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Showing papers on "Hydrazone published in 2002"



Journal ArticleDOI
04 Jul 2002-Farmaco
TL;DR: Both hydrazone products, ethyl 2-[(3,5-dimethylpyrazole-4-yl)hydrazono]-3-oxobutyrate and methyl 2-[4-methoxy-3-OxobUTyrate (3e) showed 29 and 28% inhibition against M. tuberculosis, respectively.
Abstract: Several new hydrazone derivatives were prepared by the reaction of some active hydrogen compounds with the diazonium salts of 4-amino-3,5-di/1,3,5-trimethylpyrazoles at 0-5 degrees C. Structures of the new substances were confirmed using UV, IR, 1H NMR, 13C NMR and EI-mass spectral data. In vitro antituberculosis activity of these compounds were tested on Mycobacterium tuberculosis H37Rv at 6.25 microg/ml. Both hydrazone products, ethyl 2-[(3,5-dimethylpyrazole-4-yl)hydrazono]-3-oxobutyrate (3d) and methyl 2-[(3,5-dimethylpyrazole-4-yl)hydrazono]4-methoxy-3-oxobutyrate (3e) showed 29 and 28% inhibition against M. tuberculosis, respectively.

139 citations


Journal ArticleDOI
TL;DR: Molecular modeling has provided insight into the structural basis for the anti-metallo-β-lactamase activity exhibited by this family of N-arylsulfonyl hydrazones.
Abstract: Members of a family of N-arylsulfonyl hydrazones have been identified as novel inhibitors of IMP-1, a metallo-β-lactamase of increasing prevalence. Structure-activity relationship studies have indicated a requirement for bulky aromatic substituents on each side of the sulfonyl hydrazone backbone for these compounds to serve as efficient inhibitors of IMP-1. Molecular modeling has provided insight into the structural basis for the anti-metallo-β-lactamase activity exhibited by this class of compounds.

107 citations


Journal ArticleDOI
TL;DR: The indium-mediated radical addition to an electron-deficient C=C bond also proceeded effectively to provide the new carbon-carbon bond-forming method in aqueous media.

94 citations


Journal ArticleDOI
TL;DR: Catalytic asymmetric intramolecular [3 + 2] cycloaddition of hydrazone/olefins has been attained and the desired pyrazolidine derivatives were obtained in high yields with high selectivities.
Abstract: Catalytic asymmetric intramolecular [3 + 2] cycloaddition of hydrazone/olefins has been attained. In the presence of a chiral zirconium catalyst prepared from zirconium alkoxide and a BINOL derivative, the desired pyrazolidine derivatives were obtained in high yields with high selectivities. The products were easily converted to 1,3-diamine or beta-aminonitrile derivatives by N-N bond cleavage.

91 citations


Journal ArticleDOI
TL;DR: In this article, an efficient and scalable process for the human immunodeficiency virus (HIV) protease inhibitor BMS-232632 1-[4-(pyridin-2-yl)phenyl]-5(S)-2,5-bis{[N-(methoxycarbonyl)-l-tert-leucinyl]-amino}-4(S)hydroxy-6-phenyl-2hexane, is described.

77 citations


Journal ArticleDOI
TL;DR: A tridentate ONN donor Schiff-base hydrazone ligand, H2L, was synthesized by the condensation of 2-amino-4-hydrazino-6-methyl pyrimidine with o-hydroxyacetophenone as discussed by the authors.
Abstract: A tridentate ONN donor Schiff-base hydrazone ligand, H2L, was synthesized by the condensation of 2-amino-4-hydrazino-6-methyl pyrimidine with o-hydroxyacetophenone. The structure of the ligand was elucidated by IR and 1H NMR spectra which indicated the presence of three different coordinating groups, the oxygen atom of the phenolic OH group, the nitrogen atom of the azomethine, C=N, group and one of the nitrogen atoms of the heterocyclic ring. The ligand behaves either as a tridentate (N2O sites) neutral, mono- or di-basic ligand or as a bidentate (NO sites) monobasic ligand depending on the pH of the reaction medium and the metal ion. The mass spectrum of the ligand showed the presence of the molecular ion peak. Different types of metal complexes, mononuclear such as [(HL)M(OAc)]·xH2O (M = Cu or Zn), [(HL)M(OAc)H2O]·xH2O (M = Ni or UO2), [(HL)Co(OH2)Cl]·2H2O, [(H2L)FeCl3]·3½H2O, [(L)FeCl(H2O)2]· 2¼H2O, [(HL)L'FeCl(H2O)]·H2O (L' = 8-hydroxyquinoline, 8-HQ), [(HL)L'FeCl]Cl·xH2O (L' = 1,10-phenanthroline, p...

