Benzyl Carbazate Research Articles

Stable Ditriflates of D‐Glucose in the Synthesis of Iminosugars and Polyhydroxylated Pipecolic Acids

AbstractA synthesis of the five membered iminosugar DAB and a divergent synthesis of the six membered iminosugar 1‐dehydromannojirimycin (DMJ) and the corresponding sugar imino acid are reported. They involve double nucleophilic displacements of a D‐xylose ditriflate by benzyl carbazate and a D‐glucose ditriflate by allyl amine, respectively. They are followed by a similar protocol consisting of hydrolysis and oxidation or reduction of the resulting bicyclic glycosides. This allowed DMJ to be obtained from the cheap sugar D‐glucose.

Syntheses and crystal structures of benzyl N'-[(E)-2-hydroxybenzylidene]hydrazinecarboxylate and benzyl N'-[(E)-5-bromo-2-hydroxybenzylidene]hydrazinecarboxylate.

Benzyl N'-[(E)-2-hydroxybenzylidene]hydrazinecarboxylate, C15H14N2O3 (I) and benzyl N'-[(E)-5-bromo-2-hydroxybenzylidene]hydrazinecarboxylate (II), C15H13BrN2O3, have been synthesized by the reaction of either 2-hy-droxy-benzaldehyde or 5-bromo-2-hy-droxy-benzaldehyde with benzyl carbazate, respectively. Both the compounds crystallize in the monoclinic crystal system with space groups Pn (Z' = 1, I) and P21/c (Z' = 2, II). Mol-ecular conformations in each structure are similar, and both structures feature strong intra-molecular O-H⋯N hydrogen bonds, which form S(6) ring motifs. There are also strong N-H⋯O and weak C-H⋯O hydrogen bonds in both structures, but their modes of packing within their respective crystals are markedly different. Some comparisons are made with the structures of a few related compounds.

Effect of Salt (Sodium Chloride) Replacement With Potassium Chloride, High Pressure Processing, and Cold Storage at 4°C on Beef Sausage Volatile Compounds.

This study aimed to investigate the partial substitution of 0, 25 and 50% sodium chloride (NaCl) by potassium chloride (KCl) coupled with high-pressure processing (HPP) effects on volatile compounds and lipid oxidation of beef sausage at five (0, 3, 7, 14, and 21) different cold storage days (4°C). The odor activity values (OAV) of the various compounds were visualized by heat map analysis. Thiobarbituric acid reactive substances (TBARS) of the samples treated with 100% NaCl and HPP increased by an average of 0.52 ± 0.01 mg MDA/kg compared with the control (100% NaCl-no HPP) across the 21 storage days. In addition, 50% NaCl substitution with KCl in combinations with HPP treatments increased TBARS across the 21 storage days by an average of 0.40 ± 0.02 mg MDA/kg compared with no HPP treatment. However, on day 3, there was a sharp decrease in TBARS by an average of 0.10 ± 0.01 mg MDA/kg compared with days 0, 7, 14, and 21 in all treatments. At the end of 21 days of storage, a total of 227 volatile compounds were identified and quantified in the beef sausage, including 43 aldehydes, 46 phenols, 8 ketones, 30 alcohols, 14 acids, 12 esters, 27 terpenes, and 47 alkanes. However, no ketone compounds were detected on days 7, 14 and 21; esters on day 14 and acids on days 14 and 21 in the samples treated with or without HPP across the salts levels. However, high OAVs (OAV > 1) were obtained after partial substitution of NaCl with KCl at 25 and 50% with HPP treatment compared to the samples not treated with HPP. The aroma perceived in the beef sausage was due to compounds with the highest OAVs such as; pentadecanal, benzyl carbazate, anethole, myristicin, o-cresol, phenylacetaldehyde and (E)-methyl isoeugenol, pentadecanal, hexanoic acid, octanoic acid, eugenol, trans-2-nonenal, trans-2-octenal, trans-2-decenal, 2-butyl-1-octanol, 2,3-butanedione, ethyl hexanoate, ethyl octanoate, (-)-4-terpineol which had an OAV > 1 as compared to the other compounds with an OAV < 1. In conclusion, 25 and 50% NaCl partial replacement with KCl coupled with HPP technique can be considered in producing low-NaCl beef sausage in order to improve the flavor and decrease lipid oxidation during cold storage.

