Cyclic Phenylboronates of Ecdysteroids as Products of Regiospecific Reaction with Phenylboronic Acid

1993 ◽  
Vol 58 (3) ◽  
pp. 612-618 ◽  
Author(s):  
Jaroslav Píš ◽  
Jiří Hykl ◽  
Miloš Buděšínský ◽  
Juraj Harmatha
Keyword(s):  
Aqueous Solutions ◽  
Carboxylic Acids ◽  
Nmr Spectra ◽  
Phenylboronic Acid ◽  
Side Chain ◽  
Reaction Conditions ◽  
Cyclic Esters ◽  
H Nmr ◽  
High Yields

The diol system in the side-chain of ecdysteroids reacts with phenylboronic acid under formation of cyclic esters. Phenylboronates of ecdysteroids I - V were prepared. The regiospecific reaction course was confirmed by 1H NMR spectra of the products. The reaction conditions were studied for 20-hydroxyecdysone (I). The phenylboronate can be prepared in high yields even in aqueous solutions. The liberation of the ecdysteroid I from the corresponding phenylboronate VI was performed using various reagents - diols or carboxylic acids.

E-Homolupane Derivatives Substituted in Position 17 and 22a. 1H NMR, 13C NMR and IR Spectra

1995 ◽  
Vol 60 (4) ◽  
pp. 619-635 ◽  
Author(s):  
Václav Křeček ◽  
Stanislav Hilgard ◽  
Miloš Buděšínský ◽  
Alois Vystrčil
Keyword(s):  
Nmr Spectra ◽  
2D Nmr ◽  
Coupling Constants ◽  
Side Chain ◽  
Oxidation Reactions ◽  
H Nmr ◽  
Complete Assignment ◽  
Nmr Techniques ◽  
Intramolecular Association ◽  
C Nmr

A series of derivatives with various oxygen functionalities in positions 17,22a or 19,20 was prepared from diene I and olefin XVI by addition and oxidation reactions. The structure of the obtained compounds was confirmed by 1H NMR, 13C NMR and IR spectroscopy. The kind of intramolecular association of the 17α-hydroxy group was studied in connection with modification of the side chain and substitution in position 22a. Complete assignment of the hydrogen signals and most of the coupling constants was accomplished using a combination of 1D and 2D NMR techniques. The 1H and 13C NMR spectra are discussed.

sHigh resolution 1H nuclear magnetic resonance studies of a flavine and its product with MoCl4

1977 ◽  
Vol 55 (4) ◽  
pp. 575-582 ◽  
Author(s):  
T. Roberie ◽  
N. S. Bhacca ◽  
J. Selbin
Keyword(s):  
Aqueous Solution ◽  
Nuclear Magnetic Resonance ◽  
Binding Sites ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Side Chain ◽  
Magnetic Resonance Studies ◽  
H Nmr ◽  
Metal Atoms ◽  
1H Nuclear Magnetic Resonance

The high resolution 1H nmr spectra of the substituted flavine, 3-N-methyltetraacetylriboflavine (3-Me-TARF), and its non-aqueous solution complexes with Gd(fod)3, Eu(fod)3, MoCl4, and MoCl4•2CH3(CH2)2CN, were studied in order to try to discern the binding sites of the flavine as it attaches to the molybdenum. Evidence was found that all three metal atoms, Gd(III), Eu(III), and Mo(IV), are attached in solution not only by the primary binding (chelating) sites of the flavine, viz., the O-4 and N-5 atoms, but also by an acetyl oxygen atom, at the C-4′ site of the ribityl side chain. 300 MHz spectra of the 3-Me-TARF have permitted the coupling constants for the side chain methine and methylene protons to be obtained.

scholarly journals Tyrosinase enzyme mediated: Synthesis and larvicidal activity of 1,5-diphenyl pent-4-en-1-one derivatives against Culex quinquefasciatus and investigation of Ichthyotoxicity against O. mossambicus

2021 ◽  
Author(s):  
SathishKumar Chidambaram ◽  
Daoud Ali ◽  
Saud Alarifi ◽  
Surendra Kumar Radhakrishnan ◽  
Idhayadhulla Akbar
Keyword(s):  
Larvicidal Activity ◽  
Culex Quinquefasciatus ◽  
Oreochromis Mossambicus ◽  
Docking Studies ◽  
Reaction Conditions ◽  
Mass Spectral ◽  
H Nmr ◽  
Tyrosinase Enzyme ◽  
High Yields ◽  
C Nmr

