Pteridines, IXC. Synthesis, Oxidations and Reactions of 6- and 7-Hydroxy-2-thiolumazines Selective Cytotoxicity of Carboxypeptidase-activated Methotrexate ex-Peptides

Pteridines ◽  
1989 ◽  
Vol 1 (1) ◽  
pp. 57-63 ◽  
Author(s):  
Michael Bartke ◽  
Wolfgang Pfleiderer
Keyword(s):  
Elevated Temperature ◽  
Formic Acid ◽  
Nmr Spectra ◽  
Ammonium Acetate ◽  
Oxidative Desulfurization ◽  
Basic Medium ◽  
Methyl Derivative ◽  
Selective Cytotoxicity ◽  
Temperature Form ◽  
Elemental Analyses

Summary Various 6-(10, 11) and 7-hydroxy-2-thiolumazines (8,9) have been synthesized and oxidations of the thioamide function studied . H20 2 Oxidation of 7-hydroxy-2-thiolumazine (8) in basic medium leads to pteridine-4,7- dione-2-sulfinate (12), which eliminates S02 in anhydrous acids. Oxidative desulfurization of 8 and its 8- methyl derivative 9 proceeds directly in formic acid with H20 2 and m-chloroperbenzoic acid to give 16 and 17 respectively. KMn04 oxidation forms the pteridine-4,7,dione-2-sulfonates (14, 15), which react under hydrolytic conditions to give the corresponding 2-hydroxy derivtives (18, 19) and on displacement with ammonium acetate/ammonia at elevated temperature form the pterin derivatives 20 and 21.2-Thio-pteridine-4,6-dione (10) oxidizes also to the corresponding 2-sulfonate (22), which could only be isolated after addition of potassium bisulfite in the form of the dipotassium 7,8-dihydropteridine-4,6-dione- 2,7-disulfonate (23) adduct.The newly synthesized compounds have been characterized by elemental analyses, pKa determinations, UVand IH-NMR-spectra.

Pteridines, LXXXVIII. Oxidations and Reactions of 2- and 4-Thiolumazine Derivatives. Synthesis and Properties of Pteridine-Sulfinates and -sulfonates

Pteridines ◽  
1989 ◽  
Vol 1 (1) ◽  
pp. 45-56 ◽  
Author(s):  
Michael Bartke ◽  
Wolfgang Pfleiderer
Keyword(s):  
Formic Acid ◽  
Oxidative Desulfurization ◽  
Basic Medium ◽  
Hydroxy Derivative ◽  
Potassium Salts ◽  
Mild Conditions ◽  
Nucleophilic Displacement ◽  
Acid And Base ◽  
Displacement Reactions ◽  
Pka Determination

Summary Selective oxidations of 2-thiolumazines (10-12) by H20 2 and KMn04 respectively in basic medium led to the corresponding stable pteridin-4-one-2-sulfinates (13-15) and -sulfonates (16-18), which can be isolated in the form of their potassium salts. On oxidation of 6,7-diphenyl-2-thiolumazine (12) with 1 equivalent of H20 2 resulted the 6,7-diphenyl-pteridin-4-one-2-sulfenate (22), which is regarded as an intermediate in the formation of the sulfinates. Characterization was done by elemental analysis, pKa determination, and UV-, IR- and IH-NMR-spectra.Acid and base hydrolyse the sulfinate and sulfonate groups to the 2-hydroxy derivative. Treatment of the pteridin-4-one-2-sulfinate with strong anhydrous acids such as formic acid or sulfuric acid affects S02 elimination to the corresponding 2-H-pteridin-4-one (19-21).The oxidative desulfurization of 2-thiolumazines can be achieved directly with H20 2 and m-chloroperbenzoic acid in formic acid. Analogously nucleophilic displacement reactions of the 2-thione group proceeded under mild conditions by H20 2 oxidation in the presence of various amines to give the corresponding pterin derivatives (25.-;-32, 36-39). 6,7-Diphenyl-4-thiolumazine (44) shows similar reactions on oxidation in the presence of amines (43, 54), but the corresponding 4-sulfinate and sulfonate are too unstable in this series to be isolated. S02 elimination does not take place since hydrolysis is the preferred reaction mode.

