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Abstract: The rearrangement rates of several di-, tri-, tetra- or penta-substituted Z-arylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole (1a–18a) into the relevant 2-aryl-4-benzoylamino-5-phenyl-1,2,3-triazoles (1b–18b) have been determined in 1:1 (v:v) dioxane/water in a wide range of pS+ (3.80–12.50) at different temperatures. The kinetic data obtained have been correlated with those previously collected for the rearrangement of ortho-, meta- and para-substituted Z-arylhydrazones (19a–38a) by means of an extension of the linear free-energy relationship (LFER) proposed by Fujita and Nishioka, thus considering steric (Es) and field (Fo) proximity effects in addition to the normal electronic effects (σo,m,p). Excellent correlation coefficients have been calculated (R≥0.999), with susceptibility constants (ρ, δ and f) close to those previously obtained for 19a–38a, when only excluding data for the 2,6-bis-ortho-substituted Z-arylhydrazones 11a and 16–18a, which show a reactivity much higher than foreseeable, evidencing the first case of ‘steric acceleration’ in mononuclear rearrangements of heterocycles. A rationale for such a behaviour is proposed. [Copyright &y& Elsevier]

We report a newly developed synthesis of a number of alditol thiacrowns using an eco-friendly and versatile two-step strategy: the regioselective thioallyletherification of a polyhydroxylated alditol followed by a ring closing metathesis using the Grubbs second generation catalyst. This approach allows a series of target thiacrown products to be obtained in acceptable to good yields, from the corresponding α,ω-dithioallylether alditol starting materials featuring either the xylo , ribo , threo , erythro , d - manno or d - gluco configurations. The per- O -acetylated d -mannitol dithioallyether 10 , easily obtained on a large scale using this approach, was selected for evaluation as both an antibacterial and an antioxidant. Although no antibacterial activity was observed for the bacterial strains investigated, compound 10 is shown to be an antioxidant, and able to quench hydrogen peroxide in a stoichiometric fashion. [ABSTRACT FROM AUTHOR]