Abstract Larvicidal activity of 1,5-diphenylpent-4-en-1-one derivatives were synthesized via grindstone method, tyrosinase enzyme used as a catalyst of this process. This method offers high yields with mild reaction conditions. Synthesized compounds were conformed from FTIR, 1H NMR, 13C NMR, mass spectral and elemental analysis. In this study, a total of 17 compounds (1a–1q) were synthesized, and their larvicidal and antifeedant activities were evaluated. Compound 1i (1-(5-oxo-1,5-diphenylpent-1-en-3-yl)-3-(3-phenylallylidene)thiourea) was extremely active (LD50: 12.09 µg/mL) against Culex quinquefasciatus compared with temephos and permethrin, whereas compounds 1i at 100 µg/mL generated 0% mortality within 24h against Oreochromis mossambicus in an antifeedant screening, and Ichthyotoxicity was determined as the death ratio (%) at 24 h. The compounds 1a, 1e, 1f, 1j, and 1k were found to be highly toxic whereas the 1i was not toxic in antifeedant screening. Therefore, 1i was found to have a high larvicidal activity against C. quinquefasciatus, and was non-toxic to non-target aquatic species. Molecular docking studies also supported the finding that 1i is a potent larvicide with more binding energy than the control (-10.0 vs. -7.6 Kcal/mol) in the 3OGN protein. The lead molecule is very important to larvicidal properties and insecticides.

Analysis of 1H-NMR spectra of cinnamaldehyde type model substances of lignin

1980 ◽  
Vol 45 (2) ◽  
pp. 330-334 ◽  
Author(s):  
Tibor Liptaj ◽  
Milan Remko ◽  
Ján Polčin
Keyword(s):  
Double Bond ◽  
Nmr Spectra ◽  
Side Chain ◽  
Type Model ◽  
Stable Conformer ◽  
Spectra Analysis ◽  
H Nmr ◽  
Nmr Data ◽  
Lignin Model ◽  
Model Substances

1H-NMR spectra of the following lignin model substances have been analyzed: cinnamaldehyde, 2-methoxycinnamaldehyde, 3-methoxycinnamaldehyde, 4-methoxycinnamaldehyde, 3,4-dimethoxycinnamaldehyde, 3-methoxy-4-hydroxycinnamaldehyde and 3,4,5-trimethoxycinnamaldehyde. From the NMR spectra analysis it follows that the studied compounds exist in solutions as trans isomers. Theoretical (PCILO) calculations in agreement with the NMR data have shown that the more stable conformer has trans orientation of C=O group with respect to the double bond of the conjugated side chain.

Enhanced the Negative Charges of Antheraea pernyi Silk Fibroin by Methylglyoxal Modification

2015 ◽  
Vol 1101 ◽  
pp. 307-313 ◽  
Author(s):  
Jing Li ◽  
Ceng Zhang ◽  
Yi Zhang ◽  
Yan Ni Yu ◽  
Jing Wan Luo ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Silk Fibroin ◽  
Nmr Spectra ◽  
Negative Charge ◽  
Controlled Drug Release ◽  
Side Chain ◽  
Antheraea Pernyi ◽  
H Nmr ◽  
Chemically Modified ◽  
Positively Charged

Antheraea pernyi silk fibroin has favorable biocompatibility, good bioactivity and controllable biodegradability, meeting the basic requirements of controlled drug release carriers. Enhancing the negative charge of silk fibroin could further increase the encapsulation and loading efficiency of positively charged drugs. In this study, Antheraea pernyi silk fibroin was chemically modified by methylglyoxal in aqueous solution. The electric charge properties of Antheraea pernyi silk fibroin were examined to characterize the modification, the results indicated that the isoelectric point of Antheraea pernyi silk fibroin decreased from 4.5 to 3.9, and the zeta potential reduced from-11.7 mV to-12.8 mV. Amino acid analysis and 1H-NMR spectra showed that arginine residue of Antheraea pernyi silk fibroin side chain was modified by methylglyoxal for enhancing negative charge of silk fibroin. These results suggested that methylglyoxal-modified Antheraea pernyi silk fibroin could be considered as a potential starting material in loading positively charged drugs.

scholarly journals SYNTHESIS OF SOME FLAVONES AND 4-THIOFLAVONES AS POTENT ANTIBACTERIAL AGENTS

2009 ◽  
Vol 12 (3) ◽  
pp. 33-39
Author(s):  
Ha Tuong Do ◽  
Dao Thanh Tran
Keyword(s):  
Dimethyl Sulfoxide ◽  
Potassium Hydroxide ◽  
Nmr Spectra ◽  
Room Temperature ◽  
Antibacterial Agents ◽  
Synthetic Compounds ◽  
H Nmr ◽  
High Yields ◽  
Benzaldehyde Derivatives ◽  
Boiling Toluene

A series of flavones and thioflavones were synthesized via the chalcone pathway, in which 2'-hydroxyacetophenone is condensed with benzaldehyde derivatives in the medium of potassium hydroxide - methanol at room temperature. The obtained chalcones were treated by iodine in refluxed dimethyl sulfoxide turning into the corresponding flavones. Reaction of flavones and Lawesson's reagent in boiling toluene gave the 4-thioflavones with high yields from 53-76%. All the synthetic compounds were purified by column chromatography and recorded their UV, IR and 'H-NMR spectra.