Pteridines, XC Syntheses, Oxidations, Properties, and Reactions of 2-Thiopteridine-4,6, 7- trione Derivatives

Pteridines ◽  
1989 ◽  
Vol 1 (2) ◽  
pp. 83-90 ◽  
Author(s):  
Michael Bartke ◽  
Wolfgang Pfleiderer
Keyword(s):  
Oxalic Acid ◽  
Formic Acid ◽  
Oxidative Desulfurization ◽  
Uv Spectra ◽  
Sulfonate Group ◽  
Efficient Synthesis ◽  
Ring Contraction ◽  
Dimethyl Oxalate ◽  
Elemental Analyses ◽  
H 20

Summary A new efficient synthesis for 2-thiopteridine-4,6,7-triones (6-10, 15) has been found in the condendation of the appropriate 5,6-diaminopyrimidine (1-5, 14) with oxalic acid in DMF. Analogous condensations with dimethyl oxalate led to S-alkylation probably via an intermediate O-methylation of the DMF. 8-Methyl-2- thiopteridine-4,6,7-trione (10) shows a ring contraction to 9-methyl-2-thioxanthine (13) on base treatment. Oxidations by H20 2 and KMn04 respectively lead to the corresponding 2-sulfinate 22 and the 2-sulfonates 17 -19. Oxidative desulfurization takes place in formic acid with H 20 2 forming first the sulfinate 22, which then eliminates S02 to give pteridine-4,6,7-trione (23). Nucleophilic displacements of the 2-sulfonate group by ammonia and amines form the corresponding leucopterin derivatives 20, 21 and 24. The newly synthesized compounds have been characterized by elemental analyses, UV-spectra and pKa-determinations. The ionization sequences of the acidic hydrogens have been assigned based on these physical data .

LC–MS/MS Determination of Apigenin in Rat Plasma and Application to Pharmacokinetic Study

2020 ◽  
Vol 21 ◽  
Author(s):  
Shixing Zhu ◽  
Jiayuan Zhang ◽  
Zhihua Lv ◽  
Mingming Yu
Keyword(s):  
Formic Acid ◽  
Pharmacokinetic Study ◽  
Ammonium Acetate ◽  
Rat Plasma ◽  
Biological Properties ◽  
Plasma Samples ◽  
Supply Rate ◽  
Natural Plant ◽  
Ammonium Acetate Buffer

Background: Apigenin, a natural plant flavone, has been shown to possess a variety of biological properties. Objective: In this report, a highly selective and sensitive LC-MS/MS method was developed and validated for the determination of apigenin in rat plasma. Methods: Analysts were separated on the HSS T3 column (1.8 μm 2.1×100 mm) using acetonitrile and 0.1% formic acid in 2 mM ammonium acetate buffer at a supply rate of 0.200 mL/min as eluent in gradient model. Results: Plasma samples were treated by protein precipitation using acetonitrile for the recovery ranging from 86.5% to 90.1% for apigenin. The calibration curves followed linearity in the concentration range of 0.50-500 ng/mL. The inter-day and intra-day precisions at different QC levels within 13.1% and the accuracies ranged from -10.6% to 8.6%. Conclusion: The assay has been successfully applied to the pharmacokinetic study of apigenin in rats.

scholarly journals Metallkomplexe mit Tetrapyrrol-Liganden, XXXVIII [1]. Zur Kenntnis der Alkyl- und Arylimidovanadium(IV)-Porphyrine / Metal Complexes with Tetrapyrrole Ligands, XXXVIII [1]. On the Knowledge of Alkyl- and Arylimidovanadium(IV) Porphyrins

1985 ◽  
Vol 40 (10) ◽  
pp. 1362-1370 ◽  
Author(s):  
Johann W. Buchler ◽  
Stefan Pfeifer
Keyword(s):  
Mass Spectra ◽  
Nmr Spectra ◽  
Primary Amines ◽  
Reactive Intermediate ◽  
H Nmr ◽  
Vanadyl Complex ◽  
Elemental Analyses ◽  
Paramagnetic Metal ◽  
Paramagnetic Complexes ◽  
Proton Resonances

