RESUMEN
Tetrahydropyranones are synthesized from 3-bromobut-3-en-1-ols and aldehydes in good yields with excellent diastereoselectivity at -35 °C. The reaction involves an initial formation of a most stable six-membered chairlike tetrahydropyranyl carbocation followed by nucleophilic attack of the hydroxyl group and subsequent elimination of HBr to give tetrahydropyranone. The carbonyl moiety of the tetrahydropyranone is converted to enol ether and esters using Wittig reaction. It is also transformed into 4-hydroxy-2,6-disubstituted tetrahydropyran with 2,4- and 4,6-cis configuration by lithium aluminum hydride in up to 96% diastereoselectivity. Furthermore, the methodology is extended toward the synthesis of novel anticancer aminoguanidine compounds.
RESUMEN
The synthesis of spiro[furan-2,1'-isoindolin]-3'-ones from 2-(4-hydroxybut-1-yn-1-yl)benzonitriles and aryl aldehydes is demonstrated. It involves the initial formation of dihydrofuranylideneisoindolinone via intramolecular sequential Prins and Ritter reactions, followed by the ring opening of the furanyl moiety to generate N-acyliminium ions and alcohols for the final cyclization reaction, and the spiro-cyclic compounds are produced in moderate to good yields. It is a one-pot, three-component reaction in which one new quaternary carbon, two five-membered rings, one C-N bond, two C-O bonds, and one C-C bond are formed. The reaction is carried out with a Brønsted acid from 0 °C to room temperature within a short period of time.
RESUMEN
An efficient methodology has been developed for the synthesis of tetra- and pentasubstituted pyrroles via oxidative self-dimerization of N-propargylamines catalyzed by silver benzoate in the presence of K2S2O8 in good yields. The protocol provides a simple route for the synthesis of both tetra- and pentasubstituted pyrroles with two carbonyl groups in the side chain. The methodology can be extended toward the synthesis of pyrrolo[3,4-d]pyridazine.
RESUMEN
A simple methodology has been developed for the synthesis of substituted 9H-dibenzo[3,4:6,7]-cyclohepta[1,2-a]naphthalenes from phenylacetaldehydes and ortho-alkynyl benzyl alcohols in the presence of a Lewis acid in moderate to good yields within a short reaction time. Interestingly, the reaction proceeds through a highly regioselective electrophilic addition followed by double Friedel-Crafts reaction to form uncommon dibenzo-fused seven-membered carbocycles.
RESUMEN
A one-pot tandem reaction has been developed for the synthesis of substituted tetrahydropyrroloisoindolone via Mannich reaction of N-propargyl amido alcohols with 1,3-dicarbonyl compounds followed by Conia-ene cyclization reaction in moderate to good yields catalyzed by indium(III)triflate [In(OTf)3]. The reaction is highly regioselective with an exo-cyclic double bond in the pyrrolidine ring. The substituted tetrahydropyrroloisoindolone can be converted to 5H-pyrrolo[2,1-a]isoindol-5-one via decarboxylative aromatization reaction.
RESUMEN
The use of quantitative nuclear magnetic resonance spectrometry for the determination of non-UV active memantine hydrochloride with relative simplicity and precision has been demonstrated in this study. The method was developed on a 500 MHz NMR instrument and was applied to determination of the drug in a tablet formulation. The analysis was performed by taking caffeine as an internal standard and D2 O as the NMR solvent. The signal of methyl protons of memantine hydrochloride appeared at 0.75 ppm (singlet) relative to the signal of caffeine (internal standard) at 3.13 ppm (singlet). The method was found to be linear (r(2) = 0.9989) in the drug concentration range of 0.025 to 0.80 mg/ml. The maximum relative standard deviation for accuracy and precision was <2. The limits of detection and quantification were 0.04 and 0.11 mg/ml, respectively. The robustness of the method was revealed by changing nine different parameters. The deviation for each parameter was also within the acceptable limits. The study highlighted possibility of direct determination of memantine hydrochloride in pure form and in its marketed tablet formulation by the use of quantitative NMR, without the need of derivatization, as is the requirement in HPLC studies. Copyright © 2016 John Wiley & Sons, Ltd.
