Studies on dehydro-l-ascorbic acid 2-arylhydrazones: conversion into substituted triazoles and pyrazolinediones

The 2-p-chlorophenylhydrazone of dehydro-L-ascorbic acid was reacted with hydroxyamine giving the 3-oxime. Dehydrative cyclization of the latter gave the triazole derivative. The lactone ring cleaved upon treatment with hydrazine, methylamine or dimethylamine giving the corresponding triazole carboxamide derivative. Periodate oxidation of the triazole carboxamide gave the 3-formyltriazole which upon reduction gave the corresponding alcohol, characterized as its monoacetate. The 2-hydrazone was condensed with arylhydrazine giving the mixed bis- hydrazones, which underwent rearrangement to the pyrazolinediones and gave the bicyclic 3,6-anhydro derivatives upon treatment with cupric chloride

Studies on dehydaro-d-erythro-and l-threo-ascorbic acid 2-arylhydrazone-3-oximes and mixed bishydrazones: conversion into substituted triazoles and pyrazolinediones

Reaction of p-nitrophenyltriazole of dehydro-D-erythro-ascorbic acid [I] with hydrazine hydrate in MeOH yielded the corresponding triazole hydrazide [II] which gave the triacetyl derivative [III]. Periodate oxidation of [II] gave the 3-formyltriazole derivative [IV] which formed a triacetyl derivative [VI]. The 3-formyl derivative [IV] was condensed with hydrazine hydrate and O-phenylenediamine to give compounds [VII] and [VIII], respectively. Treatment of [I] with ammonium hydroxide solution and MeOH gave the triazole carboxamide [IX] which produced two different acetyl derivatives [X] and [XI]. The p-nitrophenylhydrazone zone of dehydro-D-erythro-[XII] and dehydro-L- threo-ascorbic acid [XIII], reacted with phenylhydrazine to give the mixed bisarylhydrazones [XIV] and [XV], respectively, which formed the diacetyl derivatives [XVI] and [XVII]. Compound [XIV] underwent rearrangement to the corresponding pyrazole derivative [XVIII] which gave the acetyl product [XIX]. Periodate oxidation of [XVIII] gave the 3-formylpyrazole [XX] which yielded different condensation products [XXI]-[XXV]. Cupric chloride oxidation of [XV] gave the 3,6-anhydro derivative [XXVI] which characterized as its monoacetyl derivative [XXVII]

Studies on dehydro-l-ascorbic acid 2-nitrophenyl-hydrazone: conversion into pyrazolinedione and thiadiazoline derivatives

The p-nitrophenylhydrazone of dehydro-L-ascorbic acid [I] reacted with methylhydrazine in MeOH giving the pyrazolinedione [V] and not the expected mixed bishydrazone [III]. The pyrazole derivative gave the tri-O-acetyl and tri-O-benzoyl derivatives [VI] and [VII], respectively. Periodate oxidation of [V] gave the 3-arboxaldehyde derivative [VIII] which was reduced by NaBH4 to the corresponding alcohol [IX] which formed the monoacetyl derivative [X]. The 3-carboxaldehyde condensed with hydroxylamine to give the 3-hydroxyiminomethyl derivative [XI], which upon acetylation gave the 3-acetoxyiminomethyl derivative [XII]. Similarly, benzoylation of [XI] gave the 3-benzoyl derivative [XIII]. The 3-thiosemicarbazone [XIV] of [VIII] gave the bicyclic derivative [XV] upon treatment with benzoyl chloride in pyridine. Treatment of [XV] with hydrazine hydrate gave [XVII]. which upon benzoylation gave [XVIII]

on the rearrangement of dehydro-L-ascorbic acid mixed bishydrazone to 4,5-pyrazolinediones

Dehydro-L-ascorbic acid 2-[p-nitrophenylhydrazone] [I] reacted with p- sulfamylphenylhydrazine giving the mixed bishydrazone II, which gave the di-O-acetyl- and di-O-benzoyl derivatives III and IV. II underwent rearrangement by hydrazine hydrate to the pyrazole derivatives VI and VII. Periodate oxidation of V gave the 3-carboxaldehyde derivative VIII, which was reduced by sodium borohydride to the corresponding alcohol IX that gave monoacetyl derivative X. Compound VIII gave a number of condensation products XI-XVII. Mild oxidation of II with cupric chloride gave the 3,6-anhydro derivative XVIII that gave the monoacetyl and monobenzoyl derivatives XIX and XX, respectively. Acetylation of the 3-hydroxyiminomethyl derivative XI gave the 3-acetoxyiminomethyl derivative XXI. Similarly, benzoylation of XI gave the 3-benzoyl derivative XXII. The 3-thiosemicarbazone XVII, gave the bicyclic derivative XXIII upon acetylation. Similarly, benzoylation of XVII gave XXIV

Some reactions of 3-formyl-4,5- [1H] pyrazolinedione-4- [phenylhydrazone]

The 3-hydroxyiminomethylpyrazole derivative II existed in ketoenol as evidenced by the production of two acetyl derivatives IV and V, respectively. The enol form III gave the benzoyl derivative VI. Treatment of III with benzoyl chloride in pyridine, for a long time, gave the bicyclic derivative VII. The 3-thiosemicarbazone derivative also existed in ketoenol forms. Both gave the acetyl bicyclic derivatives X and XI upon acetylation. The enol form IX also formed the benzoyl bicyclic derivative XII. The 3-formyl derivative I condensed with hydrazine hydrate and methylhydrazine to give the corresponding hydrazones XIII and XIV, characterized by giving the acetyl derivatives XVII and XVIII, respectively

Reduction products and bromodeoxy derivatives of dehydro-L-ascorbic acid 2- [phenylhydrazone]

Dehydro-L-ascorbic acid 2-[phenylhydrazone] [I] was reduced by sodium borohydride to 3,6-anhydro-L-xylo-2-hexulosono-1,4-lactone-2- [phenylhydrazone] [II] which gave a mono-O-acetyl- and mono-O-benzoyl derivatives III and IV, respectively. Treatment of I with HBr/AcOH gave the 5,6-dibromo-5,6-dideoxy derivatives VI that gave a number of condensation products VII-XI, while treatment of I with methylhydrazine gave 1-methyl-3-[2,3-dibromo-2,3-dideoxy-L-threo- glycerol-1-yl]- 4,5-pyrazolinedione-4-[phenylhydrazone] [XII]

On the rearrangement of dehydro-l-ascorbic acid 2-p-mitcphenyl hydmzene to nitrogen heteiocyeles

The 3-hydroxyiminomethylpyrazole derivative II existed in keto-enol as evidenced by production of two acetyl derivatives IV and V, respectively. The enol form III gave the benzoyl derivative VI. Similarly, the 3-formylhydranone derivative VII gave the acetyl derivative IX. Condensation of VII with o- and m-nitrobenzaldehyde gave the benzylidene derivatives X and XI, respectively. The thiosemicarbazone XII also existed in the keto-enol forms. Both gave the acetyl bicyclic derivatives XIV and XV upon acetylation, and the enol form XIII gave the benzoyl derivative XVI. The 2-p- nitrophenylhydrazone 3-oxime XVII gave the triazole derivative XVIII upon oxidation with cupric chloride. The 2-p-nitrophenylhydrazone 3- oxime XVII gave the triazole derivative XVIII, which yielded the acetyl derivative XIX. Mild acetylation of XVII with AcOH gave the monoacetyl derivative XX which upon acetylation with Ac2O gave the triacetyl derivative XXI