Tetrahydropyranyl (THP), methoxymethyl (MOM), and benzyloxymethyl (BOM) phenyl/alkyl ethers were efficiently cleaved to the corresponding parent hydroxyl compounds in good yields using catalytic amounts of Ce(SO4)2·4H2O by microwave-assisted or conventional heating in methanol solution. Intramolecular and competitive experiments demonstrated the chemoselective deprotection of THP ethers in the presence of triisopropylsilyl (TIPS) and tert-butyldiphenylsilyl (TBDPS) phenyl ethers. 相似文献
This report describes a synthesis of two potent impurities of repaglinide, benzyl repaglinide 1 and repaglinide isomer 2, from commercially available raw materials: 2-fluoro benzonitrile, (S)-3-methyl-1-[2-(piperidin-1-yl)phenyl]butylamine (5), and 3-ethoxy-[4-(ethoxycarbonyl)phenyl]acetic acid (7). These impurities are the crucial components in determining the quality of the drug substance, repaglinide, during its manufacturing. 相似文献
AbstractThirteen novel cyclic phosphates were rationally designed and synthesized by introducing diary ethers containing pyrimidine. All the target compounds were characterized by 1H, 13C, 31P NMR and HRMS. The test of herbicidal activity indicated that most of the compounds showed good herbicidal activities against Amaranthus retroflexus. The compounds IA-2 (1-(5,5-dimethyl-2-oxido-1,3,2-dioxaphosphinan-2-yl)propyl-2-((4,6-dimethoxypyrimidin-2-yl)oxy)benzoate) and IA-3 ((5,5-dimethyl-2-oxido-1,3,2-dioxaphosphinan-2-yl)(phenyl)methyl-2-((4,6-dimethoxypyrimidin-2-yl)oxy)benzoate) exhibited remarkable post-emergency herbicidal activity against the tested monocotyledonous weed at the dosage of 112.5?g ai/ha. 相似文献
Abstract Vardenafil hydrochloride trihydrate (Levitra) is used to treat erectile dysfunction (ED) and is an inhibitor of phosphodiesterase type 5 (PDE-5) enzyme. It maintains higher levels of cyclic guanosine monophosphate (cGMP), relaxes smooth muscles, promotes penile blood flow, and enhances erectile function. During the bulk drug synthesis of vardenafil hydrochloride trihydrate, six related substances (impurities), vardenafil dimer, vardenafil N-oxide, vardenafil glycene, vardenafil oxopiperazine, vardenafil oxoacetic acid, and phenyl vardenafil were identified, and these are reported herein for the first time. The present work describes the synthesis and characterization of these impurities. 相似文献
Ring-substituted phenyl propenyl ethers were found to form homopolymers without any rearrangement by metal halides. Phenyl propenyl ethers were less reactive than the corresponding phenyl vinyl ethers in cationic polymerization. In order to study the electronic effect of a substituent on the reactivity, cis-p-Cl,p-CH3, and p-CH3O-phenyl propenyl ethers were copolymerized with phenyl propenyl ether in methylene chloride at ?78°C with stannic chloride–trichloroacetic acid, and their 1H- and 13C-NMR spectra were measured. The reaction constant ρ against Hammett σp was ?2.1. The cis-phenyl propenyl ethers were slightly more reactive than the corresponding trans isomers. On the other hand, an o-methyl group decreased the reactivity of phenyl propenyl ether. The low reactivity of o-methyl phenyl propenyl ether was attributed to the steric hindrance between the propagating carbocation and the monomer. 相似文献
o-Dihydroxy-4-(3,4-dimethoxyphenyl)-chromenones (coumarins; 3a,b) were synthesised from 1,2,3-trihydroxy- or 1,2,4-triacetoxybenzenes through a reaction with ethyl 3-(3,4-dimethoxyphenyl)-3-oxopropanoate in H2SO4 or CF3COOH. The chromenone-crown ethers (4a–f) were prepared from the cyclic condensation of o-dihydroxy-4-(3,4-dimethoxyphenyl)chromenones (3a,b) with poly(ethylene glycol) ditosylates, in the presence of CH3CN/alkali carbonates. The chromatographically purified original chromenone-crown ethers were identified by 1H NMR, 13C NMR, MALDI-TOF mass spectrometry and elemental analysis. The 1:1 binding constants of Li+, Na+ and K+ with the chromenone-crown ethers were estimated in acetonitrile using fluorescence emission spectroscopy. The complexing-enhanced fluorescence spectra and complexing-enhanced quenching fluorescence spectra, along with the cationic recognition rules of the crown ethers allowed the ion binding powers to be determined. 相似文献
Zusammenfassung Betain reagiert mit Phenol und seinen Alkyl- bzw. Halogenderivaten in Gegenwart von Calciumoxid in guten Ausbeuten zu Phenylmethyläthern und Phenoxyessigsäuren. Auch sterisch gehinderte Phenole lassen sich leicht in die Methyläther überführen. Verschiedene Reaktionswege werden diskutiert.