Asunto(s)
Antiparkinsonianos/análisis , Memantina/análisis , Algoritmos , Cafeína/análisis , Composición de Medicamentos , Límite de Detección , Espectroscopía de Resonancia Magnética/métodos , Estándares de Referencia , Reproducibilidad de los Resultados , ComprimidosRESUMEN
Prasugrel was subjected to forced degradation studies under conditions of hydrolysis (acid, base, and neutral), photolysis, oxidation, and thermal stress. The drug showed liability in hydrolytic as well as oxidative conditions, resulting in a total of four degradation products. In order to characterize the latter, initially mass fragmentation pathway of the drug was established with the help of mass spectrometry/time-of-flight, multiple stage mass spectrometry and hydrogen/deuterium exchange data. The degradation products were then separated on a C18 column using a stability-indicating volatile buffer method, which was later extended to liquid chromatography-mass spectrometry studies. The latter highlighted that three degradation products had the same molecular mass, while one was different. To characterize all, their mass fragmentation pathways were established in the same manner as the drug. Subsequently, liquid chromatography-nuclear magnetic resonance (NMR) spectroscopy data were collected. Proton and correlation liquid chromatography with NMR spectroscopy studies highlighted existence of diastereomeric behavior in one pair of degradation products. Lastly, toxicity prediction by computer-assisted technology (TOPKAT) and deductive estimation of risk from existing knowledge (DEREK) software were employed to assess in silico toxicity of the characterized degradation products.
Asunto(s)
Cromatografía Liquida/métodos , Espectroscopía de Resonancia Magnética/métodos , Espectrometría de Masas/métodos , Clorhidrato de Prasugrel/química , Técnicas de Química Analítica , Química Farmacéutica/métodos , Cromatografía Líquida de Alta Presión , Estabilidad de Medicamentos , Calor , Hidrólisis , Oxidación-Reducción , Oxígeno/química , Tamaño de la Partícula , Fotólisis , Clorhidrato de Prasugrel/análisis , Programas Informáticos , TemperaturaRESUMEN
The present study dealt with the forced degradation behaviour of rosuvastatin under ICH prescribed stress conditions. The drug was found to be labile under acid hydrolytic and photolytic conditions, while it was stable to base/neutral hydrolytic, oxidative and thermal stress. In total, 11 degradation products were formed, which were separated on a C-18 column using a stability-indicating method. LC-MS analyses indicated that five degradation products had the same molecular mass as that of the drug, while the remaining six had 18 Da less than the drug. Structure elucidation of all the degradation products was executed using sophisticated and modern structural characterization tools, viz. LC-MS/TOF, LC-MS(n), on-line H/D exchange and LC-NMR. The degradation pathway and mechanisms of degradation of the drug were delineated. Additionally, in silico toxicity was predicted for all the degradation products using TOPKAT and DEREK software and compared with the drug. This study demonstrates a comprehensive approach of degradation studies during the drug development phase.
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Cromatografía Liquida/métodos , Fluorobencenos/química , Espectroscopía de Resonancia Magnética/métodos , Espectrometría de Masas/métodos , Pirimidinas/química , Sulfonamidas/química , Diseño de Fármacos , Estabilidad de Medicamentos , Fluorobencenos/toxicidad , Cinética , Estructura Molecular , Pirimidinas/toxicidad , Rosuvastatina Cálcica , Sulfonamidas/toxicidadRESUMEN
A TfOH-promoted, metal-free protocol has been unveiled for the synthesis of spiro-furan quinazolinones employing alkynol urea derivatives utilizing alkynyl Prins cyclization reaction. This methodology produces highly functionalized spiro-heterocycles in excellent yields with exclusive E-selectivity under ambient conditions. Furthermore, late-stage modifications incorporate bromide and acetyl functionalities into the synthesized spiro-heterocycles.
RESUMEN
Tetrahydro-4H-pyrrolo[3,2-c]quinolin-4-ones and dihydro-1H-benzo[b]azepines are efficiently synthesized from 2-aminobenzonitriles and donor-acceptor cyclopropanes mediated by SnCl4 in moderate to good yields. The reaction involves the initial ring opening of a cyclopropane ring due to activation by SnCl4 followed by nucleophilic attack by amine to give an adduct, which after unprecedented rearrangement at two different reaction temperatures provides two nitrogen heterocyclic compounds. This methodology can be used for the synthesis of hexahydropyrrolo[3,2-c]quinolinone derivatives, the structure of which is found in biologically active molecules.
RESUMEN
Stress degradation studies were carried out on celiprolol hydrochloride under the ICH prescribed hydrolysis (acidic, basic and neutral), photolytic, oxidative and thermal conditions. Maximum degradation was observed upon hydrolysis, especially in the basic condition. In oxidative condition, the drug degraded only upon severe exposure to H2O2, but it remained stable when challenged with AIBN. It also degraded significantly under photolytic conditions. However, the drug was stable to thermal stress. A total of seven degradation products were formed, whose separation was successfully achieved on an Inertsil ODS-3V C-18 HPLC column employing a gradient mobile phase. A comprehensive mass fragmentation pattern of the drug was initially established through the support of high resolution mass spectrometry (HR-MS), multi-stage tandem mass spectrometry (MSn) and on-line H/D exchange MS data. The same approach was then extended to characterization of the degradation products. Additionally, two degradation products were isolated and subjected to 1D/2D NMR studies for their structural confirmation. One of the degradation products showed instability during isolation, therefore, it was subjected to LC-NMR studies for its structural confirmation.
