Showing papers on "Hydrazone published in 1990"

Fluorogenic reagents: 4-aminosulphonyl-7-hydrazino-2,1,3-benzoxadiazole, 4-(N,N-dimethylaminosulphonyl)-7-hydrazino-2,1,3-benzoxadiazole and 4-hydrazino-7-nitro-2,1,3-benzoxadiazole hydrazine for aldehydes and ketones

Abstract: Fluorogenic reagents for aldehydes and ketones, viz., 4-aminosulphonyl-7-hydrazino-2,1,3-benzoxadiazole (ABD-H) and 4-(N,N-dimethylaminosulphonyl)-7-hydrazino-2,1,3-benzoxadiazole (DBD-H) and also purified 4-hydrazino-7-nitro-2,1,3-benzoxadiazole hydrazine (NBD-H.NH2NH2) were synthesised. These reagents are not fluorescent; however, their reaction products with aldehydes and ketones fluoresce at wavelengths from 548 to 580 nm with excitation from 450 to 470 nm. Both ABD-H and DBD-H exhibited similar reactivity and were more reactive than NBD-H.NH2NH2. The respective pseudo-first-order reaction rate constants for the production of the hydrazone of propionaldehyde with ABD-H, DBD-H and NBD-H.NH2NH2 were 8.9 × 10–2, 7.2 × 10–2 and 4.2 × 10–2 min–1(the reaction was carried out in 0.0025% trifluoroacetic acid in acetonitrile at room temperature, 22 °C). The detection limits using the manual method (i.e., measurement of fluorescence intensity) for the hydrazones of aldehydes and ketones with ABD-H, DBD-H and NBD-H.NH2NH2 were in the µM range. The substrate blank fluorescence with ABD-H was half of that with DBD-H and NBD-H.NH2NH2. The reaction products were separated and analysed by reversed-phase high-performance liquid chromatography (HPLC) with spectrofluorimetric detection. The detection limits for propionaldehyde were 1040, 120 and 35.0 fmol with ABD-H, DBD-H and NBD-H.NH2NH2, respectively, and those for heptan-4-one were 2690, 560 and 673 fmol, respectively. Of the three reagents, DBD-H is recommended for the sensitive detection of ketones and NBD-H.NH2NH2 for the detection of aldehydes. The detection limits for aldehydes and ketones by HPLC were in the sub-pmol to pmol range.

Synthesis of .beta.-lactams via cycloaddition of hydrazones with phenoxyketene

Abstract: Phenoxyketene is capable of annelating the disubstituted hydrazones to afford stereoselectively cis-monocyclic β-lactams with a 1-amino functionality. The ease of cycloaddition is governed by substituents on the azomethine carbon as well as on the hydrazone nitrogen. The 4-disubstituted β-lactams (4a-c and 6a-b) were prepared through the reaction of N,N-diphenylhydrazones and N-methyl-N-phenylhydrazones of ketones with phenoxyacetyl chloride/Et 3 N in dichloromethane. A similar reaction using aldehyde and ketone hydrazones, derived from N,N-dimethylhydrazine, produced 4-monosubstituted (8a-d) as well as 4-disubstituted (8e-1) β-lactams in good yields

Synthesis of (±)-pisiferin, (±)-pisiferol, and related compounds by intramolecular [4 + 2]cycloaddition

Abstract: Thermolysis of the olefinic benzocyclobutene (17) afforded the tricyclic compounds (18a) and (18b), whose sequential reduction, via the aldehyde (19), gave rise to the pisiferol derivatives (20a) and (20b). Since (20a) was transformed into pisiferol (2), pisiferic acid (3), and methyl pisiferate (4), this synthesis constitutes their formal synthesis. Wolff–Kishner reduction of the hydrazone of (19b) yielded the known tricyclic compound (21), which has previously been transformed into xanthoperyl methyl ether (22). Furthermore, the predominantly cis used mixture of compound (18)(a/b= 1 : 4) was converted into the predominantly trans-fused mixture (a/b= 3 : 1) using catalytic hydrogenation of the enone (24) as a key reaction. Finally, a skeletal rearrangement of an abietane-type into a 9(10→20)abeo-abietane-type compound was demonstrated. Dehydration of the alcohol (20a) afforded the methyl ether (26) and its isomer (27) in the ratio of 3 : 1 as an inseparable mixture. Demethylation of the mixture (26) and (27) provided pisiferin (1) and compound (28). Interestingly, rearrangement of the cis-fused compound (20b) formed the methyl ether (27) as a sole product, which was converted into isopisiferin (29).

Dimroth‐Umlagerung von Iminen des 1,5‐Diaminotetrazols

Abstract: Dimroth Rearrangement of Imines Derived from 1,5-Diaminotetrazole Heating the imines 1 in dimethyl sulfoxide (or partly in xylene) provides hydrazones such as 2. The reaction is greatly favoured by electron-withdrawing groups attached to the imine carbon atom.