Bis[benzyl 2-(heptan-4-ylidene)hydrazine-1-carboxylate]bis(thiocyanato)cobalt(II)

The title compound, [Co(NCS)2(C15H22N2O2)2] or C32H44CoN6O4S2, was prepared from cobalt(II) nitrate, benzyl carbazate and ammonium thiocyanate in the presence of 4-heptanone. The compound crystallizes with two centrosymmetric complexes in which the cobalt(II) atoms have a trans-CoO2N4 octahedral coordination geometry. In the crystal, N—H...S, C—H...S and C—H....π contacts stack the complex molecules along the b-axis direction.

Synthesis, structural characterization, and thermal properties of monomeric (Mn, Co, Ni, and Zn) and polymeric (Cd) complexes of thiocyanates with benzyl carbazate as an ancillary ligand

Five complexes [M(NCS)2(bc)2] M = Mn (1), Co (2), Ni (3), Zn (4), and [Cd(NCS)2(bc)]n (5), (bc) = benzyl carbazate (benzyl hydrazinecarboxylate), have been synthesized and characterized by physico-chemical and spectroscopic methods. The crystal structures of all five complexes have been confirmed by X-ray structural analysis. These results confirm that 1–4 are isotypes, and all four are centrosymmetric, with two mutually trans N,O chelating (bc) ligands in equatorial positions and a pair of trans-thiocyanate anions in the axial positions. The cadmium complex (5) is a coordination polymer. The asymmetric unit contains a square planar CdN2OS core, in which the (bc) ligand adopts an N, O bidentate coordination mode together with N and S bound thiocyanato anions. Polymer expansion increases the coordination number to six with the N and S bound thiocyanate ligands linking two adjacent complexes. This expansion results in double layers of cadmium octahedra propagating along the c axis direction. The thermal analyses of these compounds show endothermic decomposition processes to give respective metal thiocyanates as intermediates. For the Mn, Co, Ni, and Zn compounds these intermediates decompose exothermically to form metal oxides, whereas the Cd complex forms cadmium sulfide as the end product.

A bifunctional sensor based on diarylethene for the colorimetric recognition of Cu2+ and fluorescence detection of Cd2.

A novel bifunctional sensor based on diarylethene with a benzyl carbazate unit was synthesized successfully. It not only served as a colorimetric sensor for the recognition of Cu2+ by showing changes in absorption spectra and solution color, but also acted as a fluorescent sensor for the detection of Cd2+ through obvious emission intensity enhancement and fluorescence color change. The sensor exhibited excellent selectivity and sensitivity towards Cu2+ and Cd2+, and the limits of detection for Cu2+ and Cd2+ were 8.36 × 10−8 mol L−1 and 1.71 × 10−7 mol L−1, respectively, which were much lower than those reported by the WHO and EPA in drinking water. Furthermore, its application in practical samples demonstrated that the sensor can be effectively applied for the detection of Cu2+ and Cd2+ in practical water samples.

Solvent assisted synthesis, structural characterization and biological evaluation of cobalt(II) and nickel(II) complexes of Schiff bases generated from benzyl carbazate and cyclic ketones

A series of mononuclear cobalt and nickel complexes of the types [M(NCS)2(L1)2], M = Co 1 or Ni 2, [M(NCS)2(L2)2]·nH2O, M = Co (n = 0) 3 or Ni (n = 2) 4 and [M(NCS)2(L3)2], M = Co 5 or Ni 6, where L1 = benzyl 2-(cyclobutanylidene)hydrazinecarboxylate, L2 = benzyl 2-(cyclopentanylidene)hydrazinecarboxylate and L3 = benzyl 2-(cyclohexanylidene)hydrazinecarboxylate, were synthesized by template reactions of the metal nitrates, ammonium thiocyanate and benzyl carbazate (bc) with cyclobutanone (cb), cyclopentanone (cp) or cyclohexanone (ch). These compounds have been characterized by elemental analysis, infrared, electronic absorption and 1H NMR spectroscopies, together with single crystal X-ray diffraction. Crystal structures of the complexes 1, 3–6 showed that the Schiff base ligands coordinate to the metal ions via the azomethine nitrogen and carbonyl oxygen atoms. In each case the two thiocyanate ligands coordinate through their nitrogen atoms resulting in complexes with a six coordinate octahedral geometry. The thermal stability of the complexes was investigated by TG-DTA and all of the compounds (1–6) undergo endothermic followed by exothermic decomposition processes to form the respective metal oxides. The antibacterial activity of the cobalt(II) and nickel(II) complexes was examined against Gram positive and Gram negative bacteria at concentrations between 40 and 80 μg mL−1. The binding interaction of human serum albumin (HSA) with compounds 1–6 was explored by multi-spectroscopic techniques and docking studies revealed the complexes bind to HSA through hydrophobic interactions. The cytotoxic activity of all of the compounds was evaluated against the K-562 (leukemia cell line) by MTT assays and, remarkably, all of the complexes were found to show good activity towards this cancer cell line. DAPI (4′,6-diamidino-2-phenylindole) staining assay further confirmed that complexes induced leukemia cancer cell death by an apoptosis mechanism.