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Celiprolol , Peróxido de Hidrógeno , Cromatografía Líquida de Alta Presión , Estabilidad de Medicamentos , Hidrólisis , Oxidación-Reducción , Fotólisis , Espectrometría de Masas en TándemRESUMEN
Tazarotene is a prodrug that belongs to the acetylenic class of retinoids. The drug was subjected to hydrolytic, oxidative and photolytic stress testing to establish its comprehensive degradation chemistry. The drug proved to be unstable under acidic and basic hydrolytic conditions, yielding tazarotenic acid, which is a known major degradation product (DP) and an active metabolite. Additionally, two DPs each were generated upon interaction of drug and tazarotenic acid with HCl, used as an acid stressor. These were experimentally proven as pseudo DPs, as they did not originate when H2SO4 was employed as the stressor. The drug was also unstable under oxidative and photolytic conditions, yielding six DPs. All the products were separated on reversed phase (C18) column, using mobile phase composed of 10â¯mM ammonium formate (pH 3.5) and acetonitrile, which was run in a gradient mode. The separated DPs were subjected to LC-HRMS and LC-MSn studies for their initial characterization. Seven hydrolytic and oxidative DPs that could be isolated using semi-preparative column were subjected to extensive 1D (1H, 13C and DEPT-135) and 2D (COSY, HSQC and HMBC) NMR studies to confirm their structures. In total, five novel DPs were characterized, apart from two previously reported DPs, viz., tazarotenic acid and tazarotene sulfoxide, and four additional pseudo DPs. The complete degradation pathway of the drug was established. In silico ADMET properties of the drug and its DPs were evaluated using ADMET Predictor™.
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Cromatografía Liquida/métodos , Fármacos Dermatológicos/química , Ácidos Nicotínicos/química , Simulación por Computador , Fármacos Dermatológicos/análisis , Fármacos Dermatológicos/farmacocinética , Estabilidad de Medicamentos , Hidrólisis , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Ácidos Nicotínicos/análisis , Ácidos Nicotínicos/farmacocinética , Oxidación-Reducción , FotólisisRESUMEN
Zidovudine (ZDV) and efavirenz (EFV), which belong to two separate classes of antiretroviral drugs, viz., NRTI and NNRTI, respectively, were subjected to different stability test conditions alone and in solid mixtures to evaluate possibility of interaction among them. The exposed samples were analyzed by high performance liquid chromatography (HPLC) using a C18 column and a PDA detector. Two new peaks were observed in the sample in which 50⯵l CH3CN was added to increase the contact among the drugs, and which was subjected in open beaker to accelerated stability test condition of 40⯰C/75%RH for 15 d. Subsequently, liquid chromatography-high resolution mass spectrometric (LC-HRMS) studies were carried out to obtain their accurate mass. The products were also isolated, and subjected to 1H, 13C, DEPT-135, COSY, HSQC and HMBC nuclear magnetic resonance (NMR) studies. The collective information allowed their structural characterization as isomeric cycloaddition products of the two drugs. As these were novel compounds, they were subjected to testing for cytotoxicity and in vitro anti-HIV-1 activity against primary isolates HIV-1UG070 (X4, subtype D) and HIV-1VB59 (R5, subtype C) in TZM-bl cell line. The two were found to show weak activity against the standard drugs. The reason was sought through molecular docking studies, which highlighted that it was perhaps their comparative bigger molecular size than the drugs of both classes used currently in HIV therapy. Being previously unknown molecules, their in silico physicochemical and ADMET properties were also evaluated using ADMET Predictor™ and TOPKAT software.
