ABSTRACT
In the title compound, C(14)H(14)BrNO(2)S, there are two similar non-equivalent mol-ecules in the asymmetric unit, displaying three chiral centres each. In the crystal structure, they are linked by inter-molecular N-Hâ¯O hydrogen bonds to form infinite chains, which are in turn connected by weak Brâ¯H and Sâ¯H inter-actions.
ABSTRACT
Regioselective N-beta-glucosamination of various unsubstituted or C4-, C5-, or C6-monosubstituted indolin-2-ones under phase transfer conditions was studied. The regioselectivity was unambiguously proved by (1)H NMR spectroscopy and X-ray analysis. The presence of a substituent at C7 of the aromatic ring leads to the formation of either a mixture of isomeric N-beta- and O-beta-D-glucosaminides or only oxazoline and/or 2-acetamidoglycal irrespective of the reaction conditions.
Subject(s)
Acetylglucosamine/chemical synthesis , Glycosides/chemical synthesis , Acetylglucosamine/chemistry , Crystallography, X-Ray , Glycosides/chemistry , Magnetic Resonance Spectroscopy , Molecular StructureABSTRACT
Glycosylation of methylbenzoxazolone-2 and benzothiazolone-2 with the full acetate of alpha-D-glucosaminyl chloride in the phase transfer systems investigated (solid-organic solvent and aqueous alkali-organic solvent) regioselectively leads to the corresponding N-beta-D-glucosaminides, which is proved by 1H NMR spectroscopy and X-ray analysis.
Subject(s)
Acetylglucosamine/chemical synthesis , Glycosides/chemistry , Acetylglucosamine/chemistry , Catalysis , Molecular Structure , StereoisomerismABSTRACT
This study provides details of the structure and interactions of Sarin and Soman with edge tetrahedral fragments of clay minerals. The adsorption mechanism of Sarin and Soman on these mineral fragments containing the Si(4+) and Al(3+) central cations was investigated. The calculations were performed using the B3LYP and MP2 levels of theory in conjunction with the 6-31G(d) basis set. The studied systems were fully optimized. Optimized geometries, adsorption energies, and Gibbs free energies of Sarin and Soman adsorption complexes were computed. The number and strength of formed intermolecular interactions have been analyzed using the AIM theory. The charge of the systems and a termination of the mineral fragment are the main contributing factors on the formation of intermolecular interactions in the studied systems. In the neutral complexes, Sarin and Soman is physisorbed on these mineral fragments due to the formation of C-H...O, and O-H...O hydrogen bonds. The chemical bond is formed between a phosphorus atom of Sarin and Soman and an oxygen atom of the -2 charged clusters containing an Al(3+) central cation and -1 charged complex containing a Si(4+) central cation (chemisorption). Sarin and Soman interact mostly in the same way with the same terminated edge mineral fragments containing different central cations. However, the interaction energies of the complexes with an Al(3+) central cation are larger than these values for the Si(4+) complexes. The interaction enthalpies of all studied systems corrected for the basis set superposition error were found to be negative. However, on the basis of the Gibbs free energy values, only strongly interacting complexes containing a charged edge mineral fragment with an Al(3+) central cation are stable at room temperature. We can conclude that Sarin and Soman will be adsorbed preferably on this type of edge mineral surfaces. Moreover, on the basis of the character of these edge surfaces, a tetrahedral edge mineral fragment can provide effective centers for the dissociation.
ABSTRACT
The use of crown ethers for a phase transfer-catalyzed synthesis of heteroaromatic glycosides of N-acetylglucosamine was studied. The solid-liquid system and the catalysis by 15-crown-5 were found to provide for both a 100% conversion of the alpha-D-glucosaminyl chloride peracetate and a high reaction rate. The interaction of alpha-D-glucosaminyl chloride peracetate and oxadiazole and triazole mercapto derivatives capable of thiol-thione tautomerism carried out at room temperature in acetonitrile in the presence of anhydrous potassium carbonate and crown ethers was shown to lead to both S- and N-glycosides. The structures of the compounds synthesized were confirmed by X-ray analysis and 13C and 1H NMR spectroscopy.
Subject(s)
Acetylglucosamine/chemistry , Crown Ethers/chemistry , Glycosides/chemical synthesis , Heterocyclic Compounds/chemical synthesis , Catalysis , Glycosides/chemistry , Glycosylation , Heterocyclic Compounds/chemistry , Magnetic Resonance Spectroscopy , Models, Molecular , Molecular Structure , StereoisomerismABSTRACT
The two bicyclic fragments of the title compound, C(22)H(20)N(4)O(4), are individually planar and are turned with respect to each other by 77.8 (2) degrees. The formation of intramolecular O-H.O and N-H.O hydrogen bonds causes considerable changes in the bond lengths within the amidopyridine fragment.