Gewebstypisierung bei Organtransplantationen

Ohne Zusammenfassung

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Tissue typing in organ transplantations

     

A carbocationic route to 3-substituted 1,4-cycloheptadienes

The Lewis acid catalysed reaction of 5-chloro-1, 3-cycloheptadiene 4 with silyl enol ethers yields -cycloheptadienyl substituted carbonyl compounds in high yield. Since 4 is easily prepared from cycloheptatriene, and the cycloheptadienyl cation 3 is preferably attacked at 3-position, this reaction opens an efficient access to 3-substituted 1,4-cycloheptadienes.     

Quantification of the electrophilicities of dithiocarbenium ions

The reactions of the dithio substituted carbenium ions 2a-c with allylsilanes, allylstannanes (3), and silylated enol ethers (4) which yield dithioacetal protected β, ψ-unsaturated carbonyl compounds (7) and selectively protected 1,3-dicarbonyl compounds (8), have been studied kinetically. The second-order rate constants have been used to determine the electrophilicity parameters for the [1,3]dithiolan-2-ylium ion 2a (E=?6.25) and the [1,3]dithian-2-ylium ions 2b (E=?6.82) and 2c (E=?2.17). It is shown how these parameters can be used to predict the electrophilic potential of 2a-c.     

Transition Metal Complexes of Cyanoisocyanoarenes as Building Blocks for One-, Two-, and Three-Dimensional Molecular Solids

The complexes trans-[MI(2)(CNC(6)H(4)-CN-4)(2)], (M = Pd and Pt), trans-[FeI(2)L(4)] (L = CNC(6)H(4)-CN-4 and CNC(6)H(2)-Me(2)-2,6-CN-4), and [Mn(CNC(6)H(4)-CN-4)(6)][SO(3)CF(3)] were prepared. The compounds are thermally stable up to 230 degrees C or higher. The molecular structure of trans-[FeI(2)(CNC(6)H(4)-CN-4)(4)] was determined by X-ray crystallography: monoclinic, space group P2(1)/n, a = 11.570(2) ?, b = 10.1052(8) ?, c = 28.138(7) ?, beta = 92.034(9) degrees, Z = 4, 3464 unique reflections, R = 0.074, R(w) = 0.089. The complexes contain the peripheral cyano groups in linear, planar, and octahedral dispositions, respectively. Solids were obtained by combining solutions of [PdI(2)(CNC(6)H(4)-CN-4)(2)] and [Cu(hfacac)(2)], [FeI(2)(CNC(6)H(4)-CN-4)(4)] and AgSO(3)CF(3), [FeI(2)(CNC(6)H(2)-Me(2)-2,6-CN-4)(4)] and [Rh(2)(O(2)CCF(3))(4)], and [Mn(CNC(6)H(4)-CN-4)(6)][SO(3)CF(3)] and [Rh(2)(O(2)CCF(3))(4)]. [PdI(2)(CNC(6)H(4)-CN-4)(2)] and [Cu(hfacac)(2)] in a ratio of 1:2 form a crystalline, one-dimensional solid: monoclinic, space group P2(1)/c, a = 8.317(2) ?, b = 13.541(1) ?, c = 22.568(5) ?, beta = 100.45(1) degrees, Z = 2, 3279 unique reflections, R = 0.037, R(w) = 0.047.     

Micropreparative fractionation of DNA fragments on metathesis-based monoliths: influence of stoichiometry on separation

New antibiotics were recently developed, among which are the (fluoro)quinolones. This paper presents an analytical method which allows the determination of 11 (fluoro)quinolones in swine kidneys: norfloxacin, ofloxacin, cinoxacin, oxolinic acid, nalidixic acid, flumequine, enrofloxacin, enoxacin, ciprofloxacin, danofloxacin and marbofloxacin. The procedure involves a rapid and efficient pre-treatment by solid-phase extraction (recoveries 83-98%), followed by the sensitive and selective determination of all compounds in a single run using LC-ESI-MS-MS. Multiple reaction monitoring (MRM) was used for selective detection of each (fluoro)quinolone. Quinine was selected as internal standard. The accuracy of the method, expressed as recovery, was between 89 and 109%; the repeatability had a maximum RSD lower than 15%. The limits of detection (LOD) were much lower than the respective Maximum Residue Limits (MRL)/4.     

Scales of Nucleophilicity and Electrophilicity: A System for Ordering Polar Organic and Organometallic Reactions

Contrary to widely held opinion, for many reactions in organic and organometallic chemistry it is possible to define nucleophilicity and electrophilicity parameters that are independent of the reaction partners. This phenomenon, discovered by Ritchie during the early 1970s for reactions of highly stabilized carbenium and diazonium ions with n-nucleophiles, also occurs with reactions of carbenium ions with aliphatic and aromatic π-electron systems and in hydride transfer reactions. With the aid of the scales of nucleophilicity and electrophilicity set out here, which extend over eighteen orders of magnitude, forecasts can be made about the feasibility and rate of a given CC bond formation, ionic reduction, or diazo coupling. Linkage with the reactivity scales of Ritchie and Sweigart/Kane-Maguire enables a unified treatment of a large number of polar reactions.