Chiral dirhodium(II) carboxamidates are highly efficient catalysts for reactions between a variety of aldehydes and activated dienes. Catalyst loadings as low at 0.01 mol % have been realized with enantioselectivities up to 97%. Kinetic investigations reveal a pronounced electronic influence on the rate of the hetero-Diels-Alder reaction with a Hammett rho value of +1.9 (versus sigma(+)). Inhib...

The relative rate constants for the Rh(II)-mediated diazo decomposition of a series of para- or meta-substituted diazophenylacetates were measured through intermolecular competition. The kinetic data were further subjected to Hammett correlation analysis and were found to have better linear correlation with sigma(+). Reaction constants for four Rh(II) catalysts have been obtained, Rh(2)(OAc)(4)...

-The hydrolysis of several ring substituted methyl benzoates was investigated in aqueous solution over a pH range of 3-10. Both the pH dependence (at pH > 5) and the variation of hydrolysis rates with ring substitution are consistent with a mechanism involving the addition of hydroxide ion to the ester carbonyl group. Extrapolation of the rate data to a pH and temperature that would be consiste...

Density function theory with B3LYP parameterization and 6-31++G(d,p) basis set has been used to investigate the structure and stability of many mono-substituted naphthalene molecules. The Molecular Electrostatic Surface Potential (MESP) topography for all the mono-substituted naphthalene molecules was obtained. It is shown that the nature of the substituent and its orientation in the molecule p...

A series of new 8-arylhydrazono-2-(benzylsulfanyl)-7H-purin-6-ones 6 were synthesized, their electronic absorption spectra in different organic solvents of varying polarities were investigated and their acid dissociation constants in both the ground and excited states were determined spectrophotometrically. The tautomeric structures of such products were elucidated by spectral analyses and corr...

Strain-promoted cycloadditions of cyclic nitrones with biaryl-aza-cyclooctynone (BARAC) proceed with rate constants up to 47.3 M(-1) s(-1), this corresponds to a 47-fold rate enhancement relative to reaction of BARAC with benzyl azide and a 14-fold enhancement over previously reported strain promoted alkyne-nitrone cycloadditions (SPANC). Studies of the SPANC reaction using the linear free ener...

In situ activation of 3-arylpropiolic acids with T3P® (n-propylphosphonic acid anhydride) initiates a domino reaction furnishing 4-arylnaphtho[2,3-c]furan-1,3-diones in excellent yields. Upon employing these anhydrides as reactive intermediates blue-luminescent 4-aryl-1H-benzo[f]isoindole-1,3(2H)-diones are formed by consecutive pseudo three-component syntheses in a one-pot fashion. The Stokes ...

A self-promoted glycosylation method for the stereoselective formation of β-glucosides from a substrate library glycosyl trichloroacetimidate donors and acceptors is presented. The simple two-component reaction takes place at elevated temperatures, without addition any additives or catalysts. After basic workup, N-glycosides were obtained in good yields with high β-selectivity hence this allows...

4-Amino-4'-substituted biphenyls and 4-aminostilbenes substituted in the 3' or 4' position were studied for their in vitro and in vivo genotoxicity. The in vitro mutagenicity of the biphenyls with and without S9 activation was established with Salmonella strains TA98 and TA100 and that of the stilbenes with the same strains plus TA98/1,8-DNP6. The in vivo genotoxicity assay with both series of ...