Aromatic with hydrazine

Reactions with Amines and Amides. Hydroxybenzaldehydes undergo the normal reactions with aUphatic and aromatic primary amines to form imines and Schiff bases reaction with hydroxylamine gives an oxime, reaction with hydrazines gives hydrazones, and reactions with semicarbazide give semicarbazones. The reaction of 4-hydroxybenzaldehyde with hydroxylamine hydrochloride is a convenient method for the preparation of 4-cyanophenol (52,53). 

Miscellaneous Reactions. Aromatic sulfonic acid derivatives can be nitrated using nitric acid [52583-42-3] HNO, ia H2SO4 (19). Sultones may be treated with hydrazine derivatives to give the corresponding ring-opened sulfonic acid (20). 

Hydrazinopyridazines such as hydralazine have a venerable history as anti hypertensive agents. It is of note that this biological activity is maintained in the face of major modifications in the heterocyclic nucleus. The key intermediate keto ester in principle can be obtained by alkylation of the anion of pi peri done 44 with ethyl bromo-acetate. The cyclic acylhydrazone formed on reaction with hydrazine (46) is then oxidized to give the aromatized compound 47. The hydroxyl group is then transformed to chloro by treatment with phosphorus oxychloride (48). Displacement of halogen with hydrazine leads to the formation of endralazine (49). ... 

Aziridinium ion-based click chemistry provides convenient access to pyrazolo[l,2-ajpyrazoles, active inhibitors of penicillin-binding proteins [58, 59]. Ring-opening of aziridinium ions 32 at the benzylic position with hydrazine, followed by intramolecular cyclization, gave pyrazolidin-3-ones 37 in excellent yields (Scheme 12.27). Heating of the hydrazides 37 with aromatic aldehydes at reflux in absolute... 

The parent, unsubstituted isochromanone has been caused to react with a variety of aromatic amines to prepare Ar-substituted 1,4-dihydro-3(2.ff)-isoquinolones,4 and with amines to give amides.5 The 6,7-methylenedioxy-3-isochromanone was an intermediate in the synthesis of protopine and its allied alkaloids,6 and for the synthesis of the berberine ring system.7 The 6-methoxy analog was prepared as a potential intermediate in a camptothecin synthesis8 and 8-methoxy-4,5,6,7-tetramethyl-3-isochromanonc was an intermediate in the synthesis of sclerin.9 The compound herein described was the basis of a facile synthesis of ( l )-xylopmins,10 and its reaction with hydrazine has been reported.11... 

Regarding the series of hetero aromatic pentacyclic compounds with three heteroatoms, an accelerated synthesis of 3,5-disubstituted 4-amino-1,2,4-triazoles 66 under microwave irradiation has been reported by thermic rearrangement of dihydro-1,2,4,5 tetrazine 65 (Scheme 22). This product was obtained by reaction of aromatic nitriles with hydrazine under microwave irradiation [53]. The main limitation of the method is that exclusively symmetrically 3,5-disubstituted (aromatic) triazoles can be obtained. 

A pyridazine has found use as an antihypertensive agent. When levulinic acid is reacted with hydrazine, 153 results. This is aromatized to pyridazine 154 when reacted with bromine in acetic acid. One presumes a spontaneous dehydrobromination... 

Condensation of aromatic acyl compounds with N,N-dimethylformamide diethyl acetal in a pressure tube under the action of microwave irradiation affords easy access to l-aryl-3-dimethylaminoprop-2-enones in almost quantitative yield after 6 min. These intermediates can then be reacted with hydrazine hydrate under conventional reflux in ethanol to form the corresponding 3-substituted pyrazoles [95] (Scheme 8.69). 

Treatment of 1-chlorophthalazine 228 with alkoxide or sec-amines gave 229, whose reaction with phenacyl halides afforded 230. Cyclocondensation of the latter with hydrazine gave 231. Aromatization of 231 with tetrachlorobenzoquinone (TCBQ) gave (89FES29) the triazinophthalazine... 

Fischer1-2 decided that the mode of formation, the reactions with hydrazines, aromatic diamines, and oxidizing agents, and the reduction to D-fructose could be explained by attributing to the open-chain form of D-glucosone the a-ketoaldehyde structure L. 

Gyclocondensation of diazomalonaldehyde 336 with 4-fluoroaniline carried out in methanol-acetic acid provides l-(4-fluorophenyl)-l,2,3-triazole-l-carbaldehyde 337 in 78% yield. Oxidation with MnOz in the presence of sodium cyanide in methanol converts aldehyde 337 into methyl ester 338 with 79% yield. Hydrazide 339 (84% yield) is obtained in a reaction of ester 338 with hydrazine. Product 339 reacts with various aromatic aldehydes to give hydrazones possessing interesting antiplatelet activity (Scheme 53) <2003BMC2051>. 

The method is applied for sensitive aromatic nitro compounds, as for example for o/p-substituted nitrobenzenes. The reduction proceeds with hydrazine/precious metal (platinum) catalysts. 

The successful synthesis of 2-thienyl and substituted 2- and 3-thienyl-acetylenes in yields as high as 60-80% opened a wide variety of synthetic applications. Various addition reactions with carbonyl compounds or epoxides could be carried out with ease. Aliphatic as well as aromatic amine addition reactions, or condensation reactions with hydrazine or hydroxylamine could be easily performed. 

Lauwiner, M. Rys, P. Wissmann, J. (1998) Reduction of aromatic nitro compounds with hydrogene hydrate in the presence of an iron oxide hydroxide catalyst. I. The reduction of monosubstituted nitrobenyenes with hydrazine hydrate in the presence of ferrihydrite. 

Treatment of 176 with hydrazine hydrate then with aromatic aldehydes afforded 177 (Scheme 7) <2004BML2121> yields were not given. 

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