Betaine reacts with phenol and alkyl or halogen substituted phenols in the presence of CaO in good yield to phenyl methyl ethers and phenoxy acetic acids. Also phenols with steric hindrance are readily converted in methyl ethers. Various reaction pathways are discussed.
Auszugsweise vorgetragen anläßlich der Chemikertagung in Graz, September 1965.1. Mitt.:E. Ziegler, H. Wittmann undF. Orlinger, Mh. Chem.96, 208 (1965). 相似文献
ABSTRACTBenzocrown ethers incorporating phenyl and nitrophenyl urea and thiourea moieties were synthesised. Both the nitrophenyl urea and thiourea derivative gave a fluoride-specific colorimetric response but only the urea derivative bound the organophosphonate nerve agent simulants dimethyl methylphosphonate (DMMP) and diisopropyl methylphosphonate (DIMP). This suggested an application as sensors for the nerve agents sarin, soman and cyclosarin which release fluoride upon hydrolysis. Although no fluoride-induced response was observed in the UV-visible spectrum, binding to soman was determined by 1H NMR. DFT computational simulations suggested that the two crowns adopt different conformations in which both can bind fluoride but only the urea derivative can bind DMMP, DIMP and soman. The results show that, for this system, simulant- and soman-binding behaviours are in good agreement. 相似文献
Two series of aromatic enol ethers deriving from 1-methoxy-1-phenyl ethylene and from 1-methoxy-1-phenyl 2-methyl propene have been studied by 13C NMR. Comparisons between the chemical shifts of these enol ethers and those of styrene on the one hand, and aliphatic enol ethers on the other, led us to conclude that the non-coplanarity of the phenyl ring with the double bond and/or the non-coplanarity of the OCH3 group with the same double bond play a prominent role in determining the chemical shift values of the ethylenic carbons. Para-substitution on the phenyl ring induces chemical shift variation not only in the aromatic moiety itself but also in the ethylene part of the molecule. The significance of the observed Hammett correlation is discussed. 相似文献
Two novel chromogenic cone calix[4]dibenzothiacrown ethers 3 and 4 in which nitrophenylazo groups attached at the phenyl ring of dibenzothiacrown unit were described. The extraction properties
of 3 and 4 toward different transition metal ions have been studied using conductometric technique and found to exhibit Cu2+ and Hg2+ selectivity with very high stability constants range from log Kassoc = 5.19 to log Kassoc = 8.72. 相似文献
tert-Butyldimethylsilyl (TBS) phenyl / alkyl ethers were cleaved to the corresponding efficiently parent hydroxyl compounds in good yields using catalytic amounts of AlCl3 · 6H2O by conventional or microwave-assisted heating in methanol or isopropanol solution. Intramolecular and competitive experiments demonstrated the chemoselective deprotection of TBS ethers in the presence of triisopropylsilyl and tert-butyldiphenylsilyl ethers. 相似文献
Abstract Various para-substituted phenyl propargyl ethers (substitutent = H, OMe, and CN) were synthesized and polymerized by transition metal catalyst systems including MoCl5, WC16, and PdCl2. The catalytic activity of MoCl5-based catalysts was greater than that of WCl6-based catalysts for the present polymerization. The polymer yield increased in the following order: H > OMe > CN, according to substitutents. The [poly-(pheny] propargyl ether) [poly(PPE)] and poly(methoxy phenyl propargyl ether) [poly(OMe-PPE)] obtained are completely soluble in various organic solvents such as chloroform, methylene chloride, THF, and 1,4-dioxane. However, poly(cyanophenyl propargyl ether) [poly(CN-PPE)] is partially soluble in various organic solvents such as those mentioned above. The electrical conductivities of the undoped and iodine-doped polymers and found to be about 10?13 and 10?4-10?5 S/cm, respectively. The solubilities, thermal properties, and morphologies of the resulting polymers were also studied. 相似文献
The 17O chemical shifts have been measured for 51 α,β-unsaturated and aromatic ethers. A good linear relationship is found between the 17O chemical shifts in a series of dialkyl and the corresponding alkyl vinyl ethers. Hence, the extent of p,π-interaction, between the oxygen atom and the vinyl group in the latter series does not, apparently, depend upon branching at the α-carbon atom in the alkyl moiety of these ethers. The PhOBut ether, however, as compared to the other alkyl phenyl ethers, shows significantly weakened p,π-interaction, which is apparently related to the steric hindrance of this interaction. The effects of two unsaturated groups upon the 17O chemical shifts in the corresponding ethers are non-additive. This is undoubtedly a result of ‘rivalry’ between these groups for conjugation with the lone electron pairs on the ethereal oxygen. The 17O chemical shift ranges of substituted methyl and vinyl phenyl ethers are nearly equal (≈30 ppm). An analysis of the 17O shielding for cyclopropyl ethers shows no observable p,σ-conjugation in these compounds. Excellent correlation (r>0.99) between the values of 17O chemical shifts and the calculated (MO LCAO SCF, CNDO/2) π-electron charges on the corresponding oxygen atoms look promising for experimental estimations of π-electron densities on the ethereal oxygen. 相似文献
