R = t-C4H9). 

The reaction of l,4-diaryl-2-methylthiopyrimidinium iodide (39) with hydrazine did not lead to the corresponding 2-hydrazino compound, as expected, but to the rearranged l-amino-2-arylaminopyrimidinium salt (40) (90JHC1441). This transformation also occurs via an Sn(ANRORC) process, involving the open-chain intermediate 41 (Scheme III.22). It cannot... 

It was suggested that the ene hydrazino compound 132 and not the hy-drazone 129 is the active species that plays an essential role in the degenerate ring transformation. This is based on the experimental finding that compound 133 as well as compound 134 (both compounds lack a double bond between C-8 and C-9 in the ring) are not able to undergo this rearrangement reaction under the Vilsmeyer-Haak conditions (Scheme III.68). 

The reduction of nitrosamines to hydrazino compounds is accomplished by lithium aluminum hydride 5-(a-methylhydrazino)-3-phenyl-l,2,4-thiadiazole has been obtained in 65% yield by this method.170... 

Substituent exchange in the 1,2,4-triazine ring is an extensively studied reaction, as in other systems. As earlier mentioned, the introduction of a hydrogen atom into the 1,2,4-triazine ring can be achieved by oxidation of hydrazino-l,2,4-triazines (306), as was shown for 3-hydrazino and 5-hydrazino compounds. Another method is by the decarboxylation of carboxylic acids (307). This reaction was used by Paudler and Barton for the preparation of the parent 1,2,4-triazine (1) by decarboxylation of the 3-carboxylic acid (66JOC1720), but decarboxylation of 5- and 6-carboxylic acids are also well-documented reactions. 

Prepared by diazotisation of the corresponding amino-hydrazino-compound, this material... 

The reaction of 1,2,4-triazino[5,6-/>]indole-3-thione (93a X= SH) with tetracyanoethylene affords, as one of three products, the thiazolotriazinoindole (94). The 3-hydrazino compound (93b X= NHNH,) gives the triazolotriazinoindole (95) and triazepinotriazinoindole (96) [94T9997],... 

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