Objective: Using cyclic (CV) and differential pulse (DPV) voltammetric techniques, the electroche... more Objective: Using cyclic (CV) and differential pulse (DPV) voltammetric techniques, the electrochemical research of otilonium bromide (OTB) was carried out over a wide pH range (0.3–12) at glassy carbon electrodes (GCE) and boron-doped diamond electrodes (BDDE). The typical electrochemical behavior of OTB was identified as being dependent on the type of working electrode and pH. This research aims to provide a brand-new electroanalytical technique for measuring OTB in buffer solutions. Material and Method: All experiments employed the typical three-electrode cell of 10 ml capacity in conjunction with a platinum wire counter electrode, a BDDE and GCE working electrode, and an Ag/AgCl reference electrode. NOVA 1.8 software and an AUTOLAB 204 potentiostat/galvanostat were used for electrochemical measurements. Result and Discussion: The electrochemical behavior of OTB, which belongs to a class of drugs called 'antispasmodics' (spasm and cramps reliever), primarily used to treat ...
Ring opening reactions O 0132 Reaction of 2-Alkylidenetetrahydrofurans with Boron Tribromide: Che... more Ring opening reactions O 0132 Reaction of 2-Alkylidenetetrahydrofurans with Boron Tribromide: Chemo-and Regioselective Synthesis of 6-Bromo-3-oxoalkanoates by Application of a "Cyclization-Ring-Opening" Strategy.-A chemo-and regioselective approach to 6-bromo-3-oxoalkanoates (II) (17 examples), benzofuran (IV) and dibromoheptanones (VI) via reaction of appropriate ylidenetetrahydrofurans with boron tribromide is described.
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Furan derivatives R 0060 Convenient Synthesis of ε-Halo-β-ketoesters and γ,γ'-Dibromoalkanones by... more Furan derivatives R 0060 Convenient Synthesis of ε-Halo-β-ketoesters and γ,γ'-Dibromoalkanones by Regio-and Chemoselective Reaction of 2-Alkylidenetetrahydrofurans with Boron Trihalides: A "Ring-Closure/Ring-Cleavage" Strategy.-The products are versatile building blocks.-(
The Lewis acid mediated cyclization of epoxides with 1,3-bis(trimethylsilyloxy)-1,3-butadienes, e... more The Lewis acid mediated cyclization of epoxides with 1,3-bis(trimethylsilyloxy)-1,3-butadienes, electroneutral equivalents of 1,3-dicarbonyl dianions, results in the formation of 2-alkylidenetetrahydrofurans with a great variety of substitution patterns and functional groups. This includes the synthesis of 2,3'-bifuranylidenes and 7-oxabicyclo[4.3.0]nonanes. The cyclization of dienes with functionalized epoxides containing base-labile groups proceeds with good chemoselectivity. In all reactions, good regio-and E diastereoselectivities are observed. Based on the stereoselectivities observed for reactions of 1,2-disubstituted epoxides, a working hypothesis for the mechanism of the reaction is suggested.
