Kinetics and mechanism of palladium(II) chloride catalysed oxidation of unsaturated acids by vanadium(V)

Summary The kinetics of the palladium(II) catalysed oxidation of acrylic, methacrylic and crotonic acid by vanadium(V), in acid medium at constant ionic strength exhibit zeroth order dependence on vanadium(V) and first order dependence on palladium(II) and the unsaturated acid. Complex formation between the palladium(II) species and the unsaturated acid, with possible exchange of chloride ion and hydrogen ion in two successive steps, was invoked. The reaction rate is determined by a rearrangement leading to elimination of chloride ion. A plausible mechanism is proposed.     

Liquid chromatographic method for the analysis of two plant based insecticide synergists dillapiole and dihydrodillapiole

A reversed-phase LC method for the determination of two plant based insecticide synergists dillapiole (5-allyl 6,7-dimethoxy 1,3-benzodioxole) and dihydrodillapiole (5-n-propyl 6,7-dimethoxy-1,3-benzodioxole) is reported. The resolution of dillapiole and dihydrodillapiole has been achieved on RP-18 column using methanol-water (90:10, v/v) as mobile phase and a photodiode array detector at 207 nm. The response was linear in the range of 25-250 microg. The developed isocratic RP-LC method was validated for specificity, linearity, precision, and accuracy. It has been applied for individual or simultaneous detection, monitoring and quantification of dillapiole and dihydrodillapiole from treated French bean Phaseolus sp.     

Synthesis of 2-substituted benzylidene-6-b-nitrothiazolo[3,2-α]benzimidazol-3(2H)ones as possible anticonvulsants

Several 2-substituted benzylidene-b-nitrothiazolo[3,2-α]benzimidazol-3(2H)ones were prepared by the condensation of 6-nitrothiazolo[3,2-α]benzimidazol-3(2H)one with suitable aryl aldehydes as possible anticonvulsants. Amongst these benzimidazoles, two compounds possessed anticonvulsant activity and provided 60% protection against pentylene-tetrazol-induced seizures in mice. J. Heterocyclic Chem., 14, 1093 (1977)     

The synthesis of enantiomerically pure 4-substituted [2.2]paracyclophane derivatives by sulfoxide-metal exchange

A general strategy for the synthesis of enantiomerically pure 4-substituted [2.2]paracyclophanes from a common sulfoxide precursor is described.     

Mixed valence copper(I)–copper(II) complexes of N,S donor ligands and their 7,7′,8,8′-tetracyanoquinodimethane derivatives

The reaction of the CuCl2·2H2O with the N,S donor ligands bis(o-aminobenzenethio)ethane, bis(o-aminoben-zenethio)propane and bis(o-aminobenzenethio)butane (abbreviated as eN2S2, pN2S2 and bN2S2, respectively) yielded mononuclear CuII complexes of stoichiometry Cu(L)Cl2 (L=eN2S2, pN2S2 or bN2S2). When the reactions were performed in the presence of 2,6–diacetylpyridine and NaClO4, binuclear mixed valence CuI–CuII complexes of stoichiometry [Cu2(L)][ClO4]3 (L=eN6S4, pN6S4 or bN6S4) were formed. Metatheses between the binuclear complexes and the lithium salt of 7,7,8,8-tetracyanoquinodimethane (TCNQ) yielded complexes of stoichiometry Cu2(L)(TCNQ)2 (L=eN6S4, pN6S4 or bN6S4). All of the complexes were characterised by analytical and spectroscopic techniques.     

Enhanced solubility and selective benzoylation of nucleosides in novel ionic liquid

Solubility and benzoylation study of both ribo- and deoxyribonucleosides is reported in a new ionic liquid MoeMIM·TFA; high selectivity for O-benzoylation is achieved.     

Cp*RhIII-Catalyzed Sterically Controlled C(sp3)−H Selective Mono- and Diarylation of 8-Methylquinolines with Organoborons**

Herein, the Rh^III-catalyzed selective monoarylation and diarylation (symmetrical and unsymmetrical) of 8-methylquinolines with organoboron reagents are disclosed. The selective monoarylation of primary C(sp³)−H bonds is achieved by using 7-substituted 8-methylquinolines or by changing the quantity of the aryl boronic acids. The method is also applicable for the arylation of 2-ethylpyridines, and the heteroarylation with thiophene-2-ylboronic acids. Symmetrical and unsymmetrical diarylation of 8-methylquinolines have been carried out in one-pot and sequential manner, respectively. Late-stage monoarylation of oxime derivatives and gram-scale synthesis of monoarylated products has also been carried out. A mechanistic study revealed that the current reaction is first order with respect to both reactants and a five-membered rhodacycle intermediate may be involved in the catalytic cycle.     

Copper(II)-mediated cross-coupling of arylboronic acids and 2(1H)-pyrazinones facilitated by microwave irradiation with simultaneous cooling

[reaction: see text] Optimized conditions for the decoration of the 2(1H)-pyrazinone scaffold were developed by applying the Chan-Lam protocol. It was demonstrated that this Cu(II)-mediated cross-coupling reaction resulted in significantly improved yields and rates when performed under microwave irradiation with simultaneous cooling at 0 degrees C, applying a mixture of bases Et(3)N/pyridine.