74 citations


Journal ArticleDOI
TL;DR: A major metabolite on incubation of IMI in the human microsome-NADPH system is tentatively assigned by LC/MS as a 1,2,4-triazol-3-one derived from the hydrazone, which is considered here together (referred to as the Hydrazone) for quantitation.
Abstract: The major insecticide imidacloprid (IMI) is known to be metabolized by human cytochrome P450 3A4 with NADPH by imidazolidine hydroxylation and dehydrogenation to give 5-hydroxy-imidacloprid and the olefin, respectively, and by nitroimine reduction and cleavage to yield the nitrosoimine, guanidine, and urea derivatives. More extensive metabolism by human or rabbit liver microsomes with NADPH or rabbit liver cytosol without added cofactor reduces the IMI N-nitro group to an N-amino substituent, i.e., the corresponding hydrazone. A major metabolite on incubation of IMI in the human microsome-NADPH system is tentatively assigned by LC/MS as a 1,2,4-triazol-3-one derived from the hydrazone; the same product is obtained on reaction of the hydrazone with ethyl chloroformate. The hydrazone and proposed triazolone are considered here together (referred to as the hydrazone) for quantitation. Only a portion of the microsomal reduction and cleavage of the nitroimine substituent is attributable to a CYP450 enzyme. The...

65 citations


Journal ArticleDOI
TL;DR: In this paper, a combination of sulfanyl radical addition-cyclization of the oxime ethers and hydrazones connected with alkenes and subsequent conversion of a phenylsulfanylmethyl group to a carboxyl group provides a novel method for the construction of the cyclic β-amino acids.

48 citations



Journal ArticleDOI
TL;DR: The asymmetric total synthesis of (-)-callystatin A has been achieved and the key steps generating the stereogenic centers rely on the asymmetric alpha-alkylation of aldehydes or ketones exploiting the SAMP/RAMP hydrazone alkylation methodology.

Journal ArticleDOI
TL;DR: The SAMP-hydrazone of 2,2-dimethyl-1,3-dioxan-5-one represents a valuable chiral dihydroxyacetone equivalent and protected ketodiols in excellent diastereo- and enantiomeric excesses.
Abstract: The SAMP-hydrazone of 2,2-dimethyl-1,3-dioxan-5-one represents a valuable chiral dihydroxyacetone equivalent. Asymmetric mono- or α,α'-bisalkylations followed by auxiliary cleavage leads to the corresponding mono- or α,α'-disubstituted. acetonide protected ketodiols in excellent diastereo- and enantiomeric excesses.

Journal ArticleDOI
TL;DR: In this paper, a reduction of β-asarone with DDQ gave trans-2,4,5-trimethoxycinnamaldehyde, which on treatment with p-toluenesulfonyl hydrazine provided corresponding α,β-unsaturated hydrazone derivative.
Abstract: Oxidation of β-asarone (2) with DDQ gave trans-2,4,5-trimethoxycinnamaldehyde (3), which on treatment with p-toluenesulfonyl hydrazine provided corresponding α,β-unsaturated hydrazone derivative (4). Reduction of 4 with sodium borohydride in acetic acid afforded γ-asarone (1) in 43% yield.

Journal ArticleDOI
TL;DR: In this paper, a 13C NMR and UV-visible study of the tautomeric behavior of azo-functionalized PAMAMAM (polyamidoamine) dendrimers and the corresponding model compounds in a variety of solvents is reported.