S2 General Comments S2 Experimental Section S20 Copies of NMR spectra S2 General Comments. All so... more S2 General Comments S2 Experimental Section S20 Copies of NMR spectra S2 General Comments. All solvents were dried by standard methods and all reactions were carried out under an inert atmosphere. For the 1 H and 13 C NMR spectra the deuterated solvents indicated were used. Mass spectral data (MS) were obtained by electron ionization (70 eV), chemical ionization (CI, H 2 O) or the electrospray ionization (ESI). For preparative scale chromatography silica gel (60-200 mesh) was used. Melting points are uncorrected. Experimental Section General procedure for the reaction of 2-alkylidenetetrahydrofurans with Nbromosuccinimide (NBS): To a CCl 4-solution (5 mL/mmol) of the 2alkylidenetetrahydrofuran 2 (1 equiv.) was added N-bromosuccinimide (1.1 equiv.) at 20 °C. The reaction mixture was heated and stirred at reflux for 3 h. Then, the reaction mixture was allowed to cool down to ambient temperature and the solvent was removed in vacuo. The residue was purified by chromatography (silica gel, n-hexane/EtOAc) to give the bromo-2alkylidenetetrahydrofurans 3,4,6. Synthesis of 3, 4a: Starting with 2a (4.000 g, 28.0 mmol) and NBS (6.511 g, 36.6 mmol) in CCl 4 (40 mL), Z-3a (5.212 g, 84%) and E-4a (0.937 g, 11%) were isolated after chromatography (silica gel, n-hexane/EtOAc = 100:1 → 1:1) as yellowish and colorless solids, respectively. Methyl Bromo(dihydrofuran-2(3H)-ylidene)acetate (Z-3a):
ABSTRACT A review dealing with the synthesis of 2-alkylidenetetrahydrofurans and the reactions of... more ABSTRACT A review dealing with the synthesis of 2-alkylidenetetrahydrofurans and the reactions of 2-alkylidenetetrahydrofurans such as alkylations, brominations, Suzuki coupling reactions, hydrogenation, etc. [on SciFinder(R)]
General. All solvents were dried by standard methods and all reactions were carried out under an ... more General. All solvents were dried by standard methods and all reactions were carried out under an inert atmosphere. For the 1 H and 13 C NMR spectra (1 H NMR: 200, 300 MHz, 13 C NMR: 50, 75 MHz) the deuterated solvents indicated were used. Mass spectrometric data (MS) were obtained using the electron ionization (70 eV), the chemical ionization (CI, H 2 O) or the electrospray ionization technique (ESI). For preparative scale chromatography silica gel (60-200 mesh) was used. Melting points are uncorrected Representative Experimental Procedure for the Alkylation of 1,3-Dicarbonyl Dianions: LDA was prepared by addition of nBuLi (25.10 mL, 40.00 mmol, 15% in nhexane) to a solution of diisopropylamine (5.60 mL, 40.00 mmol) in THF (100 mL). To this solution was added tert-butylacetoacetate (3.30 mL, 20.00 mmol) at 0 °C. The deep yellow clear solution was stirred at 0 °C for 1 h. To this solution was added 1-iodo-3-methylbutane (4.492 g, 22.00 mmol) at-78 °C. The temperature was allowed to rise to ambient during 14 h and the solution was stirred at room temperature for 2 h. To the solution was added hydrochloric acid (200 mL, 10%) and the mixture was extracted with diethylether (4 x 250 mL). The organic layers were dried over Na 2 SO 4 , filtered and the solvent of the filtrate was removed in vacuo. The residue was purified by chromatography (silica gel, n-hexane → nhexane/EtOAc = 50:1) to give 2g (4.495 g, 98%) as a yellow oil.
In this study, a novel, fast, selective, and sensitive molecularly imprinted polymer (MIP)-based ... more In this study, a novel, fast, selective, and sensitive molecularly imprinted polymer (MIP)-based electrochemical sensor was developed to determine axitinib (AXI) at low concentrations in pharmaceutical dosage forms and human serum. The newly developed MIP-based sensor (MIP@o-PD/GCE) was designed through electropolymerization of functional monomer o-phenylenediamine (o-PD) in the presence of a template molecule AXI, on a glassy carbon electrode (GCE) using cyclic voltammetry. Differential pulse voltammetry and electrochemical impedance spectroscopy (EIS) techniques were employed for removal and rebinding processes, optimization of conditions, as well as for performance evaluation of MIP@o-PD/GCE using [Fe(CN)6]3-/4- as the redox probe. Under the optimum experimental conditions, MIP@o-PD/GCE shows a linear response toward AXI in a range of 1 × 10-13 M - 1 × 10-12 M. The limit of the detection value of MIP@o-PD/GCE was found as 0.027 pM while the limit of the quantification was obtained as 0.089 pM, respectively. To demonstrate the applicability and validity of the developed sensor, it was successfully applied to tablet dosage form and human serum sample. The selectivity of the sensor was qualified by comparing the binding of AXI, erlotinib, dasatinib, nilotinib, and imatinib, which are similarly structured and in the same group of anticancer drugs. MIP@o-PD/GCE sensor showed a significant selectivity toward AXI. The non-imprinted polymer (NIP) based GCE was prepared and used to control the analytical performance of the MIP-based electrochemical sensor.