A series of novel alkyl or aryiimidovanadium(IV) 5,10,15,20-tetra(p-tolyl)porphyrinates, VNR(TTP) (4a-4g), is described. They are obtained from the vanadyl complex, VO(TTP) (2a) via the reactive intermediate VCl2(TTP) (3b) which undergoes aminolysis with the respective primary amines RNH2 (R = tBu, Ph, pTol, pClPh, pAnis, pBiph, ptBuPh)**. The formulae are proved by elemental analyses and mass spectra. The paramagnetic complexes are stable to water and may thus be purified by chromatography but are hydrolyzed to give 2 a on treatment with acetic acid. The UV/VIS and 1H NMR spectra of 4a-4g are of the same type as 2a, but the former are slightly hypsochromically shifted, and the latter do not show the proton resonances of the organylimide ligands due to the proximity of the paramagnetic metal center.

Charge Transfer Molecular Complexes of 4-(Dimethylamino)pyridine with Some Conventional and Unconventional Acceptors Involving Fluoroarenes

2006 ◽  
Vol 71 (9) ◽  
pp. 1359-1370 ◽  
Author(s):  
Usama M. Rabie
Keyword(s):  
Charge Transfer ◽  
Nmr Spectra ◽  
Molecular Complexes ◽  
Outer Sphere ◽  
Formation Constants ◽  
Stoichiometric Ratio ◽  
Spectral Bands ◽  
Elemental Analyses ◽  
Ct Complexes ◽  
Solid Complexes

Charge transfer (CT) complexes of 4-(dimethylamino)pyridine (DMAP) with iodine as a typical σ-type acceptor and with typical π-type acceptor, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), have been synthesized and characterized. Octafluorotoluene (OFT), octafluoronaphthalene (OFN), perfluorophenanthrene (PFP), and 2,3,5,6-tetrafluoropyridine-4-carbonitrile (TFP) were also used as acceptors for interaction with DMAP. Properties of such CT complexes were investigated by UV/VIS and IR spectra, and elemental analyses of the isolated complexes. The systems DMAP-iodine and DMAP-DDQ are characterized by formation of triiodide ions (I3-) and DDQ•- anion radicals, respectively, which is proposed to occur via initial formation of outer-sphere CT complexes. The systems (DMAP-OFT, DMAP-OFN, DMAP-PFP and DMAP-TFP) are characterized by the appearance of new UV/VIS spectral bands assigned as CT bands; they also furnished the corresponding solid complexes with the stoichiometric ratio 1:1. 1H and 19F NMR spectra were used on confirming the formation of the DMAP-PFP CT complexes. The formation constants (KCT) and molar absorption coefficients (εCT) of the latter complex were obtained.

scholarly journals Synthesis of new condensed coumarin derivatives

2007 ◽  
Vol 5 (1) ◽  
pp. 85-88 ◽  
Author(s):  
Stojadin Dekic ◽  
Vidoslav Dekic ◽  
Branimirka Vucic ◽  
Biljana Dekic ◽  
Milan Dekic
Keyword(s):  
Acid Hydrolysis ◽  
Nmr Spectra ◽  
Proton Nmr ◽  
Catalytic Amount ◽  
The Novel ◽  
Coumarin Derivatives ◽  
Elemental Analyses

Reactions of 4-chloro-2-oxo-2H-chromene-3-carbonitrile (1) with 4-methylpyridin- 2-ylamine (2) and 6-methoxy-benzothiazol-2-ylamine (3) in acetonitrile containing a catalytic amount of triethylamine gave the new coumarin derivatives 7-imino-10-methyl-7H- 5-oxa-7a,12-diaza-benzo[a]anthracen-6-one (4) and 7-imino-10-methoxy-7H-5-oxa-12- thia-7a,13-diaza-indeno[1,2-b]phenanthren-6-one (5) in 52 and 39% yields, respectively. The novel compounds were subjected to acid hydrolysis giving the corresponding oxoderivatives 10-methyl-5-oxa-7a,12-diaza-benzo[a]anthracene-6,7-dione (6) and 10- methoxy-5-oxa-12-thia-7a,13-diaza-indeno[1,2-b]phenanthrene-6,7-dione (7) in 64 and 58% yields, respectively. The structural assignments of the synthesized compounds were based on elemental analyses, IR and proton NMR spectra. .

