Microbiological transformations—XII: Microbiological reduction of racemic 1-(2',2',3'-trimethyl-cyclopent-3'-en-1'-yl)propan-2-one and 1-(2',2',3'-trimethyl-cyclopent-3'-en-1'-yl)butan-2-one by rhodotorula mucilaginosa

The microbiological reduction of (±)-l-(2',2',3'-trimethylcyclopent-3'-en-l'-yl)-propan-2-one (4) and (±)-1-(2',2',3'-trimethylcyclopent-3'-en-l'-yl)-butan-2-one (5) by Rhodotorula mucilaginosa was investigated. Both enantiomers of 4 are reduced stereospecifically to corresponding alcohols; (+)-(2S, l'R)-(2',2',3'-trimethylcyclopent-3'-en-l'-yl)-propan-2-ol (6) and (-)-(2S,l'S)-(2',2',3'-trimethylcyclopent-3'-en-l'-yl)-propan-2-ol (7). p ]The substrate selectivity in the reduction of 5 was observed: R enantiomer of 5 yields stereospecifically (+)-(2S,1'R)-(2',2',3'-trimethylcyclopent-3'-en-l'-yl)-butan-2-ol (8) while S(-)5 remains unchanged.     

Thermodynamics of Cobalt(II) Complexation with 2-Hydroxypropylene-1,3-Diamine-N,N,N",N"-Tetraethanoic Acid

The stability constants of cobalt(II) hydroxypropylenediaminetetraacetates at 298.15 K with ionic strength (I) equal to 0.1, 0.5, and 1.0 (KNO₃) are determined using poteniometric and spectrophotometric methods. Heat effects for reactions of complex formation under the same conditions are measured using the direct calorimetric method. The standard thermodynamic parameters of the reactions under study are calculated.     

Influence of Mg2+ Ion on Thermodynamic Parameters of Gd3+ and Ho3+ Complexation with n-Butyric Acid in Aqueous Solutions

Thermodynamic parameters of complexation were determined from data of calorimetric titration of LnCl₃-Hbut-Mg²⁺ and LnCl₃-HBut systems (Hbut is n-butyric acid) at 298 K and ionic strength 1.0 mol/l KCl. The Mg²⁺ ions were found to influence thermodynamic parameters of the lanthanide ion complexation with HBut.     

2'-deoxyribonucleoside 3'-aryl phosphoranilidates: Key intermediates in the stereospecific synthesis of 2'-deoxyribonucleoside cyclic 3',5'-phosphorothioates and dinucleoside(3'→5')-phosphoranilidates

Phosphorylation of the 5'-O-monomethoxytrityl-2'-deoxyribonucleosides by means of aryl phosphoranilidochloridates gives the diastereoisomers of 5'-O-monomethoxytrityl-2'-deoxyribonucleoside 3'-aryl phosphoranilidates. Their separation can be performed by means of chromatographic techniques. They can be further converted to the 2'-deoxyribonucleoside cyclic 3'-5' phosphoranilidates, which are intermediates in the stereospecific synthesis of 2'-deoxyribonucleoside cyclic (3'-5')phosphorothioates of known absolute configuration at phosphorus.     

An efficient synthesis of certain 5-substituted-2'-deoxyuridine 3',5'-cyclic monophosphate p-o-alkyl(aralkyl) esters. The crystal and molecular structure of 5-IODO-2'-deoxyuridine 3',5'-cyclic monophosphate p-o-methyl ester with axial methoxy group

Some 5-alkyl- and 5-halogeno-2'-deoxyuridine 3',5'-cyclic mono- phosphate P-O-alkyl(aralkyl) esters have been prepared from the silver salts of the parent cyclic monophosphates and alkyl(aralkyl) iodides. The diastereomeric phosphotriesters have been characterized by spectroscopic methods. The crystal and molecular structure of 5-iodo-2'-deoxyuridine 3',5'-cyclic monophosphate P-O-methyl ester with axial methoxy group has been determined. We failed to obtain the desired triesters from the reactions of the cAMP silver salt with alkyl iodides, contrary to previous claims in the literature.     

