Wilfried Peters

The metabolism of leukotrienes in blood plasma studied by high-performance liquid chromatography

The metabolism of leukotrienes (B4, C4, D4, and E4) within human plasma was studied and a simple sample preparation is presented. It was demonstrated that leukotriene E4 and leukotriene B4 were stable during incubation at 37 degrees C using the in vitro system. In contrast, leukotriene C4 was metabolized by gamma-glutamyl transpeptidase activities into leukotriene D4 which was further metabolized by dipeptidase activities of plasma into leukotriene E4. The transition state inhibitor of gamma-glutamyl transpeptidase L-serine-borate decreased the metabolism of leukotriene C4 in plasma. Dilution of plasma demonstrated that the dipeptidase was more active compared to the gamma-glutamyl transpeptidase. The metabolizing activities of plasma were functionally characterized by fractionating the plasma proteins.

Tris(pyrazolyl)methanesulfonate (Tpms) − A Versatile Alternative to Tris(pyrazolyl)borate in Rhodium(I) Chemistry

Thallium(I) tris(pyrazol-1-yl)methanesulfonate (TlTpms) has been prepared as a new versatile precursor for Tpms complexes. TlTpms readily reacts with the rhodium(I) complexes [Rh(LL)Cl]2 [LL = (CO)2, cod, nbd] to give the corresponding TpmsRh(LL) complexes [LL = (CO)2 (2a), cod (3), and nbd (4)]. In solution, 2a reversibly forms the binuclear complex TpmsRh(µ-CO)3RhTpms (2b). 3 and 4 react with CO to form 2a. TpmsRh(CO)(PR3) complexes [PR3 = PPh3 (5a), PMe3 (5b), PCy3 (5d), P(Ph)2(PhSO3K) (5e)] have been obtained by reaction of 2a with the corresponding phosphanes. The solid-state structures of 2a, 3, 4, and 5a have been determined by X-ray analysis. 2a, 3, and 5a have square-planar geometries with the Tpms ligand coordinating in a κ2 mode. The non-coordinating pyrazole ring faces either away from (structure 2a) or towards the rhodium atom (structures 3 and 5a). 4 has a trigonal-bipyramidal coordination geometry with a genuine κ3-bonded Tpms ligand. The non-rigid behaviour of the (Tpms)rhodium complexes has been followed by variable-temperature NMR studies. IR studies on 2a and 5a−e show that Tpms is a weakly donating ligand, comparable to the Tp and Tp ligands. Compound 5e is soluble and stable in dilute acids, showing that Tpms, unlike the Tp ligand, is hydrolytically stable.

Nitrogen Tripod Ligand/Oxygen Tripod Ligand Indium(III) Complexes: The First Structurally Characterized Trofimenko−Kläui Complex [η5‐(C5H5)Co{P(OCH3)2(O)}3InHB(pz)3][InCl4] (pz = pyrazol‐1‐yl)

Indium(III) complexes [LRInTp*]X {LR = (cyclopentadienyl)tris[diorganylphosphi(ni)to-P]cobaltate(1−) [η5-(C5H5)Co{PR2(O)}3]−, R = OCH3, CH2CH3; Tp* = hydrotris(3,5dimethylpyrazol-1-yl)borate} have been prepared from [Tp*InCl2(NCCH3)] and AgLOMe or TlLEt. Alternatively, equilibration of a 1:1 mixture of the homoleptic complexes [In(LOMe)2][PF6] and [In(Tp)2][PF6] in aqueous methanol slowly yielded the heteroleptic indium(III) complex [LOMeInTp][PF6]. An X-ray crystal structure determination revealed a fac-N3O3 coordination sphere for the [LOMeInTp][InCl4] complex. These indium compounds represent the first structurally characterized complexes where the tripodal oxygen ligand LR and the tripodal nitrogen ligand Tp are coordinated to the same metal center. Indium(III) is classified as a class a, i.e. a hard metal ion, but it evidently prefers an antisymbiotic arrangement of ligands.

Structure determination of unusual mixed-ligand complexes [LOMeInTp]X (X = [InCl4]−, [PF6]−) in solution by 2D 1H NOESY NMR spectroscopy†

Indium complexes [LOMeInTp][InCl4] (4) and [LOMeInTp][PF6] (5) containing the tripodal nitrogen ligand Tp− {Tp− = hydrotris(pyrazol‐1‐yl)borate, [HB(pz)3]−} and the tripodal oxygen ligand LOMe− (LOMe− = (cyclopentadienyl)tris(dimethylphosphito‐P)cobaltate(1−), [η5‐(C5H5)CoP(O)R23]−) were synthesized in high yields. Compounds 4 and 5 are the first complexes with a fac‐N3O3 coordination bearing both Kläuis and Trofimenkos tripodal ligands. Their structure in solution was determined unambiguously by 2D 1H NOESY NMR spectroscopy. Copyright

Synthese von 3-Methylenmonosubstituierten-2-oxo-tetxahydrofuranen aus 3-Phosphonolactonen/Synthesis of 3-Methylenmonosubstituted-2-oxo-tetrahydrofurans from 3-Phosphonolactones

Abstract The synthesis of 3-methylenmonosubstituted-2-oxo-tetrahydrofurans 3 a-f from 3-phosphonolactones 1 a-b and the aldehyds 2a-d is described. 1H NMR spectra of the 3-methylenmonosubstituted-2-oxo-tetrahydrofurans are discussed.

Preparation, Properties and Complexation Behaviour of P,P-Di-tert. Butylphosphinothioic Amides

Abstract Starting from tBu2PCl, the title compounds tBu2P(S)NHR′ (R′= Me Et, iPr, tBu) may be easily prepared according to With R′=tBu the amine has to be substituted by its Li-salt [tBuNH]−Li+.

Neue Synthese von 6-Formyl-trans- 5.6-methanohexansäuremethylester / Novel Synthesis of Methyl 6 -Formyl-trans- 5.6-methanohexanoate

Methyl 7-oxo-5-trans-heptenoate reacts with diazomethane in the presence of Pd(CH3COO)2 in high yield to the cyclopropane aldehyde 1, an important intermediate in the 5,6-methanoleukotriene synthesis.

Reaktionen vinyloger Hydrazide mit Carbiminium-Verbindungen / Reactions of Vinylogous Hydrazides with Carbiminium Compounds

Vinylogous hydrazides of type 1 react with methyleniminium salts only in 2-position to form aminomethylated compounds 2·HX. The oxidation of 1 with Hg(II)-EDTA results in a twofold dehydrogenation to the lactams 3, which may be aminomethylated in 2-position. The methylpiperidine derivatives 4 and 5 with Hg(II)-EDTA yield in a monodehydrogenation cyclic iminium compounds. These are isolated as 6 · ClO4 and 7 · ClO4 respectively, and show an enolimine structure, which is not accessible to intramolecular aminoalkylation. With the 2-methylsubstituted enhydrazinones 11 methyleniminium salts cause an attack at 4-position, vinylogous to the carbonyl function, and produce the aminomethylated derivatives 13. Oxidation of 11 gives rise to the lactams 12, which are inert to Mannich reagents. The Mannich bases 2 undergo an amine elimination to form the pyrazolinium betaines 15. The aminomethylated lactams 20 show, in addition to amine eliminations, retro Mannich reactions and from the cleavage products methylenebis(lactam-enhydrazinones) 21 result. Formaldehyde and primary amines generate with 1 and 3 the tetrahydropyrimidine derivatives 24/25 and 22/23, respectively. Hexahydroacridinediones 27 are obtained from the reaction of 21 with formaldehyde and acetic acid.