Syntheses, structural diversity and thermal behavior of first row transition metal complexes containing potential multidentate ligands based on 2,6-diacetylpyridine and benzyl carbazate

The Schiff base ligand, N′-(1-{6-[1-(Benzyloxycarbonyl-hydrazono)-ethyl]-pyridin-2-yl}-ethylidene)-hydrazinecarboxylic acid benzyl ester (bc2-dap), was synthesized by the reaction of 2,6-diacetylpyridine (dap) with benzyl carbazate (bc) in methanol. Also first row transition metal complexes of the general formula [M(NCS)2(bc2-dap)]·nH2O; M = Mn (1), Fe (2), Co (3), Zn (4) or Co (5); n = 0 (1–4) and n = 1 (5), [Fe(bc2-dap)(H2O)2]·2Cl·4H2O (6), [Ni(NCS)2(bc2-dap)]·CH3OH (7) and [Co(NCS)2(bc-dap)] (8) have been synthesized using a template method and characterized by spectroscopic techniques and single crystal X-ray diffraction. Complexes 1–4 are isotypic, while compounds 1–6 comprises of discrete mononuclear units with pentagonal bipyramidal geometry. In contrast compounds 7 and 8 adopt octahedral and tetrahedral geometries, respectively. In all of the complexes 1–6, the Schiff base acts as a pentadentate ligand that binds via the pyridine nitrogen, azomethine nitrogen and carbonyl oxygen atoms. The Schiff base ligand occupies the equatorial plane and isothiocyanate anions for 1–5 and water molecules for 6 occupy the axial positions. Compound 7 has octahedral geometry in which the Schiff base ligand acts as a tetradentate ligand and in this case one of the carbonyl oxygen atoms is not involved in coordination. Furthermore, the N-bound isothiocyanate anions are coordinated as terminal ligands. In compound 8, the Schiff base behaves as a bidentate ligand through the azomethine nitrogen and pyridine nitrogen atoms leading to a tetrahedral geometry with the remaining two sites are occupied by isothiocyanate ions. Thermal reactivity of the ligand and complexes (1–8) was studied by TG-DTA and the complexes all undergo endo- followed by exothermic decomposition to give metal oxides, whereas the ligand decomposes completely to give gaseous products.

Template synthesis, structural variation, thermal behavior and antimicrobial screening of Mn(II), Co(II) and Ni(II) complexes of Schiff base ligands derived from benzyl carbazate and three isomers of acetylpyridine

Complexes of Mn(II), Co(II) and Ni(II) with ligands derived from the condensation of benzyl carbazate with three stereoisomers of acetylpyridine have been synthesized using a template method. The complexes have the compositions [Ni(bc-2ap)2] (1), [M(NCS)2(bc-3ap)2(bc)]·H2O; M=Co (2) or Ni (3), [Mn(NCS)2(bc-3ap)4]·2CH3OH (4), [M(NCS)2(bc-3ap)4]·2H2O; M=Co (5) or Ni (6) and [M(NCS)2(bc-4ap)2(CH3OH)2]; M=Mn (7) or Co (8) [where bc=benzyl carbazate, 2ap, 3ap and 4ap=2-, 3- and 4-acetylpyridine]. Characterization of the products involved elemental analysis, IR, UV–vis and 1H NMR, and in the case of 1, 2, 4, 5 and 8 single crystal X-ray structures have been determined. These are all six coordinate with octahedral coordination geometries. Compound 1 is unique with the 2-acetylpyridine ligand undergoing enolisation and deprotonation with two of the uninegative ligands coordinating to the Ni(II) cation in a tridentate chelate fashion. For 2 to 8 the charges of the M(II) cations are balanced in each case by two thiocyanato ligands, mutually cis for 2 and 3 but trans for 4–8. In these latter six-coordinate complexes, 2–8, the benzyl carbazate derived Schiff base ligands bind to the metal atoms in a trans monodentate fashion via the pyridine N atoms, two for 2, 3, 7 and 8 and four such ligands for 4, 5 and 6. In addition to the thiocyanato anions, the remaining coordination positions are filled by bidentate chelate carbazate molecules for 2 and 3, and two trans oriented methanol molecules for 7 and 8. Thermal reactivity of the complexes was studied by TG-DTA. In addition, antimicrobial screening confirmed that all of the complexes, except 1, have a moderate to good range of activity against both Gram-positive and Gram-negative bacterial strains and also against fungi.