An efficient procedure for the cleavage of allyl phenyl ethers and allyl coumarinyl ethers using a catalytic amount of 10% Pd/C in combination with ammonium formate is described. Allyl ethers of phenols are deprotected in preference to those of alcohols and this method is compatible with several reducible functional groups such as CHO, COCH3, CO2Et and NHCOCH3. 相似文献
Photolysis of phenyl phenylacetate and its derivatives in homogeneous solutions results in photo-Fries rearrangement products,
phenols and diphenylethane as well as phenyl benzyl ethers. Photolysis of these esters adsorbed on silica surface leads only
to the formation of or/tho-hydroxyphenones and phenyl benzyl ethers. This observation demonstrates that silica surfaces suppress diffusion and rotation
of the photogenerated radicals. Application of a weak external magnetic field upon photolysis of these esters adsorbed on
silica surface results in no change in the product distribution, suggesting that the photochemical reaction of these esters
originates from the excited singlet state. The rate of the formation of the ortho rearrangement product from the geminate radical pairs adsorbed on silica surfaces is estimated to be 2.0 x 108 s-1. 相似文献
Phase-transfer catalysis and template assembly on sodium and cesium cations were used to prepare 2-(diphenylphosphoryl)phenyl ethers of ethylene glycols Ln with varied number of polyether units (n = 3–8). Previously unknown dinitro and disulfo derivatives of 2-(diphenylphosphoryl)phenyl ethers of di- and triethylene glycols were synthesized. Complexes [NaL4]NCS·C6H6, [NaL4]ClO4, [KL5]NCS, and [KL5]ReO4 were synthesized, and their crystal structure was studied. Structure–stability constant correlations were found for alkali metal complexes with phosphoryl podands Ln and isodentate crown ethers. 相似文献
Venlafaxine hydrochloride is a phenyl ethylamine derivative, used for the treatment of depression. During the process development of venlafaxine hydrochloride, six process-related potential impurities were detected in high-performance liquid chromatography. All these impurities were identified, synthesized, and subsequently characterized by their respective spectral data (IR, mass, 1H NMR, and 13C NMR) as described in this article. 相似文献
Abstract A series of biologically active organophosphorus compounds have been synthesized by the reactions of O,O-diethylchlorophosphate with Schiff bases derived from 5-(phenyl/substituted phenyl)-2-hydrazino-1,3,4-oxadiazole and salicylaldehyde/2-hydroxyacetophenone. The compounds have been characterized on the basis of analyses and spectral (IR, 1H, 13C NMR) data. Fungicidal activities of these derivatives against Colletotrichum falcatum, Fusarium oxysporum, and Curvularia pallescence have been evaluated. All compounds showed moderate to significant antifungal activity. 相似文献
The spin trap agent, 2,6-di-chloronitrosobenzene (DCNB), which is decomposed into a nitrogen monoxide and a chlorinated phenyl radical on slight warming, was known to act as a radical generator through hydrogen abstraction by the chlorinated phenyl radical from an adjacent molecule. An ESR spectrum was observed at room temperature from a poly(methyl methacrylate) (PMMA)-benzene solution after the addition of DCNB followed by a warming to ca 30°C. The radical concentration increased with time. The spectrum was assigned to the spin adducts of PMMA radicals generated and trapped by DCNB. Analyses of the spectra observed from normal PMMA and partially deuterated PMMA's indicated that the majority of the PMMA radicals were the chain-scission species and a minority were . It was concluded that the main-chain scissions in PMMA were caused by the radicals (D), which had been primarily produced by the chlorinated phenyl radicals. These ESR data are supported by the fact that a decrease in molecular weight of PMMA was observed after addition of DCNB, and further reinforced by the fact that a molecular weight estimated from the number of the scission radicals agreed fairly well with the measured molecular weight. Similar results were obtained when both tri-chlorinated nitrosobenzene and tetra-chlorinated nitrosobenzene were used instead of DCNB. 相似文献