水溶液中P(AM-co-PEBA)聚合物对Tb3＋离子荧光增强作用

考察了Tb3＋离子在模板法合成的疏水缔合水溶性聚合物聚丙烯酰胺/4-(ω-丙烯酰氧乙氧基)苯甲酸(P(AM-co-PEBA))溶液中的荧光增强行为. 在溶液中P(AM-co-PEBA)通过羧基的络合作用及疏水缔合作用, 改变了 Tb3＋离子所处微环境, 降低了Tb3＋离子络合水的个数, 提高了Tb3＋离子荧光强度. 聚合物中PEBA含量增加或PEBA以微嵌段结构存在, 这一微环境效应得到增强. 另一方面, 聚合物P(AM-co-PEBA)分子内具有紫外光捕获基团, 可通过“天线效应”与Tb3＋离子进行能量传递, 进一步提高了Tb3＋离子的荧光强度.     

Complex formation of zinc, cadmium and manganese(II) with 2-hydroxypropylene-1,3-diamine-N,N,N′,N′-tetraacetic acid

The stability constants of the complexes of 2-hydroxypropylene-1,3-diamine N,N,N′,N′-tetraacetic acid (H₄L) with Zn²⁺, Cd²⁺, and Mn²⁺ ions were determined by the potentiometric method on the background of KCl at 298.15 K and ionic strengths of 0.1, 0.5, and 1.0. The resulting data were extrapolated to the zero ionic strength by a one-parameter equation.     

Copper(II) Complexes of N,N′-Bis-βCarbamoylethyl) Ethylenediamine in Aqueous Solution

The interactions of the ligand N, N -bis-(β-carbamoylethyl)-ethylenediamine (BCEN) with copper (II) in aqueous solution have been investigated by potentiometric and spectrophotometric techniques. The two protonation constants of the ligand at 25° in 0.2 M NaNO₃are 10^5-51and 10^5-44 The quantitative equilibrium studies of the stepwise reactions which precede the formation of CuBCEN²⁺ and the Cu-O to Cu-N bond rearrangements at the two amide sites are described in detail. Electronic spectra of the copper (II) chelates formed are measured and discussed.     

荧光探针2-硼酸基苯甲醛-(2′-羟基-4′-磺酸基)萘腙的合成及对Pb~(2+)的识别

设计合成了2-硼酸基苯甲醛-(2′-羟基-4′-磺酸基)萘腙衍生物(2-BBHSNH),该化合物水溶性极好,识别体系不需任何有机介质。在pH=6.0的KH2PO4-NaOH缓冲溶液中,2-BBHSNH对Pb2+具有选择性识别作用,主客体分子间形成1∶1型的发光配合物。该配合物最大发射波长为568nm,稳定常数为4.3×104 L·mol~(-1)。荧光强度的变化值与Pb~(2+)浓度在5.0×10-7~1.0×10-4 mol·L~(-1)范围内呈现良好的线性关系,相关系数R=0.9983,检出限为9.7×10-8 mol·L~(-1)。将该方法用于环境水样中Pb2+的测定,回收率为111%~116%。     

Magnesium and Calcium Complexation with 2-Hydroxypropylene-1, 3-Diamine-N,N,N′,N′-Tetraacetic Acid

Stability constants and heats of formation of magnesium and calcium hydroxypropylenediaminetetraacetates are determined, and the standard thermodynamic characteristics of the complexation equilibria are estimated.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 3, 2005, pp. 375–378.Original Russian Text Copyright © 2005 by Gridchin, Kochergina, Vasil’ev, Pyreu.     

Studies on the syntheses of heterocyclic compounds—DCCLXII : Alternative synthesis of trans-3-(1'R*-hydroxyethyl)-4-(2',2'-dimethoxyethyl)-2-azetidinone,a synthetic intermediate of thienamycin

Synthesis of trans-3-(1'R^*-hydroxyethyl)-4-(2',2'-dimethoxyethyl)-2-azetidinone (5), an important intermediate for the synthesis of thienamycin (1), was investigated starting from the isoxazoline derivatives 3 and 9. The most effective method was catalytic hydrogenation of trans-4-t-butoxycarbonyl-3-(2,2'-dimethoxyethyl)-5-methyl-isoxazoline (9) with Adams catalyst in acetic acid, followed by trimethylsilylation of the resulting epimeric aminoesters 11A and B, cyclization with EtMgBr, and deblocking. Novel reductions of the isoxazolines with sodium borohydride and nickel chloride or with diborane followed by catalytic hydrogenation were also reported.     