Journal ArticleDOI
TL;DR: It was concluded that all condensations/cycloeliminations, except with hydrazine itself, were more effective with catalysts or higher reaction temperatures.
Abstract: An efficient and selective method for the synthesis of spiro-fused (C5)-isoxazolino-(C4)-pyrazolones (C) is reported. The process consists of utilizing the Baylis−Hillman reactionor a quicker, stepwise MAC procedureto give I followed by 1,3-dipolar cycloaddition and Swern oxidation to give β-ketoesters H, which were condensed with hydrazine derivatives to provide hydrazones that underwent cycloelimination. These novel spiro-fused (C5)-isoxazolino-(C4)-pyrazolones were confirmed by spectroscopic analysis as well as single-crystal X-ray of 5. We also concluded that all condensations/cycloeliminations, except with hydrazine itself, were more effective with catalysts or higher reaction temperatures. For example, TiCl4 was an efficient catalyst for hydrazone formation and cycloelimination with methylhydrazine, while phenyl-, benzyl-, and (4-methoxyphenyl)hydrazine reacted effectively without catalyst in refluxing xylene.

Journal ArticleDOI
TL;DR: The first asymmetric synthesis of conium conium alkaloid (−)-α-conhydrine is reported in this paper, starting from a protected glycol aldehyde hydrazone as chiral precusor, a short route based on α-alkylation/1,2addition methodology has been developed.
Abstract: The first asymmetric synthesis of the conium alkaloid (−)-α-conhydrine is reported. Starting from a protected glycol aldehyde hydrazone as chiral precusor, a short route based on our α-alkylation/1,2-addition methodology has been developed. After cleavage of the auxiliary and simultaneous deprotection, the concluding ring closure is accomplished under reductive amination conditions. The title compound is obtained in moderate overall yield and in excellent diastereo- and enantiomeric excess (d.e., e.e. >96%). Single-crystal X-ray crystallography as well as 1H NMR NOE experiments confirm the expected relative and absolute (2R,7S)-configuration of the product.

Journal ArticleDOI
TL;DR: OEt2-catalyzed thiolysis of the hydrazone C=N bond affords the corresponding dithioketals 7 in optically pure or enantiomerically enriched form.

Journal ArticleDOI
TL;DR: In this paper, new derivatives of azobenzene crown ethers have been obtained, which include compounds with alkyl, alkoxy, hydroxy or dimethylamino group in aromatic residue(s) as side substituents.

Journal ArticleDOI
TL;DR: An enantioselective synthesis of E/Z-13,14-dinor-inter-p-phenylene carbacyclin (E/Z -2d) by a new strategy has been realized that holds the prospect of serving as a general route for carba-prostacyClin analogues.
Abstract: An enantioselective synthesis of E/Z-13,14-dinor-inter-p-phenylene carbacyclin (E/Z-2d) by a new strategy has been realized that holds the prospect of serving as a general route for carba-prostacyclin analogues. The key intermediate in this synthesis is the bicyclic azoene Ts-9, and the key step is the regio- and stereoselective conjugate addition of the chiral arylcopper compound Cu-8d/P-n-Bu3 to the azoene with formation of hydrazone 7d. Enantioselective synthesis of azoene Ts-9 of 95% ee from ketone 4 was accomplished in four and five steps, respectively. Thus, enantioselective deprotonation of bicyclic ketone 4 with chiral base Li-10 and trapping of lithium enolate 11 with ClSiMe3 gave enol ether 12, which was chlorinated with N-chlorosuccinimide (NCS) to afford chloro ketone 13. Alternatively, chloro ketone 13 was also prepared upon chlorination of 11 with NCS. Chloro ketone 13 was converted to chloro hydrazone 14, which upon treatment with a mild base furnished azoene Ts-9. Arylcopper compound 8d of...

Journal ArticleDOI
TL;DR: In this paper, the mixed dicyclopentadienyl titanium compound Ti(η5-C5Me5)(C5H5)Cl2 with LiN(H)NCPh2, in toluene at −78 °C, gives the hydrazonide(1−) derivatives (metalloazine) Ti(∆5C5me5) Cl2 with NEt3 in the presence of one equivalent of NEt 3.