New Schiff bases derived from benzyl carbazate with alkyl and heteroaryl ketones

The condensation reaction of benzyl carbazate with the ketones, viz., dimethylketone, dipropylketone, cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone, 2-acetylpyridine, 3-acetylpyridine and 4-acetylpyridine, yielded the Schiff bases [benzyl 2-(propan-2-ylidene)hydrazinecarboxylate (1), benzyl 2-(heptan-4-ylidene)hydrazinecarboxylate (2), benzyl 2-(cyclobutanylidene)hydrazinecarboxylate (3), benzyl 2-(cyclopentnylidene)hydrazinecarboxylate (4), benzyl 2-(cyclohexanylidene)hydrazinecarboxylate (5), benzyl 2-(cycloheptanylidene)hydrazinecarboxylate (6), benzyl 2-(1-(pyridine-2-yl) ethylidene)hydrazinecarboxylate (7), benzyl 2-(1-(pyridine-3-yl) ethylidene)hydrazinecarboxylate (8) and benzyl 2-(1-(pyridine-4-yl) ethylidene)hydrazinecarboxylate (9)], respectively. These were all characterized by elemental analysis, FT-IR and NMR (1H and 13C) spectroscopic methods, and in addition, the structures of compounds 4, 8 and 9 have been confirmed by single-crystal X-ray diffraction studies, and their crystal structures are shown to be stabilized by hydrogen bonding. The thermal properties of all the Schiff bases have been studied in air and all of them underwent melting followed by endo- and exothermic decomposition processes to yield an ethanimine (CH3–CH=NH) intermediate which in turn decomposes exothermically to give gaseous products. In a nitrogen atmosphere, these compounds also show similar thermal behavior but with the absence of an intermediate. A docking study of compounds 2, 4 and 9 with human BChE provides useful structural information on their inhibition properties.

New cobalt(II) and nickel(II) complexes of benzyl carbazate Schiff bases: Syntheses, crystal structures, in vitro DNA and HSA binding studies

In the present study, new Schiff base complexes with the composition [M(NCS)2(L1)2]·nH2O, where M=Co (n=0) (1) and Ni (n=2) (2); [M(NCS)2(L2)2], M=Co (3) and Ni (4) as well as [M(NCS)2(L3)2], M=Co (5) and Ni (6); (L1=benzyl 2-(propan-2-ylidene)hydrazinecarboxylate, L2=benzyl 2-(butan-2-ylidene)hydrazinecarboxylate and L3=benzyl 2-(pentan-3-ylidene)hydrazinecarboxylate) have been synthesized by a template method. The complexes were characterised by analytical methods, spectroscopic studies, thermal and X-ray diffraction techniques. The structures of all the complexes explore that the metal(II) cation has a trans-planar coordination environment, the monomeric units containing a six-coordinated metal center in octahedral geometry with N-bound isothiocyanate anions coordinated as terminal ligands. Furthermore, the binding of the two Schiff base ligands to the metal centers involves the azomethine nitrogen and the carbonyl oxygen in mutually trans configuration. The binding interactions of all the complexes with Calf thymus-deoxyribonucleic acid (CT-DNA) and human serum albumin (HSA) have been investigated using absorption and emission spectral techniques. The CT-DNA binding properties of these complexes reveal that they bind to CT-DNA through a partial intercalation mode and the binding constant values were calculated using the absorption and emission spectral data. The binding constant values (~10×106moldm−3) indicate strong binding of metal complexes with CT-DNA. HSA binding interaction studies showed that the cobalt and nickel complexes can quench the intrinsic fluorescence of HSA through static quenching process. Also, molecular docking studies were supported out to apprehend the binding interactions of these complexes with DNA and HSA which offer new understandings into the experimental model observations.

Platinum(II) complexes with carbazates and hydrazides: Synthesis, spectral characterization, computational modeling, and biological studies

This work reports on the synthesis and characterization of complexes of the type cis-[Pt(L)2X2], where L=4-methoxybenzylcarbazate (4-MC), benzyl carbazate (BC), 4-fluorophenoxyacetic acid hydrazide (4-FH), 3-methoxybenzoic acid hydrazide (3-MH), ethyl carbazate (EC), tert-butyl carbazate (TC), (4-hydroxy-phenyl)-acetic acid hydrazide (4-HH), and X=Cl− or I−. The structures of the platinum(II) complexes were optimized and theoretical data show good agreement with the experimental results, suggesting that the ligands are coordinated via the NH2 groups. The cytotoxic activity of three representative compounds was evaluated in a chronic myelogenous leukemia cell line and health cell line from mouse (L929). The platinum complex with 4-fluorophenoxyacetic acid hydrazide was more active than the free ligand and carboplatin therefore it may be considered a promising antitumor agent. In addition, the platinum complexes with 4-methoxybenzylcarbazate (4-MC) and benzyl carbazate (BC) exhibited good activity. On the other hand, microbiological assays against Mycobacterium tuberculosis showed that all complexes and organic compounds are not very active.