Complexation of Gold(III) with Pyridoxal 5′-Phosphate-Derived Hydrazones in Aqueous Solution

Today, complexes of gold(I) and gold(III) are recognized as promising drugs for the treatment of bacterial infectious diseases and oncological diseases, respectively. It is of interest to broaden the area of potential use of gold(III) compounds to the pathogenic microorganism as well. The first step towards the development of new antibacterial drugs based on Au³⁺ complexes is the study of their stability in an aqueous solution. The present contribution reports on the investigation of gold(III) complexation with five hydrazones derived from a well-known biologically active compound, pyridoxal 5′-phosphate (one of the aldehyde forms of the B₆ vitamin). The complex formation in aqueous solutions was confirmed by mass spectrometry and fluorescent spectroscopy. The stoichiometric composition of the complexes formed and their stability constants were determined using a UV–Vis titration method. The complexes are quite stable at physiological values of pH, as the speciation diagrams show. The results of the paper are helpful for further studies of gold(III) complexes interaction with biomacromolecules.     

一种吲哚螺吡咯多取代杂环化合物的合成及其晶体结构

利用多组分1,3偶极环加成反应方法,合成了一种新的螺环结构1'-甲基-3'-吡啶甲酰基-4'-(2-噻吩基)螺[吲哚啉-3,2'-吡咯啉]-2-酮化合物,并对该化合物进行了红外光谱、核磁共振谱及X-射线单晶衍射表征.单晶衍射结果表明:该晶体属于三斜晶系,空间群为P-1,晶体参数为a=0.899 9(1)nm,b=0.914 4(1)nm,c=1.271 1(2)nm,α=92.852(1)°,β=107.305(2)°,γ=101.580(1)°.在分子晶体结构中,吡咯啉环采用了信封式构象,通过螺碳原子与吲哚啉环相连,形成刚性螺环结构,2个环接近垂直构型,其二面角为84.15(2)°.     

Complexation Kinetics of N‐Alkyl‐Substituted Diamino Diamides with Nickel (II) in Aqueous Solution

Equilibrium constants are deter mined for the protonation and metal complexation of the nickel(II) complexes with 4‐methyl‐4,7‐diazadecanediamide (4‐Me‐L‐2,2,2), 4,7‐dimethyl‐4,7‐diazadecanediamide (4,7‐N,N′‐Me₂‐L‐2,2,2), 4‐ethyl‐4,7‐diazadecanediamide (4‐Et‐L‐2,2,2), and 4‐methyl‐4,8‐ diazaundecane diamide (4‐Me‐L‐2,3,2), in 0.10 M KCl at 25.0°C. The formation kinetics of these nickel (II) complexes have been studied under the same conditions with use of the stopped‐flow technique. The possible path ways for the complexation reaction of nickel (II) with these ligands are discussed. The first metal‐nitrogen bond formation is proposed as the rate‐determining step for the reactions of nickel (II) with the unprotonated ligands; proton loss is the rate‐limiting step in the reactions of nickel (II) with the monoprotonated ligands. Similarly, in dissociation reactions of these nickel (II) complexes, the rate‐determining step for the water dissociation pathway is the break age of the second nickel‐nitrogen bond; the rate‐determining step for the proton‐assisted path way is the protonation of the released amino group. The important factors determining the reactivity of these complexes are considered. The kinetic results of the formation and dissociation reactions of these complexes are consistent with dissociative mechanism.     

四元轻稀土硝酸盐水溶液体系{H2O+La(NO3)3+Pr(NO3)3+Nd(NO3)3}的热力学研究

在298.15 K条件下, 利用等压法研究了四元轻稀土硝酸盐水溶液{H2O La(NO3)3 Pr(NO3)3 Nd(NO3)3}及其3个二元亚系{H2O La(NO3)3}, {H2O Pr(NO3)3}和{H2O Nd(NO3)3}的热力学性质. 以NaCl或CaCl2水溶液为参考溶液, 测定了不同水活度条件下该四元溶液的渗透系数及各溶质组元的活度系数. 实验结果表明, 上述四元系与其3个二元亚系之间存在简单共性, 在实验误差允许范围之内(|Δ|≤0.0010), 该四元系符合偏理想溶液模型.