Journal ArticleDOI
TL;DR: The masked aldehyde amino acid Fmoc-Hyl(Boc-oxazolidine) 1, has been synthesized from the parent amino acid in five steps (3 pots) as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this paper, an efficient asymmetric synthesis of α-trifluoromethylated homoallylamine via nucleophilic allylation of trifluoroacetaldehyde SAMP- or RAMP-hydrazone, followed by benzoylation and SmI 2 -promoted nitrogen-nitrogen single bond cleavage is described.
Abstract: An efficient asymmetric synthesis of both enantiomers of α-trifluoromethylated homoallylamine via nucleophilic allylation of trifluoroacetaldehyde SAMP- or RAMP-hydrazone, followed by benzoylation and SmI 2 -promoted nitrogen-nitrogen single bond cleavage is described.

Journal ArticleDOI
TL;DR: In this article, a flexible asymmetric synthesis of 2-substituted piperidin-3-ols was achieved, starting from a protected glycol aldehyde hydrazone.
Abstract: Starting from a protected glycol aldehyde hydrazone a flexible asymmetric synthesis of 2-substituted piperidin-3-ols was achieved. An α-alkylation/1,2-addition sequence furnished the intermediate hydrazines which were subjected to reductive cleavage of the chiral auxiliary. After acidic workup and simultaneous deprotection the title compounds were obtained in moderate overall yields and excellent diastereomeric and enantiomeric excesses (de, ee >96%) by ring closure under reductive amination conditions.

Journal ArticleDOI
01 Nov 2002-Synlett
TL;DR: In this paper, the preparation and application of three new solid supports with piperazine-derived hydrazine anchoring groups are described, which are used for immobilization of ketones.
Abstract: The preparation and application of three new solid supports with piperazine-derived hydrazine anchoring groups are described. The supports were used for immobilization of ketones. The ketones: cyclohexanone, 4-tert-butylcyclohexanone, 3-pentanone and tropinone, which were bound to polymers in the form of their hydrazones, were deprotonated with LDA and alkylated with propyl iodide or benzyl bromide. The resulting alkylated products were cleaved off the solid support on treatment with trifluoroacetic acid in dichloromethane. Linkers with 6- and 3-carbon atom spacers gave better results than the simple N-aminopiperazine linker.

Journal ArticleDOI
TL;DR: In this article, an efficient, regio-and enanti-lective synthesis of α-substituted β-amino ketones has been developed using the SAMP/RAMP hydrazone methodology.
Abstract: An efficient, regio- and enantioselective synthesis of α-substituted β-amino ketones has been developed. Starting from simple ketones, enantiomerically pure α-silyl ketones la-j were prepared employing the SAMP/RAMP hydrazone methodology. The cyclic α-silyl ketones 1a-e were selectively converted to the silyl enol ethers (Z)-2a-e, whereas the cyclic α-silyl ketones 1f-j were obtained exclusively as the silyl enol ethers (E)-2f-j. In all cases the yields were virtually quantitative. Diastereoselective α-silyl controlled Mannich reaction with BF 3 .Et 2 O activated N,N-dibenzyl-N-methoxymethylamine afforded the α'-substituted β-amino ketones 3a-j in high yields (93-96%) and in one case good otherwise excellent diastereoselectivities (de 65, ≥96%). The configuration of the new stereogenic center follows from mechanistic considerations and was unambigously determined by NOE experiments with the major diastereoisomer (S,R)-3g and by X-ray crystal structure analysis of compound (S,R)-3c. Finally, the silyl group was removed with NH 4 F-Bu 4 NF in high yields (89-99%). The acyclic α-substituted β-amino ketones 4a-e were achieved in excellent enantiomeric excesses (ce 93-≥96%). During removal of the silyl group of the cyclic α-substituted β-amino ketones 4f-j racemisation could not be totally avoided (ce 32-89%).

