Home About us Contact
|
Home About us Contact | ||
|
|
||
Compound III (compound + iii)
Selected AbstractsThe Reaction of o -Alkynylarene and Heteroarene Carboxaldehyde Derivatives with Iodonium Ions and Nucleophiles: A Versatile and Regioselective Synthesis of 1H -Isochromene, Naphthalene, Indole, Benzofuran, and Benzothiophene CompoundsCHEMISTRY - A EUROPEAN JOURNAL, Issue 22 2006José Barluenga Prof. Dr. Abstract The reaction of o -alkynylbenzaldehydes 1 with different alcohols, silylated nucleophiles 5, electron-rich arenes 10, and heteroarenes 12 in the presence of the reagent IPy2BF4, at room temperature, gave functionalized 4-iodo-1H -isochromenes 2, 6, 11, and 13 in a regioselective manner. When alkynes 16 and alkenes 19 and 20 were used as nucleophiles, a regioselective benzannulation reaction took place to form 1-iodonaphthalenes 17 and 1-naphthyl ketones 18, respectively. Moreover, the latter process has been adapted to accomplish the synthesis of indole, benzofuran, and benzothiophene derivatives (23, 27, and 28, respectively). The three patterns of reactivity observed for the o -alkynylbenzaldehyde derivatives with IPy2BF4 stem from a common iodinated isobenzopyrylium ion intermediate, A, that evolves in a different way depending on the nucleophile present in the reaction medium. A mechanism is proposed and the different reaction pathways observed as a function of the type of nucleophile are discussed. Furthermore, the reaction of the o -hexynylbenzaldehyde 1,b with styrene was monitored by NMR spectroscopy. Compound III, a resting state for the common intermediate in the absence of acid, has been isolated. Its evolution in acid media has been also tested, thereby providing support to the proposed mechanism. [source] The effect of pH on horseradish peroxidase-catalyzed oxidation of melatonin: production of N1 -acetyl- N2 -formyl-5-methoxykynuramine versus radical-mediated degradationJOURNAL OF PINEAL RESEARCH, Issue 3 2007Valdecir F. Ximenes Abstract:, There is a growing body of evidence that melatonin and its oxidation product, N1 -acetyl- N2 -formyl-5-methoxykynuramine (AFMK), have anti-inflammatory properties. From a nutritional point of view, the discovery of melatonin in plant tissues emphasizes the importance of its relationship with plant peroxidases. Here we found that the pH of the reaction mixture has a profound influence in the reaction rate and products distribution when melatonin is oxidized by the plant enzyme horseradish peroxidase. At pH 5.5, 1 mm of melatonin was almost completely oxidized within 2 min, whereas only about 3% was consumed at pH 7.4. However, the relative yield of AFMK was higher in physiological pH. Radical-mediated oxidation products, including 2-hydroxymelatonin, a dimer of 2-hydroxymelatonin and O -demethylated dimer of melatonin account for the fast consumption of melatonin at pH 5.5. The higher production of AFMK at pH 7.4 was explained by the involvement of compound III of peroxidases as evidenced by spectral studies. On the other hand, the fast oxidative degradation at pH 5.5 was explained by the classic peroxidase cycle. [source] A direct injection high-throughput liquid chromatography tandem mass spectrometry method for the determination of a new orally active ,v,3 antagonist in human urine and dialysateRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 22 2003Wei Zeng A generic high-throughput liquid chromatography (HTLC) tandem mass spectrometry (MS/MS) assay for the determination of compound I in human urine and dialysate (hemodialysis) was developed and validated. By using the HTLC on-line extraction technique, sample pretreatment was not necessary. The sample was directly injected onto a narrow bore large particle size extraction column (50,×,1.0,mm, 60,,m) where the sample matrix was rapidly washed away using a high flow rate (5,mL/min) aqueous mobile phase while analytes were retained. The analytes were subsequently eluted from the extraction column onto an analytical column using an organic-enriched mobile phase prior to mass spectrometric detection. The analytes were then eluted from the analytical column to the mass spectrometer for the determination. The linear dynamic range was 2.0,6000,ng/mL for the urine assay and 0.1,300,ng/mL for the dialysate assay. Intraday accuracy and precision were evaluated by analyzing five replicates of calibration standards at all concentrations used to construct the standard curve. For the urine assay, the precision (RSD%, n,=,5) ranged from 1.9 to 8.0% and the accuracy ranged from 87.8 to 105.2% of nominal value. For the dialysate assay, the precision (RSD%, n,=,5) ranged from 1.1 to 10.0% and the accuracy from 94.5 to 105.2% of nominal value. In-source fragmentation of the acyl glucuronide metabolite (compound III) did not interfere with the determination of parent compound I. The developed HTLC/MS/MS methodology was specific for compound I in the presence of compound III. Column life-time is increased and sample analysis time is decreased over traditional reversed-phase methods when direct injection assays for urine and dialysate are coupled with the technology of HTLC. Copyright © 2003 John Wiley & Sons, Ltd. [source] 6-Substituted Indolo[1,2- c]quinazolines as New Antimicrobial AgentsARCHIV DER PHARMAZIE, Issue 9 2009Rondla Rohini Abstract A series of 2- o -arylidineaminophenylindoles and their cyclic derivatives (indolo[1,2- c]quinazolines) were synthesized. The reactions occurred under relatively mild conditions and afforded the desired product in good yields. Molecular structures of the synthesized compounds were confirmed by IR, 1H-NMR, 13C-NMR, MS spectra, and elemental analyses. Furthermore, all the final products were screened for in-vitro antibacterial activity against three Gram-positive and three Gram-negative bacteria and also tested for their inhibitory action against three strains of fungi. Compound IIc showed potent activity against all the bacterial (except S. typhimurium) and fungal strains. Especially, compounds IIi and IIj which have isoquinolyl and pyridyl substituents displayed potent antibacterial as well as antifungal activities compared to those of the respective standard drugs Ampicillin and Ketoconazole. [source] | ||||||||||