Showing papers on "Hydrazone published in 1968"

Investigations on Steroids. XI. Synthesis of Steroidal Oxazole, Imidazole, and Triazole

Abstract: Steroidal oxazoles, imidazoles, and triazoles were synthesized for biological studies. 2α-Acetoxy-or 2α-bromo-3-ketones of androstane and cholestane series were converted into 2'-methylsteroidal [3, 2-d] oxazoles (III) by reaction with ammonium acetate. Reductive acetylation of 2-hydroxyimino-3-oxo steroids (V) gave 2α-acetamido-3-ketones (VI) which were cyclized by the use of sulfuric acid to 2'-methyl-steroidal [2, 3-d] oxazoles (XI). 2'-methyl-steroidal [2, 3-d] imidazoles (XII) were prepared from VI by reaction with ammonium acetate. 2α-Amino-3-ketone hydrochlorides, obtained by catalytic hydrogenation of V, were converted by reaction with thiocyanate into steroidal [2, 3-d] imidazoline-2'-thiones which were desulfurized to afford imidazoles (XIV). Androst-4-eno[2, 3-d]-triazoles (XX) were prepared from the 2-acetoxymethylene-3-ketone via the 2-hydroxyimino-3-one hydrazone by application of the established procedures. The ORD (and CD) data of VI and the corresponding 3β-alcohol (VIIId) are presented.

The reactions of substituted 2-alkyl-2H-tetrazol-5-ylhydrazones with bromine and lead tetra-acetate: routes to 6-aryl-1-methyl[1,2,4]triazolo[4,3-d]tetrazoles

Abstract: 2-Methyl-2H-tetrazol-5-ylhydrazones were generally more reactive towards electrophilic reagents than the 1-methyl isomers and their reactions involved considerable amounts of decomposition. When treated with bromine the hydrazones yielded hydrazidic bromides. These latter materials were much less reactive than the 1-methyl isomers and were solvolysed ca. 200 times more slowly in dioxan–water (90% v/v). The products of the solvolysis were new triazolotetrazoles. This reaction, which probably involved the formation of an azocarbonium ion intermediate which underwent nucleophilic ring closure with the tetrazole ring as nucleophile, was in competition with nucleophilic attack by solvent water, and was eliminated when a highly nucleophilic solvent such as aniline was used. When the tetrazolylhydrazones were treated with lead tetra-acetate, cyclisation to the triazolotetrazoles constituted only a minor reaction. The major reaction involved here was an acetoxylation of the hydrazone, to give an N-acetyl hydrazide. Deacetylation of these N-acetyl hydrazides afforded a convenient conversion of the parent hydrazones into hydrazides.

Reversible and irreversible electron shifts in reactions of steroidal 20-keto-16,17-oxides with hydrazine hydrate

Abstract: 1. Decreasing the concentration of base in the reduction of keto epoxides by the Huang-Minlon method shifts the reaction in the direction of pyrazole formation, from which it follows that reversible and irreversible electron shifts in the hydrazone fragment of the side chain are competing processes, dependent on the base concentration. 2. The indicated modification of the reaction makes it possible to significantly (up to 55–70%) increase the yield of pyrazoles.

Heterocyclic imines and amines. Part XI. Reactions of o-cyanocinnamonitriles and related compounds with nitrogen bases

Abstract: Hydroxylamine adds under mild conditions to both nitrile groups of the o-cyanocinnamonitriles to give amidoximes whereas piperidine and ammonia add to the side-chain double bond to give β-amino-nitriles. Hydrazine adds at the β-position, and this is followed by cyclisation onto the o-substituent and substitution of reactive functional groups to yield 2-amino-3-cyanomethylisoindolin-1-one hydrazone. A similar reaction is observed with o-carbamoyl-trans-cinnamamide in addition to the base-catalysed cyclisation to a 2-unsubstituted isoindolinone. Under more vigorous conditions o-cyano-cis-cinnamamide gives a phthalazine, evidently through dehydrogenation of the intermediate β-adduct.Light absorptions and 1H n.m.r. results provide structural evidence. Amidoxime-I and -II bands in the i.r. are recognised.

Separation of some aromatic carbonyl compounds by thin layer chromatography of their isonicotinoyl hydrazone derivatives

Abstract: The separation of 13 isonicotinoyl hydrazones derived from some isomeric aromatic carbonyl compounds by thin layer chromatography is described. Methods for separating and identifying the components of complex mixtures of these hydrazones are discussed.

The chemistry of pyrazolidine

Abstract: 1. The IR and electronic absorption spectra and the chromatographic behavior of the diazo coupling products of 1,2-diphenyl-3, 5-dioxopyrazolidine have been examined. 2. A hydrazone structure with intramolecular hydrogen bonding has been assumed.