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A theoretical investigation was carried out on the mechanism and regioselectivity of the [3 + 2] cycloaddition (32CA) reaction of benzoisothiazole-2,2-dioxide-3-ylidene with nitrone using Molecular Electron Density Theory through DFT calculations at B3LYP and wB97xD functionals with 6-31G(d,p) basis set in the gas phase and toluene. Hard and soft acids and bases principle, Parr functions, as well as potential energy surface analysis were utilized for studying the regio- and stereoselectivity of this reaction, and the obtained results are consistent with the experimental observations. The electron localization function analysis of the nitrone shows that there is a double bond between N and C in the absence of any carbenoid or pseudoradical center. Therefore, a zwitterionic structure for nitrone 2 can be suggested, expected that its 32CA reaction is zw-type. The noncovalent interactions topological analysis shows that the first sigma bond has been formed before reaching the TS, which is in line with a two-stage one-step mechanism. [ABSTRACT FROM AUTHOR]

1. Sex-related differences of long pelvic limb bones and serum bone metabolism indices were evaluated in 14-month-old female (N = 7) and male (N = 7) ostriches of similar body weights. 2. Densitometric parameters of femur, tibia and tarsometatarsus were determined using quantitative computed tomography (volumetric bone mineral density, calcium hydroxyapatite density and mean volumetric bone mineral density) and dual energy X-ray absorptiometry (bone mineral density and bone mineral content) methods. Geometrical parameters such as cortical bone area, cross-sectional area, second moment of inertia, mean relative wall thickness and cortical index were determined in the midshaft of bones. Mechanical properties of bones (maximum elastic strength and ultimate strength) were evaluated using three-point bending test. Serum concentrations of free amino acids, osteocalcin, N-terminal propeptide of type I procollagen, C-terminal telopeptides of type II collagen and total antioxidative capacity were also determined. 3. Bone weight and relative bone weight of all bones were significantly higher in males than in females. Significantly lower values of trabecular bone mineral density and calcium hydroxyapatite density were found in the trabecular bone of tibia in males. The highest number of the sex-related differences was observed in the tarsometatarsus where bone length, bone mineral content, cortical bone area, cross-sectional area and ultimate strength were higher in males. Serum concentrations of taurine, hydroxyproline, valine and isoleucine were significantly higher in males. 4. Higher loading of the tarsometatarsus in comparison to femur and tibia may be an important factor interacting with sex hormones in regulation of bone formation and mineralisation processes. Sex-related differences of bone properties were associated with increased serum concentration of selected amino acids in males. [ABSTRACT FROM AUTHOR]

The Kinugasa reaction between phthalimidoacetylene and cyclic nitrones derived from L-phenylglycine or L-serine and glyoxylic acid, catalyzed by copper(I) chloride in the presence of triethylamine, is reported. The acetylene molecule approaches the nitrone exclusively anti to the bulky substituent next to the nitrogen atom to provide the cis-substituted β-lactam ring preferentially. The six-membered oxazinone ring can be easily opened, the phthaloyl residue can be transformed into a Boc protecting group, and substituents at the C-4 carbon atom and the nitrogen atom of the β-lactam ring can be easily removed or transformed into groups suitable for further synthesis of a variety of monobactam structures. Selected synthesized compounds were evaluated for their biological activity, showing interesting properties. [ABSTRACT FROM AUTHOR]

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