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Fármacos Anti-VIH/farmacología , Benzoxazinas/farmacología , Infecciones por VIH/tratamiento farmacológico , VIH-1/efectos de los fármacos , Zidovudina/farmacología , Alquinos , Línea Celular Tumoral , Cromatografía Líquida de Alta Presión/métodos , Ciclopropanos , Combinación de Medicamentos , Estabilidad de Medicamentos , Humanos , Espectroscopía de Resonancia Magnética/métodos , Simulación del Acoplamiento MolecularRESUMEN
Bepotastine (BPT) is a H1-receptor antagonist. It is used as a besilate salt in ophthalmic solution for allergic conjunctivitis and orally for the treatment of allergic rhinitis and urticaria/pruritus. Its systematic forced degradation study is unreported. The same was carried out in different conditions prescribed by International Conference on Harmonisation. The stressed solutions were subjected to reversed phase liquid chromatographic analysis, and BPT was observed to be labile under photobasic condition only, yielding 5 photodegradation products. The structures of the latter were elucidated from data generated by liquid chromatography-high-resolution mass spectrometry and multistage mass spectrometry. Of the 5, 4 products were further isolated and subjected to nuclear magnetic resonance spectroscopy to justify the proposed structures. Two of them, with similar accurate mass, were additionally and unambiguously characterized from their heteronuclear multiple bond correlation data, hydrogen deuterium exchange mass data, and quantum chemical analysis using density functional theory calculations. One degradation product had a structure that could only be explained by unusual rearrangement involving conversions of N-oxide into hydroxylamine, similar to Meisenheimer rearrangement. The physicochemical, as well as absorption, distribution, metabolism, excretion, and toxicity properties of BPT and its characterized photodegradation products were evaluated in silico by ADMET Predictor™ software.
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Conjuntivitis Alérgica , Simulación por Computador , Cromatografía de Gases y Espectrometría de Masas , Humanos , Fotólisis , Piperidinas , PiridinasRESUMEN
Incompatibility studies of antiretroviral drugs, viz., lamivudine (3TC), emtricitabine (FTC), abacavir sulfate (ABC), tenofovir disoproxil fumarate (TDF), zidovudine (ZDV), efavirenz (EFV) and nevirapine (NVP) were carried out in the presence of ten selected excipients, i.e., microcrystalline cellulose, lactose monohydrate, starch, magnesium stearate, sodium lauryl sulfate, sodium starch glycolate, croscarmellose sodium, colloidal silica, povidone K-30 and hydroxypropyl cellulose. Among all, ABC showed reaction with lactose monohydrate, resulting in the formation of two interaction products, while sodium lauryl sulphate enhanced the degradation of TDF. The interaction products of ABC-Lactose were separated by high performance liquid chromatography (HPLC) and subjected to liquid chromatography-high resolution mass spectrometry (LC-HRMS) studies for their characterization. One of the products was also isolated and subjected to 1D and 2D nuclear magnetic resonance (NMR) studies for structural confirmation. The toxicity of both was predicted using TOPKAT and ADMET™ software and compared to the drug.
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Antirretrovirales , Excipientes , Modelos Biológicos , Animales , Antirretrovirales/química , Antirretrovirales/metabolismo , Antirretrovirales/toxicidad , Cromatografía Líquida de Alta Presión , Simulación por Computador , Interacciones Farmacológicas , Estabilidad de Medicamentos , Excipientes/química , Excipientes/metabolismo , Excipientes/toxicidad , Humanos , Espectroscopía de Resonancia Magnética , Estructura Molecular , Valor Predictivo de las Pruebas , Espectrometría de Masas en TándemRESUMEN
The present study focused upon the forced degradation behaviour of fosamprenavir (FPV), an antiretroviral drug. A total of six degradation products (DPs) were separated on a non-polar stationary phase by high performance liquid chromatography (HPLC). For the characterization, comprehensive mass fragmentation pathway of the drug was initially established using high resolution mass spectrometry (HRMS) and multi-stage tandem mass spectrometry (MSn) data. Subsequently, LC-HRMS and LC-MSn studies were carried out on the forced degraded samples containing the DPs. Five DPs were isolated and subjected to extensive 1D (1H, 13C, and DEPT-135 (distortionless enhancement by polarization)) and 2D (COSY (correlation spectroscopy), TOCSY (total correlation spectroscopy), HSQC (heteronuclear single quantum coherence) and HMBC (heteronuclear multiple bond correlation)) nuclear magnetic resonance (NMR) studies to ascertain their structures, while one degradation product was subjected to LC-NMR studies, as it could not be isolated. The collated information was helpful in characterization of all the DPs, and to delineate the degradation pathway of the drug. Additionally, physicochemical, as well as absorption, distribution, metabolism, excretion and toxicity (ADMET) properties of the drug and its DPs were evaluated in silico by ADMET Predictor™ software.
