3-Nitrophenyl hydrazones

For example, heating 3-nitrophenyl hydrazone of propioaldehyde 187 in a mixture of toluene - 85% orthophosphoric acid gave rise to a hardly separable mixture of two regioisomers 188 and 189 (Scheme 93) in 70% overall yield [142]. 

Scheme 95 The Fischer cyclization of ethyl pyruvate 3-nitrophenyl hydrazone...

Nitrophenyl hydrazones of ketones reacted similarly. On heating aryUiydrazones of pyruvic ester 192 with polyphosphoric acid (PPA), mixtures of ethyl 4- and 6-nitroindole-2-carboxylates were formed [145, 146] (Scheme 95). 

For the preparation of oximes, pheuylhydrazones and p nitrophenyl-hydrazones (where applicable), see under Aromatic Aldehydes, Section IV,135,4-d. 

Alternatively, dissolve approximately equivalent amounts of the aldehyde (or ketone) and the solid reagent in the minimum volume of cold glacial acetic acid, and reflux for 15 minutes. The p-nitrophenyl-hydrazone separates on cooling or upon careful dilution with water. 

Chlorobenzaldehyde (2-nitrophenyl)hydrazone (1) can be transformed to the 1,2,5-triazocine system 2 on reduction.s... 

Chlorobenzaldehyde(2-nitrophenyl)hydrazone (3 g, 10.9 mmol) was heated under reflux with granulated tin (10 g) and coned hydrochloric acid (60 mL) for 1 h upon which an orange, clear solution was obtained, which became colorless on further heating. After the removal of tin, the solution was evaporated, almost to dryness, on a water bath to give a colorless, shiny, crystalline residue which was recrystallized (dil hydrochloric acid) to provide the hydrochloride mp 285 C. The free base was obtained as a colorless, crystalline mass after addition of NH3 to an aqueous solution of the hydrochloride, and was recrystallized (EtOH) to give shiny colorless plates mp 217-218 C. 

Enantiomerically pure nitrile imines (211) have also been generated by the lead tetraacetate oxidation of aldehydo sugar p-nitrophenyl hydrazones. Reaction with methyl acrylate gave the pyrazolines as a 1 1 mixture of the (55) and (5R) epimers, which were resolvable in some cases (116). 

Anhydrides of sugars1723 have also been obtained by intramolecular displacement of halide ions. Thus, for example, treatment of 3,4-di-0-acetyl-2-bromo-2-deoxy-D-xylopyranose (133) with (p-ni-trophenyl)hydrazine affords173 3,4-di-0-acetyl-2,5-anhydro-D-lyxose (p-nitrophenyl)hydrazone (135) and 3,4-di-0-acetyl-2,5-anhydro-D-xylose (p-nitrophenyl)hydrazone (136). The formation of two (p-nitrophenyl)hydrazones can be explained by an initial displacement of the bromine atom at C-2 by 0-5, to give 3,4-di-0-acetyl-2,5-... 

Regeneration of carbonyl compounds from certain derivatives. Ketones can be recovered in satisfactory yield from the phenylhydrazones, p-nitrophenyl-hydrazones, tosylhydrazoncs, oximes, and semicarhazones by reaction with 1 equivalent of (C6H,Se0)20. 2,4-Dinilrophenylhydrazones and N,N-dimethyl-hydrazones arc inert under even rather vigorous conditions. The reagent can also be used to regenerate aldehydes from oximes or tosylhydrazones. 

Direct cyclization of a related aminothiophene (48) occurred on treatment with phosphorus oxychloride to give 49,52 and ring closure between the thiophene ring and the side chain in the p-nitrophenyl-hydrazones (50) with polyphosphoric acid yielded 51. On heating, 2,3-diacetamidobenzo[ft]thiophene eliminated acetic acid and water to give 2-methylbenzothieno[2,3-d]imidazole (52),54,JJ but successful conditions could not be found for cyclization of 2-acetamido-3-phenyl-aminobenzo[6]thiophene.55... 

Dinitro-2-chloro-3-hydroxy-(4-nitrophenyl-hydrazone), dk red ndls(from AcOH), mp 277-79°(dec)(Refs 1 4) and... 

Di nitro-(p-anisaldehyde)-4 -nitrophenyl-hydrazone or 2,6-Dinitro-3-methoxybenz-cddehyde-4-nitrophenylhydrazone, It orange plates exploding at ca 260°. Was obtained by treating 2,6-dinitro-3-methoxybenzalde-hyde with p-nitrophenylhydrazone, as described in Ref 2... 

Dinitro-(p-anisaldehyde)-(4> -nitrophenyl-hydrazone), dk brn crysts, mp 275°. Was prepd by treating 3,5-dinitro-4-methoxybenz-aldehyde with p-nitrophenylhydrazone as described in Ref 2... 

Dinitrophenyl Semicarbazone hydrazone °C °C Oxime °C Phenylhydrazone °C p-Nitrophenyl hydrazone °C... 

Chi orohydroxy benzol dehyde-(4 nitrophenylhydrazone and Derivatives Chi orohydroxyben zaldehy de-(4-nitrophenyl-hydrazone) [called Chlor-oxy-benzaldehyd -(4-nitro-phenylhydrazon in Ger], 02N.-CSH4.NH.N CH.CSH3C1.0H mw 291.69,... 

This alkaloid, isolated from a calabash (34), has color reactions, Re values, aUV-spectrum, and a melting point of itspicrate (179°) identical with those of C-fluorocurine. However, unlike the latter alkaloid, it does not form a sparingly soluble iodide or a sparingly soluble p-nitrophenyl-hydrazone. Its relationship to C-fluorocurine is at present obscure. 

In connection with preliminary structural work on the hexitols, an unexpected result arose during attempted identification, by conversion into a (p-nitrophenyl)hydrazone, of the dialdehydes (8) or (9), formed by periodic acid oxidation of tbe anhydrodeoxyhexitols (6) and (7), or (21) and (22). The dialdehydes (8) were cleaved to form glyoxal and a 2-deoxytetrose [isolated as the (p-nitrophenyl)hydra-zone ]. 

Osazone and (p-nitrophenyl)hydrazone formation without desul-fonylation has been accomplished in aqueous ethanolic acetic acid with 3,6-anhydro-5-0-p-tolylsulfonyl-D-glucofuranose. With 6-0-(me-thylsulfonyl)- and 6-O-p-tolylsulfonyl-D-galactose in methanol at room temperature for 2 days, the corresponding (2,4-dinitro-, (N-benzyl-, and (2,5-dichloro-phenyl)hydrazones were readily obtained. How-... 

Reaction of the dialdehyde with phenylhydrazine gave a derivative which formed an amorphous diphenylformazan (which, further, gave a monoacetate). Structure (55) was proposed for the formazan. Reaction of the dialdehyde with (p-nitrophenyl) hydrazine gave an amorphous mono-hydrazone, which was hydrolyzed by acid to glyoxal bis[(p-nitrophenyl)-hydrazone) and glycerose (as pyruvaldehyde). Structure (56) was assigned... 

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