A tandem denitration-deoxygenation of .alpha.-nitro ketones via (p-tolylsulfonyl)hydrazones with lithium aluminum hydride: a practical synthesis of (Z)-9-tricosene, the sex pheromone of the housefly (Musca domestica)

Abstract: Now, we report a tandem denitration-deoxygenation sequence performed by reduction of (p-tolylsulfonyl)-hydrazones of α-nitro ketones with lithium aluminum hydride in tetrahydrofuran at 60°C

Nickel(II) chelates of Schiff bases derived from isatin and chromone with amino acids and substituted hydrazines

Abstract: Nickel(II) complexes of the Schiff base derivatives of isatin with glycine, β-alanine, anthranilic acid, S-methyl hydrazine carbodithioate, the ammonium salt of hydrazine carbodithioate, thiosemicarbazide, and benzoyl hydrazine, and nickel(II) complexes of 6-formyl-7-hydroxy-5-methoxy-2-methyl chromonelideneS-methyl hydrazine carbodithioate and benzoyl hydrazone, were prepared and characterized by elemental analysis, i.r., u.v.-vis spectra and magnetic measurements. All the complexes are octahedral.

Theoretical calculations and experimental studies on the electronic structures of hydrazones and hydrazone radical cations: formaldehyde hydrazone and benzaldehyde diphenylhydrazones

Abstract: Etude de la geometrie et de la structure electronique a l'aide de mesures electrochimiques, des spectres d'absorption electroniques et de calculs ab initio SCF: l'hydrazone du formaldehyde n'est pas plane a l'inverse de son radical cationique, alors que dans les hydrazones de benzaldehyde, on trouve une structure plane ou presque (augmentation de la conjugaison p-π entre doublet electronique libre sur le N amino et les cycles phenyle)

Synthesis, Characterization, IR and Electronic Spectra, Magnetic Moments and Biological Activity of Trinuclear Nickel(II) Tetrathiocyanato Bis Argentate(I) Complexes with Hydrazides and Hydrazones

Abstract: Nickel (II) complexes of the type Ni[Ag(SCN)2]2.L [where L = benzoic acid hydrazide (BH), salicylic acid hydrazide (SH), anthranilic acid hydrazide (AH), isonicotinic acid hydrazide (INH), oxaldihydrazide (ODH), malondihydrazide (MDH) and their isopropanone derivatives, viz., isopropanone benzoyl hydrazone (IBH),-salicyl-hydrazone (ISH), -anthranoylhydrazone (IAH) and -isonicotinoyl hydrazone (IINH)] were synthesised and characterized with the help of elemental analyses, electronic, IR and magnetic moment data. The complexes are insoluble in common organic solvents, partially dissociate or dissolve in DMF and DMSO, have coordinated hydrazide or hydrazone ligands and bridging SCN groups. Nickel (II) in the complexes is spin free and has a pseudo-octahedral environment.

Synthesis and Chromogenic Properties of Some Water-Soluble 5-Nitro-2-Pyridylhydrazones

Abstract: Four new water-soluble hydrazones, α-(5-nitro-2-pyridyl)hydrazono-α-(2-quinolyl)-3-toluenesulfonic acid, α-(5-nitro-2-pyridyl)hydrazono-α-(2-thiazolyl)-3-toluenesulfonic acid, α-(2-benzothiazolyl)-α-(5-nitro-2-pyridyl)hydrazono-3-toluenesulfonic acid, and α-(2-benzimidazolyl)-α-(5-nitro-2-pyridyl)hydrazono-3-toluenesulfonic acid, were synthesized. Their proton dissociation constants were determined spectrophotometrically. The chromogenic properties of the synthesized hydrazones and their reactions with metal ions were investigated spectrophotometrically in detail. The results revealed that the synthesized hydrazones react with various metal ions including transition metal ions, especially with cadmium(II), nickel(II), and zinc(II) to form stable colored complexes with very large apparent molar absorptivities, so that they were found to be all very useful as highly sensitive spectrophotometric reagents.

Synthesis of some new hydrazide-hydrazones, thiosemicarbazides, thiadiazoles, triazoles and their derivatives as possible antimicrobials.

Abstract: The title compounds were prepared by reacting [(4,5-diphenyl-1H-imidazol-2-yl)thio]acetic acid hydrazides 6 and 7 with aromatic aldehydes to give the corresponding hydrazones 6a-m and 7a-d or with isothiocyanates to afford the corresponding thiosemicarbazides 8a-c and 9. 8a-c and 9 were cyclized into triazoline-5-thiones 10a-c and 11 in the presence of sodium hydroxide or into 1,3,4-thiadiazoles 14a-c and 15 in the presence of sulfuric acid. On the other hand, 10c and 11 were also reacted with alkyl halides to obtain their thioether derivatives, 12a,b and 13. All the synthesized compounds were characterized by their elementary analysis and by using UV, IR, NMR and mass spectrometry. 6b, c, f, h-k, m, 7, 7d, 8c, 9, 10c, 11, 12a-b, 13, 14 and 15 were tested for antimicrobial activity, but no significant activity was observed.