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Antirretrovirales/química , Carbamatos/química , Organofosfatos/química , Sulfonamidas/química , Cromatografía Líquida de Alta Presión/métodos , Simulación por Computador , Estabilidad de Medicamentos , Furanos , Espectroscopía de Resonancia Magnética/métodos , Programas Informáticos , Espectrometría de Masas en Tándem/métodos , Distribución Tisular/efectos de los fármacosRESUMEN
Efavirenz (EFV), an antiretroviral drug, was evaluated for its degradation behaviour in solution state. A total of twelve degradation products were detected on high performance liquid chromatography (HPLC) analyses. Initially, comprehensive mass fragmentation pattern of the drug was established by direct injection and collection of high resolution mass spectrometry (HRMS) and multi-stage tandem mass spectrometry (MSn) data. Subsequently, LC-HRMS studies were carried on the stability samples containing the degradation products. Eleven degradation products were isolated and subjected to 1D and 2D nuclear magnetic resonance (NMR) studies for their structural confirmation. The collated information was utilized for the characterization of all the degradation products and hence in outlining the comprehensive degradation pathway of the drug. In-silico toxicity of the degradation products was evaluated by TOPKAT analyses.
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Antirretrovirales/química , Benzoxazinas/química , Alquinos , Cromatografía Líquida de Alta Presión/métodos , Simulación por Computador , Ciclopropanos , Estabilidad de Medicamentos , Espectroscopía de Resonancia Magnética/métodos , Espectrometría de Masas en Tándem/métodosRESUMEN
Forced degradation studies on aliskiren were carried out according to ICH and WHO guidelines. Six degradation products were formed in total in the solution state. Their separation among themselves and from the drug was successfully achieved on a C-18 column utilizing acetonitrile and phosphate buffer (pHâ¯3.0) in the mobile phase, which was run in a gradient mode. To characterize them, a complete mass fragmentation pathway of the drug was first established with the help of MS/TOF and MSn data. This was followed by LC-MS/TOF studies on the degradation products. Some of the degradation products were also isolated and subjected to 1D (1H, 13C and DEPT-135) and 2D (COSY, HSQC and HMBC) NMR studies for confirmation of their structures. An interesting observation was hydrolysis followed by cyclization in case of three degradation products. Also, acetonitrile was found to react with aliskiren, leading to formation of a pseudo degradation product. Additionally, comparative ADMET properties of the drug and degradation products were established using ADMET Predictor™.
Asunto(s)
Amidas , Antihipertensivos , Fumaratos , Amidas/química , Amidas/farmacocinética , Amidas/toxicidad , Animales , Antihipertensivos/química , Antihipertensivos/farmacocinética , Antihipertensivos/toxicidad , Ciclización , Sistema Enzimático del Citocromo P-450/metabolismo , Estabilidad de Medicamentos , Fumaratos/química , Fumaratos/farmacocinética , Fumaratos/toxicidad , Corazón/efectos de los fármacos , Humanos , Concentración de Iones de Hidrógeno , Hidrólisis , Ratas , Soluciones , Rayos UltravioletaRESUMEN
In the present study, degradation behaviour of abacavir sulfate was evaluated in solution and solid stress conditions. Solution state studies resulted in formation of eleven degradation products; of which two were also formed on solid stress. The same were separated by high performance liquid chromatography. They were characterized using liquid chromatography-high resolution mass spectrometry, liquid chromatography-multistage mass spectrometry and hydrogen/deuterium exchange mass spectrometry data. Additionally, seven degradation products were isolated and subjected to 1D and 2D nuclear magnetic resonance studies for their structural confirmation.
Asunto(s)
Antirretrovirales/análisis , Didesoxinucleósidos/análisis , Espectroscopía de Resonancia Magnética/métodos , Antirretrovirales/química , Cromatografía Líquida de Alta Presión/métodos , Didesoxinucleósidos/química , Combinación de Medicamentos , Estabilidad de Medicamentos , Espectrometría de Masas/métodosRESUMEN
This study focused on drug-drug interaction behaviour among lamivudine (3TC) and tenofovir disoproxil fumarate (TDF), the two anti-retroviral drugs. Apart from pre-known degradation products of individual drugs, a total of twelve interaction products were detected by high performance liquid chromatography (HPLC) using a C18 column as the stationary phase, and methanol and ammonium formate in gradient mode as the mobile phase. The same HPLC method was employed for liquid chromatography-high resolution mass spectrometry (LC-HRMS) and liquid chromatography-multi stage mass spectrometry (LC-MS(n)). For the characterization of interaction products, stability samples were subjected to LC-HRMS, LC-MS(n) and online hydrogen/deuterium exchange studies. Two isomeric interaction products were isolated and subjected to 1D and 2D nuclear magnetic resonance (NMR) studies. The collated information was utilized for the characterization of all twelve interaction products of the two drugs. Pathway of their formation was also outlined.