scholarly journals Triflic Anhydride Promoted Synthesis of Primary Amides and their Conversion into Nitriles

SynOpen ◽  
2018 ◽  
Vol 02 (02) ◽  
pp. 0180-0191
Author(s):  
Anil Rana ◽  
Varun Kumar ◽  
Lata Tiwari ◽  
Anamika Thakur ◽  
Chhuttan Meena ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Functional Group ◽  
Reaction Conditions ◽  
One Pot ◽  
Limited Success ◽  
High Yields

A facile, two-pot conversion of carboxylic acids into the corresponding nitriles has been developed using triflic anhydride as a promoter and aqueous NH4OH as a source of nitrogen. The methodology involves synthesis of primary amides from carboxylic acids as the key first step using triflic anhydride and aqueous NH4OH as a source of ­nitrogen. Triflic anhydride is also found to be an excellent reagent for conversion of primary amides into nitriles, affording high yields with considerable chemoselectivity and functional group tolerance. In spite of the mild reaction conditions and broad substrate scope for the two-step conversions, all attempts for one-pot domino conversion of acids into nitriles exhibited limited success because of poor yields.

Derivatives of 5α-androstan-3α- and 3β-ol with acrylonitrile side chain

1991 ◽  
Vol 56 (12) ◽  
pp. 2906-2916 ◽  
Author(s):  
Vladimír Pouzar ◽  
Hana Chodounská ◽  
Ivan Černý ◽  
Pavel Drašar
Keyword(s):  
Double Bond ◽  
Nmr Spectra ◽  
Sodium Hydride ◽  
Coupling Constants ◽  
Side Chain ◽  
H Nmr ◽  
Derivatives Of

Aldehydes II - III were reacted with diethyl cyanomethylphosphonate and sodium hydride in 1,2-dimethoxyethane to give the respective pairs of unsaturated nitriles IVa and Va, VIa and VIIa, and VIIIa and IXa differing in configuration at the 20(21)-double bond. The pure isomers were obtained by chromatography on alumina, and the configuration at the double bond in them has been established on the basis of the coupling constants J(20, 21) in their 1H NMR spectra. Nitriles IVa - VIIa and IXa were converted via the corresponding hydroxy derivatives into hemisuccinates IVd - VIId and IXd, and into β-D-glucosides IVe - VIIe and IXe.

scholarly journals Silver(I) as a widely applicable, homogeneous catalyst for aerobic oxidation of aldehydes toward carboxylic acids in water—“silver mirror”: From stoichiometric to catalytic

2015 ◽  
Vol 1 (2) ◽  
pp. e1500020 ◽  
Author(s):  
Mingxin Liu ◽  
Haining Wang ◽  
Huiying Zeng ◽  
Chao-Jun Li
Keyword(s):  
Natural Products ◽  
Carboxylic Acids ◽  
Atmospheric Oxygen ◽  
Aerobic Oxidation ◽  
Aromatic Aldehydes ◽  
Catalyst Loading ◽  
Homogeneous Catalyst ◽  
Reaction Conditions ◽  
Silver Mirror ◽  
High Yields

The first example of a homogeneous silver(I)-catalyzed aerobic oxidation of aldehydes in water is reported. More than 50 examples of different aliphatic and aromatic aldehydes, including natural products, were tested, and all of them successfully underwent aerobic oxidation to give the corresponding carboxylic acids in extremely high yields. The reaction conditions are very mild and greener, requiring only a very low silver(I) catalyst loading, using atmospheric oxygen as the oxidant and water as the solvent, and allowing gram-scale oxidation with only 2 mg of our catalyst. Chromatography is completely unnecessary for purification in most cases.

The direct electrochemical synthesis of phenylselenolato complexes of some main group and late transition elements

1989 ◽  
Vol 67 (1) ◽  
pp. 127-129 ◽  
Author(s):  
Rajesh Kumar ◽  
Dennis G. Tuck
Keyword(s):  
Aqueous Solutions ◽  
Electrochemical Synthesis ◽  
Nmr Spectra ◽  
Electrochemical Cell ◽  
Main Group ◽  
Diphenyl Diselenide ◽  
Transition Elements ◽  
Late Transition Metals ◽  
Late Transition ◽  
High Yields

The electrochemical oxidation of anodes of selected Main Group or late transition metals (M) in non-aqueous solutions of diphenyl diselenide gives the corresponding M(SePh)n compounds in high yields (M = Zn, Cd, n = 2; M = Cu, Ag, Tl, n = 1; M = Sn, n = 4). The addition of either 1,10-phenanthroline or triphenylphosphine to the electrochemical cell yields adducts in the case of cadmium and copper. The 77Se nmr spectra have been recorded. Keywords: electrochemistry, synthesis, phenylselenates, 77Se nmr spectra.

Sign in / Sign up

Export Citation Format

Share Document