Journal ArticleDOI
TL;DR: Two homogeneous series of homodimetallic iron(II) hydrazone complexes of general formula [CpFe(η6p-RC6H4)−NHNCH−( η5-C5H4)-FeCp]+PF6− as mentioned in this paper have been prepared and stereoselectively obtained as their trans isomers about the NC double bond by reaction of the corresponding organometallic hydrazines.
Abstract: Two homogeneous series of homodimetallic iron(II) hydrazone complexes of general formula [CpFe(η6-p-RC6H4)–NHNCH–(η5-C5H4)FeCp]+PF6− (Cp=η5-C5H5): R=H, [5]+PF6−; Me, [6]+PF6−; MeO, [7]+PF6−; Cl, [8]+PF6−; and [CpFe(η6-p-RC6H4)–NHNCMe–(η5-C5H4)FeCp]+PF6−: R=H, [9]+PF6−; Me, [10]+PF6−; MeO, [11]+PF6−, have been prepared. These hydrazones were stereoselectively obtained as their trans isomers about the NC double bond, by reaction of the corresponding organometallic hydrazines [CpFe(η6-p-RC6H4NHNH2)]+PF6−, R=H, [1]+PF6−; Me, [2]+PF6−; MeO, [3]+PF6−; and Cl, [4]+PF6−, with formylferrocene, CpFe(η5-C5H4–CHO), and acetylferrocene, CpFe(η5-C5H4–CO-Me), respectively. All the new compounds were characterized by elemental analysis and IR, UV-Vis and 1H NMR spectroscopies. For compound [9]+PF6−, the activation energy ΔG# for the hindered rotations of the mixed sandwich [CpFe(η6-C6H5–)]+ (41.8±0.9 and 41.2±3.7 kJ mol−1) and the ferrocenyl unit (40.0±3.2 kJ mol−1) about the –NH–NCMe– hydrazone backbone have been determined by variable temperature 1H NMR spectroscopic studies. The electrochemical behavior of the dinuclear hydrazones was explored by cyclic voltammetry, and features the role of the cationic [CpFe(η6-arene)]+ moiety as an electron acceptor. The crystalline and molecular structure of [9]+PF6− was determined by single crystal X-ray crystallographic analysis. The structure shows the presence of both syn and anti rotamers in the asymmetric unit. The analysis of the electronic structure of [9]+ through DFT calculations indicate a strong perturbation of the metal centers by the hydrazone bridge as well as some metal-metal interaction through the bridge.

Journal ArticleDOI
TL;DR: A series of peptidyl hydrazones was synthesized, and their inhibitory activity against mu-calpain and water-solubility were measured, and N,N-dimethyl glycyl hydrazone 6 was found to possess the excellent in vitro metabolic stability.

Journal ArticleDOI
01 Jan 2002-Steroids
TL;DR: The hypothesis that an intramolecular 1,5-hydride shift mechanism promotes complete conversion of 1 to 2 under classical Wolff-Kishner reduction conditions is supported.

Journal ArticleDOI
TL;DR: A novel Schiff base compound, N-(1-phenyl-3-methyl-4-benzal-pyrazolone-5)-salicylidene hydrazine (PMBP-SAH), has been synthesized and characterized by X-ray diffraction as discussed by the authors.
Abstract: A novel Schiff base compound, N-(1-phenyl-3-methyl-4-benzal-pyrazolone-5)-salicylidene hydrazine (PMBP-SAH), has been synthesized and characterized by X-ray diffraction: monoclinic, space group C2/c with a = 21.796(5) A, b = 18.370(3) A, c = 20.843(3) A, β = 95.440(10)°, V = 8308(3) A3, and Z = 16. The title compound contains two kinds of tautomers: the red compound is the keto form and the other is the enol form. Changes in color are due to the isomerization of the enol and keto forms by the intramolecular proton transfer.

Journal ArticleDOI
TL;DR: In this paper, two 2,4-dinitrophenylhydrazones were prepared and their X-ray crystal structures determined, and they were found to be internally stabilized by a weak intramolecular interaction between nitrogen and boron from within a five-membered ring.
Abstract: Under conditions that typically afford bicyclic boron heterocycles directly, (2-formylphenyl)boronic acids react with 2,4-dinitrophenylhydrazine in ethanol to give highly water-resistant diethyl boronate esters. Two such 2,4-dinitrophenylhydrazones were prepared and their X-ray crystal structures determined. Contrary to a previous suggestion that their unusual stability is due to an intramolecular N→B coordination giving a six-membered BN 2 C 3 ring system based on a (Z)-hydrazone, these compounds instead were found to be (E)-hydrazones internally stabilized by a weak intramolecular interaction between nitrogen and boron from within a five-membered ring. Further study revealed that the electron deficiency of the starting hydrazine reagent plays a key role in determining the structure of the hydrazone isolated, and that the water-resistant boronate esters can be hydrolyzed under forcing conditions to the boronic acids.