N-Chlorsilyl-triorganophosphinimine, Darstellung und Eigenschaften / N-Chlorosilyl Triorganophosphine Imines, Preparation and Properties

1977 ◽  
Vol 32 (9) ◽  
pp. 961-966 ◽  
Author(s):  
Werner Wolfsberger
Keyword(s):  
Molecular Weight ◽  
Nmr Spectra ◽  
Elemental Analyses ◽  
New Compounds

A series of N-chlorosilyl triorganophosphine imines have been prepared by transsilylation reactions of the corresponding N-trimethylsilyl triorganophosphine imines with halosilanes. The new compounds were characterized by elemental analyses, molecular weight determinations, IR and 1H and 31P NMR spectra.

Studies on Ylides: Reactions of N -Pyridinium Phenancylides with α,β-Unsaturated Ketones, I

1974 ◽  
Vol 29 (7-8) ◽  
pp. 552-555 ◽  
Author(s):  
Purshottam S. Kendurkar ◽  
Ram S. Tewari
Keyword(s):  
Acetic Acid ◽  
Nmr Spectra ◽  
Ammonium Acetate ◽  
Ir And Nmr Spectra ◽  
Unsaturated Ketones

Reactions of N-pyridinium phenancylides with different a, β-unsaturated ketones give 2,4,6-triarylsubstituted pyridines, 2,6-diphenyl-4-(2-pyridyl) pyridines, 2-benzylidene-4,6-diphenyl pyridines and 2,4,6-triphenyl-3-bromopyridine. Ammonium acetate in acetic acid was used as cyclization agent. The structure of the products are supported by IR and NMR spectra.

Synthesis and magnetic properties of polymeric complexes containing ruthenium(II)-ruthenium(III) tetracarboxylato units linked by cyanato, thiocyanato, and selenocyanato ligands

2008 ◽  
Vol 62 (4) ◽  
Author(s):  
Makoto Handa ◽  
Hideaki Ishida ◽  
Kayoko Ito ◽  
Toshihiro Adachi ◽  
Takahisa Ikeue ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
1H Nmr ◽  
Nmr Spectra ◽  
Diffuse Reflectance ◽  
Magnetic Susceptibilities ◽  
Diffuse Reflectance Spectra ◽  
Main Species ◽  
Elemental Analyses ◽  
Polymeric Species ◽  
Polymeric Complexes

AbstractPolymeric complexes of ruthenium(II)-ruthenium(III) tetracarboxylato units linked by cyanato, thiocyanato, and selenocyanato ligands [Ru2{O2C(CH2)mCH3}4(L)]n (m = 0, 4–7; L = OCN−, SCN−, and SeCN−) were prepared and characterized based on the elemental analyses, IR, and diffuse reflectance spectra. Magnetic susceptibilities were measured at the temperature range of 4.5 K to 300 K, where the interdimer antiferromagnetic interactions were revealed. The strongest interaction was exhibited in case of m = 7 and L = OCN−. 1H-NMR spectra of [Ru{O2C(CH2)7CH3}4(SCN)]n in CD2Cl2 showed broad signals which can be ascribed to polymeric species, as the addition of tetrabutylammonium thiocyanate caused sharper signals due to the formation of [Ru2{O2C(CH2)7CH3}4(SCN)2]− adduct as the main species in the solution.

Reaction of Ester Ethoxycarbonylhydrazones with Aliphatic Diamines

1995 ◽  
Vol 60 (5) ◽  
pp. 903-909 ◽  
Author(s):  
Aykut A. Ikizler ◽  
Kemal Sancak
Keyword(s):  
Nmr Spectra ◽  
H Nmr ◽  
Elemental Analyses ◽  
Aliphatic Diamines

Reaction of esters of (N-ethoxycarbonyl)alkanehydrazonic acids with aliphatic diamines were prepared α,ω-bis(3-alkyl-4,5-dihydro-1H -1,2,4-triazol-5- one-4-yl)alkanes. All compounds were characterized by elemental analyses, IR and 1H NMR spectra.

Sign in / Sign up

Export Citation Format

Share Document