Objective: Using cyclic (CV) and differential pulse (DPV) voltammetric techniques, the electroche... more Objective: Using cyclic (CV) and differential pulse (DPV) voltammetric techniques, the electrochemical research of otilonium bromide (OTB) was carried out over a wide pH range (0.3–12) at glassy carbon electrodes (GCE) and boron-doped diamond electrodes (BDDE). The typical electrochemical behavior of OTB was identified as being dependent on the type of working electrode and pH. This research aims to provide a brand-new electroanalytical technique for measuring OTB in buffer solutions. Material and Method: All experiments employed the typical three-electrode cell of 10 ml capacity in conjunction with a platinum wire counter electrode, a BDDE and GCE working electrode, and an Ag/AgCl reference electrode. NOVA 1.8 software and an AUTOLAB 204 potentiostat/galvanostat were used for electrochemical measurements. Result and Discussion: The electrochemical behavior of OTB, which belongs to a class of drugs called 'antispasmodics' (spasm and cramps reliever), primarily used to treat ...
Ring opening reactions O 0132 Reaction of 2-Alkylidenetetrahydrofurans with Boron Tribromide: Che... more Ring opening reactions O 0132 Reaction of 2-Alkylidenetetrahydrofurans with Boron Tribromide: Chemo-and Regioselective Synthesis of 6-Bromo-3-oxoalkanoates by Application of a "Cyclization-Ring-Opening" Strategy.-A chemo-and regioselective approach to 6-bromo-3-oxoalkanoates (II) (17 examples), benzofuran (IV) and dibromoheptanones (VI) via reaction of appropriate ylidenetetrahydrofurans with boron tribromide is described.
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Furan derivatives R 0060 Convenient Synthesis of ε-Halo-β-ketoesters and γ,γ'-Dibromoalkanones by... more Furan derivatives R 0060 Convenient Synthesis of ε-Halo-β-ketoesters and γ,γ'-Dibromoalkanones by Regio-and Chemoselective Reaction of 2-Alkylidenetetrahydrofurans with Boron Trihalides: A "Ring-Closure/Ring-Cleavage" Strategy.-The products are versatile building blocks.-(
The Lewis acid mediated cyclization of epoxides with 1,3-bis(trimethylsilyloxy)-1,3-butadienes, e... more The Lewis acid mediated cyclization of epoxides with 1,3-bis(trimethylsilyloxy)-1,3-butadienes, electroneutral equivalents of 1,3-dicarbonyl dianions, results in the formation of 2-alkylidenetetrahydrofurans with a great variety of substitution patterns and functional groups. This includes the synthesis of 2,3'-bifuranylidenes and 7-oxabicyclo[4.3.0]nonanes. The cyclization of dienes with functionalized epoxides containing base-labile groups proceeds with good chemoselectivity. In all reactions, good regio-and E diastereoselectivities are observed. Based on the stereoselectivities observed for reactions of 1,2-disubstituted epoxides, a working hypothesis for the mechanism of the reaction is suggested.