Structure of the reaction products from dehydroascorbic acid analogues, o-phenylenediamine, and arylhydrazines. X-Ray molecular structure of 3-[L-threo-2,3,4-triacetoxy-1-(phenylhydrazono)butyl]quinoxalin-2(1H)-one hemihydrate

Abstract: Acetylation of the product obtained from successive reaction of dehydro-L-ascorbic acid with o-phenylenediamine and phenylhydrazine gave 3-[L-threo-2,3,4-triacetoxy-1-(phenylhydrazono)butyl]quinoxalin-2(1H)-one (3) rather than the cyclic structure (4) previously assigned for the reaction product. The structure of compound (3) was confirmed based on 1H NMR, 13C NMR, and X-ray analysis. Reinvestigation of the reaction of 5-phenylfuran-2,3,4(5H)-trione (6) with o-phenylenediamine and an arylhydrazine led to the isolation of two components (7) and (10). The former was found to exist in dimethyl sulphoxide solution as a tautomerie mixture of hydrazone imine and diazenyl enamine. Attempted acetylation of compound (7) afforded the furo[2,3-b]quinoxaline ring system (8).

New uranyl(VI) complexes with hydrazones derived from aliphatic and aromatic acid hydrazides containing dihydroxo bridges

Abstract: Several new uranyl(VI) complexes of hydrazones, derived from formoyl-, acetoyl-, butroyl-, caproyl-, salicyloyl-, oxaloyldi-, malonoyldi-, and adipolyldi-hydrazines and benzaldehyde or salicylaldehyde have been prepared in absolute EtOH and in the presence or absence of AcONa. The complexes have been characterized by elemental analyses, molar conductivities, spectral (u.v., i.r, n.m.r.,) and magnetic measurements. I.r. spectral data suggest that the ligands coordinate in a bi-, tri- and/or tetradentate fashion in the enol form, and that proton displacement proceedsvia the enolized carbonyl oxygen solely in the benzaldehyde hydrazone complexes and through the OH (phenolic) in the salicylaldehyde hydrazone complexes. Moreover, the spectral data show the existence of dihydroxo bridges for benzaldehyde hydrazone complexes. The role of the OH (phenolic) as well as the presence or absence of NaOAc on the properties of the latter complexes is discussed.

Pyruvic Acid Dimethylhydrazone. A Synthetic Equivalent of the Pyruvic Acid Dianion

Abstract: The pyruvic acid dimethyl hydrazone can be easily prepared in ether. This compound, after deprotonation with alkyllithium, forms a strong nucleophile which on treatment with electrophiles and acidi...

Elektrophile β-Bromierung und nucleophile α-Methoxylierung α,β-ungesättigter Carbonylverbindungen

Abstract: Electrophilic β-Bromination and Nucleophilic α-Methoxylation of α,β-Unsaturated Carbonyl Compounds Oximes 29a, b, semicarbazones 11a–d, dimethylhydrazones 4, and [3-methyl-2(3H)-benzothiazolylidene]hydrazones 23a–c of unsaturated aldehydes and ketones are brominated at the β-carbon by an addition-elimination sequence ( 21a,b, 13a–d, 7, and 27c, respectively). When unsaturated ketone hydrazones are treated with bromine and methanol the α-methoxy-β-bromo derivatives 35a–c are obtained, which after hydrolysis and hydrobromic acid elimination give α-methoxy substitution products 36a–c of the starting compounds.

Hydrazones and electrophotographic photoreceptors comprising them

Abstract: A hydrazone compound represented by the following formula (I): ##STR1## wherein R 1 and R 2 each are an aryl group or collectively with the carbon to which they are attached form a polycyclic group; R 3 represents a hydrogen or halogen atom or an alkyl or phenyl group; and R 4 and R 5 each represent an alkyl, aralkyl or aryl group, with the proviso that at least one of R 4 and R 5 is an aryl group, is useful as a charge-transporting material in an electrophotographic photoreceptor and are produced by condensing the corresponding aldehyde with the corresponding H 2 N--NR 4 R 5 hydrazine.

Processes for the preparation of pterin derivatives

Abstract: A process of preparing l-biopterin is disclosed which comprises the steps of: Subjecting to selective Grignard reaction D-ribose having the hydroxyl groups in the 2- and 3-positions protected by an acetal group to give 6-deoxy-3,4-O-­alkylidene allitol; subjecting the 1- and 2-positions of said allitol to oxidative cleavage to form 5-deoxy-2,3-O-alkylidene-L-­ribose followed by deacetalization to give 5-deoxy-L-ribose; reacting 5-deoxy-L-ribose with a hydrazine compound to form a 5-deoxy-L-ribose hydrazone compound; and subjecting said hydrazone compound to condensation reaction with an acid addition salt of 4-hydroxy-2,5,6-­triaminopyrimidine followed by oxidation.