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Over the last few decades many carbohydrate embedded macrocycles have drawn the attention of synthetic organic chemists because of their interesting chemical and biological properties. Suitably placed chiral 3- and 5-hydroxyl groups of 1,2-O-(1-methylethylidene)-a-D-xylofuranose, derived from inexpensive D-glucose, have been judiciously exploited to generate different non-natural C2-symmetric carbohydrate embedded macrocycles. Different symmetric aromatic and aliphatic hydrophobic spacers have been introduced between highly functionalized cluster of carbohydrate chiral centres through different intra- and intermolecular nucleophilic substitution and ring closing metathesis (RCM) for synthesis of 17 to 24 membered C2-symmetric macrocycles. [ABSTRACT FROM AUTHOR]

In this work, we are interested in the synthesis of new N-glucosyl 1,4-benzothiazin-3-ones by grafting 5,6-anhydro-3-O-alkyl-1,2-O-isopropylidene-α-D-glucofuranoses onto (Z)-2-benzylidene-3,4-dihydro-2H-1,4-benzothiazin-3-one 1. Deprotection of compounds 3a-c was performed in the mixture CF3COOH-H2O (9/1: v/v) leading to the corresponding compounds 4a-c with good yields. The structures of the synthesized compounds have been characterized using 1H NMR and 13C NMR. Compounds 3a-c and 4a-c were subjected to the evaluation of antibacterial activity. Some compounds tested showed significant activity.

The effect of different leaving groups on the substitution versus elimination outcomes with C-5 d-glucose derivatives was investigated. The stereochemical configurations of 3-O-benzyl-1,2-O-isopropylidene-5-O-methanesulfonyl-6-O-triphenylmethyl-α-d-glucofuranose, C36H38O8S (3) [systematic name: 1-[(3aR,5R,6S,6aR)-6-benzyloxy-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)-2-(trityloxy)ethyl methanesulfonate], a stable intermediate, and 5-azido-3-O-benzyl-5-deoxy-1,2-O-isopropylidene-6-O-triphenylmethyl-β-l-idofuranose, C35H35N3O5 (4) [systematic name: (3aR,5S,6S,6aR)-5-[1-azido-2-(trityloxy)ethyl]-6-benzyloxy-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxole], a substitution product, were examined and the inversion of configuration for the azido group on C-5 in 4 was confirmed. The absolute structures of the molecules in the crystals of both compounds were confirmed by resonant scattering. In the crystal of 3, neighbouring molecules are linked by C—H...O hydrogen bonds, forming chains along the b-axis direction. The chains are linked by C—H...π interactions, forming layers parallel to the ab plane. In the crystal of 4, molecules are also linked by C—H...O hydrogen bonds, forming this time helices along the a-axis direction. The helices are linked by a number of C—H...π interactions, forming a supramolecular framework.

Aldohexose, such as d-glucose, d-galactose or d-mannose, reacted with acetone to give the following O-isopropylidene derivatives: 1,2;5,6-di-O-isopropylidene- d-glucofuranose (IA), 1,2;3,4-di-O-isopropylidene- d-galactopyranose (IB) or 2,3;5,6-di-O-isopropylidene-D-mannofuranose (IC). The O-isopropylidene derivative (IA∼IC) reacted with alkyl/alkenyl halogenide to yield aldohexose ether compounds containing di-O-isopropylidene group, 3-O-alkyl-1,2;5,6-di-O-isopropylidene- d-glucofuranose (II), 6-O-alkyl-1,2;3,4-di-O-isopropylidene- d-galactopyranose (III) or 1-O-alkyl-2,3;5,6-di-O-isopropylidene- d-mannofuranoside (IV), in good yields. The Williamson ether synthesis was carried out using phase-transfer catalysis (PTC). The derived aldohexose alkyl ether containing di-O-isopropylidene group was hydrolyzed to give 3-O-alkyl-1,2-O-isopropylidene- d-glucofuranose (V) as a partial hydrolysis product; the complete hydrolysis of I∼IV gave, as expected, 3-O-alkyl-glucopyranose (VI), 6-O-alkyl-galactopyranose (VII) or 1-O-alkyl-mannofuranoside (VIII). Further alkylation of (V) with Mel under PTC and subsequent acid hydrolysis gave 3-O-alkyl-5,6-di-O-methyl- d-glucofuranose (X). Methanolysis of III with catalytic amounts of HSO gave 1-O-methyl-6-O-alkyl- d-galactofuranoside (XI). The elucidation of the galactofuranoside skeleton of (XI) was determined by means of itsC nuclear magnetic resonance spectra. The O-alkyl aldohexoses, e.g., X and XI, were evaluated and found to be emulsifiers. [ABSTRACT FROM AUTHOR]