S2 General Comments S2 Experimental Section S20 Copies of NMR spectra S2 General Comments. All so... more S2 General Comments S2 Experimental Section S20 Copies of NMR spectra S2 General Comments. All solvents were dried by standard methods and all reactions were carried out under an inert atmosphere. For the 1 H and 13 C NMR spectra the deuterated solvents indicated were used. Mass spectral data (MS) were obtained by electron ionization (70 eV), chemical ionization (CI, H 2 O) or the electrospray ionization (ESI). For preparative scale chromatography silica gel (60-200 mesh) was used. Melting points are uncorrected. Experimental Section General procedure for the reaction of 2-alkylidenetetrahydrofurans with Nbromosuccinimide (NBS): To a CCl 4-solution (5 mL/mmol) of the 2alkylidenetetrahydrofuran 2 (1 equiv.) was added N-bromosuccinimide (1.1 equiv.) at 20 °C. The reaction mixture was heated and stirred at reflux for 3 h. Then, the reaction mixture was allowed to cool down to ambient temperature and the solvent was removed in vacuo. The residue was purified by chromatography (silica gel, n-hexane/EtOAc) to give the bromo-2alkylidenetetrahydrofurans 3,4,6. Synthesis of 3, 4a: Starting with 2a (4.000 g, 28.0 mmol) and NBS (6.511 g, 36.6 mmol) in CCl 4 (40 mL), Z-3a (5.212 g, 84%) and E-4a (0.937 g, 11%) were isolated after chromatography (silica gel, n-hexane/EtOAc = 100:1 → 1:1) as yellowish and colorless solids, respectively. Methyl Bromo(dihydrofuran-2(3H)-ylidene)acetate (Z-3a):
ABSTRACT A review dealing with the synthesis of 2-alkylidenetetrahydrofurans and the reactions of... more ABSTRACT A review dealing with the synthesis of 2-alkylidenetetrahydrofurans and the reactions of 2-alkylidenetetrahydrofurans such as alkylations, brominations, Suzuki coupling reactions, hydrogenation, etc. [on SciFinder(R)]
General. All solvents were dried by standard methods and all reactions were carried out under an ... more General. All solvents were dried by standard methods and all reactions were carried out under an inert atmosphere. For the 1 H and 13 C NMR spectra (1 H NMR: 200, 300 MHz, 13 C NMR: 50, 75 MHz) the deuterated solvents indicated were used. Mass spectrometric data (MS) were obtained using the electron ionization (70 eV), the chemical ionization (CI, H 2 O) or the electrospray ionization technique (ESI). For preparative scale chromatography silica gel (60-200 mesh) was used. Melting points are uncorrected Representative Experimental Procedure for the Alkylation of 1,3-Dicarbonyl Dianions: LDA was prepared by addition of nBuLi (25.10 mL, 40.00 mmol, 15% in nhexane) to a solution of diisopropylamine (5.60 mL, 40.00 mmol) in THF (100 mL). To this solution was added tert-butylacetoacetate (3.30 mL, 20.00 mmol) at 0 °C. The deep yellow clear solution was stirred at 0 °C for 1 h. To this solution was added 1-iodo-3-methylbutane (4.492 g, 22.00 mmol) at-78 °C. The temperature was allowed to rise to ambient during 14 h and the solution was stirred at room temperature for 2 h. To the solution was added hydrochloric acid (200 mL, 10%) and the mixture was extracted with diethylether (4 x 250 mL). The organic layers were dried over Na 2 SO 4 , filtered and the solvent of the filtrate was removed in vacuo. The residue was purified by chromatography (silica gel, n-hexane → nhexane/EtOAc = 50:1) to give 2g (4.495 g, 98%) as a yellow oil.
In this study, a novel, fast, selective, and sensitive molecularly imprinted polymer (MIP)-based ... more In this study, a novel, fast, selective, and sensitive molecularly imprinted polymer (MIP)-based electrochemical sensor was developed to determine axitinib (AXI) at low concentrations in pharmaceutical dosage forms and human serum. The newly developed MIP-based sensor (MIP@o-PD/GCE) was designed through electropolymerization of functional monomer o-phenylenediamine (o-PD) in the presence of a template molecule AXI, on a glassy carbon electrode (GCE) using cyclic voltammetry. Differential pulse voltammetry and electrochemical impedance spectroscopy (EIS) techniques were employed for removal and rebinding processes, optimization of conditions, as well as for performance evaluation of MIP@o-PD/GCE using [Fe(CN)6]3-/4- as the redox probe. Under the optimum experimental conditions, MIP@o-PD/GCE shows a linear response toward AXI in a range of 1 × 10-13 M - 1 × 10-12 M. The limit of the detection value of MIP@o-PD/GCE was found as 0.027 pM while the limit of the quantification was obtained as 0.089 pM, respectively. To demonstrate the applicability and validity of the developed sensor, it was successfully applied to tablet dosage form and human serum sample. The selectivity of the sensor was qualified by comparing the binding of AXI, erlotinib, dasatinib, nilotinib, and imatinib, which are similarly structured and in the same group of anticancer drugs. MIP@o-PD/GCE sensor showed a significant selectivity toward AXI. The non-imprinted polymer (NIP) based GCE was prepared and used to control the analytical performance of the MIP-based electrochemical sensor.
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