Spectroscopic characterization and molecular modeling of novel palladium(II) complexes with carbazates and hydrazides

Palladium(II) complexes of the type trans-[Pd(L)2Cl2], where L=4-methoxybenzylcarbazate (4-MC), benzyl carbazate (BC), 4-fluorophenoxyacetic acid hydrazide (4-FH), 3-methoxybenzoic acid hydrazide (3-MH), ethyl carbazate (EC) and tert-butyl carbazate (TC) were synthesized by the slow addition of the ligand to K2PdCl4 previously dissolved in water or ethanol. These complexes were characterized by elemental analyses, conductivity measurements, TG/DTA, FT-IR, mass spectrometric and NMR spectroscopy (solution and solid-state). All coordination compounds exhibit a square planar coordination geometry in which the palladium(II) ion coordinates to two nitrogen atoms and two chlorine atoms. The structures of the palladium(II) complexes were optimized and theoretical data show that the trans isomer is more stable, in accordance with the experimental data. Preliminary in vitro tests of some these new palladium complexes in a chronic myelogenous leukemia cell line (k562 cells) are also reported.

Analysis of sequence, structure of GAPDH of Leishmania donovani and its interactions

Drug resistance acquired by Leishmania donovani (Ldv) is a major problem in the treatment and control of visceral leishmaniasis (VL). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a major glycolytic enzyme has been targeted as is found in other protozoan which cause diseases like sleeping sickness. GAPDH gene of Ldv (AG83 strain) was amplified, sequenced, and modeled on the basis of crystal structure of Leishmania mexicana. The model of the Ldv GAPDH exhibited NAD-binding domain with Rossmann folding. Virtual screening of different experimentally proved compounds with the crystal and the modeled structures of GAPDH of Leishmania strains revealed diverse binding affinities of different compounds. Comparison of binding affinities (based on different programs) of compounds revealed that discovery studio v2.5 (Ligandfit) was able to predict the most hit compounds, the best hit compounds against GAPDH of Leishmania strains are hydrazine, vetrazine, and benzyl carbazate. It is predicted that patients suffering from both VL and cardiac disorders (atrial fibrillation) may benefit if they are treated with warfarin in conjunction with first-line antileishmanial therapies such as miltefosine and AmBisome.

Migration of an acyl group in the pyrazole system: synthesis of 1-acyl-3-hydroxy-1H-pyrazoles and related derivatives. A new preparation of N,N ′-diacylhydrazines

A new general method for the synthesis of 1-acyl-3-hydroxy-1H-pyrazoles 5a–f and related derivatives 5g–i starting from 4-ethoxymethylene-2-phenyloxazol-5(4H)-one (1) and hydrazides, 4-phenylsemicarbazide, 4-phenylthiosemicarbazide and benzyl carbazate in boiling dioxane is described. The method includes a migration of an acyl or related unit. The X-ray study and NMR spectroscopic examination confirmed the structure of the products. A one-pot synthesis of N,N′-diacylhydrazines from hydrazides by the assistance of oxazolone 1 is also presented.

ChemInform Abstract: Organic Phosphorus Compounds. Part 84. Synthesis, Properties, and Biological Activity of Hydrazinomethylphosphonic and ‐phosphinic Acids and Derivatives.

AbstractBenzyl carbazate (I) reacts with formaldehyde (II) to yield N‐methylene benzyl carbazate (III) which is coupled with diethyl phosphite (IV) to give the hydrazinomethylphosphonate (V).

Synthesis of 5′-O-Aminothymidine and 5′-Deoxy-5′-Hydrazinothymidine, Novel Nucleoside Derivatives

Abstract Two novel nucleoside derivatives,5′-0-aminothymidine and 5′-deoxy-5′-hydrazinothymidine were synthesised as potential thymidine kinase inhibitors. The former was made from N-hydroxyu re thane and 5′-0-tosylthymidine and the latter from benzyl carbazate and 5′-0-tosylthymidine.