A series of paddlewheel diruthenium(ii, ii) complexes with various fluorine-substituted benzoate ligands were isolated as THF adducts and structurally characterized: [Ru(2)(F(x)PhCO(2))(4)(THF)(2)] (F(x)PhCO(2)(-) = o-fluorobenzoate, o-F; m-fluorobenzoate, m-F; p-fluorobenzoate, p-F; 2,6-difluorobenzoate, 2,6-F(2); 3,4-difluorobenzoate, 3,4-F(2); 3,5-difluorobenzoate, 3,5-F(2); 2,3,4-trifluorob...

Second-order rate constants (kN) have been measured spectrophotometrically for the nucleophilic displacement reactions of 4-nitrophenyl X-substituted-cinnamates (4a-4e) and Y-substituted-phenyl cinnamates (5a-5e) with Z-substituted-phenoxide anions in 80 mol % H2O/20 mol % DMSO at 25.0 ± 0.1 C. The Hammett plot for the reactions of 4a-4e with 4-chlorophenoxide (4-ClPhO) consists of two intersec...

0040-4039/$ see front matter 2011 Elsevier Ltd. A doi:10.1016/j.tetlet.2011.11.097 ⇑ Corresponding author. Tel.: +381 11 3336738; fax E-mail address: [email protected] (B.J. Draku Rate constants for the esterification of eleven 2-[(carboxymethyl)sulfanyl]-4-oxo-4-arylbutanoic acids with diphenyldiazomethane in ethanol at 30 C were determined, and correlated with substituent constants using...

Negative-ion electrospray ionisation mass spectrometry with an anionic phosphine ligand enables detection of key intermediates in the Sonogashira reaction. MS/MS techniques are used to generate a Hammett plot for the key reductive elimination step.

Three series of thioglycosyl donors differing only in their respective aglycon substituents within each series have been prepared as representatives of typical glycosyl donors. The relative anomeric reactivities of these donors were quantified under competitive glycosylation conditions with various reaction time, promoters, solvents and acceptors. Over three orders of magnitude reactivity diffe...

C-K Wong, C J K Hammett, R The, J K French, W Gao, B J Webber, J M Elliott, A W Hamer, J A Ormiston, M W I Webster, R A H Stewart, R V Ameratunga, H D White . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

A series of five 3-nitroflavones were tested for their ability to inhibit the formation of colon aberrant crypt foci (ACF) induced by a s.c. injection of azoxymethane (C2H6N2O) in rats. Our aim was to relate the electron-donating effects of the 3-nitroflavones as characterized by their Hammett substitution constants with their efficacy in inhibiting ACF. In a first assay (initiation, protocol A...

Systematic studies on phenol derivatives facilitates an explanation of the enhancement or inhibition of the luminol-H2O2-horseradish peroxidase system chemiluminescence. Factors that govern the enhancement are the one-electron reduction potentials of the phenoxy radicals (PhO./PhOH) vs. luminol radicals (L./LH-) and the reaction rates of the phenol derivatives with the compounds of horseradish ...