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Acetylation of D-glucosamine catalysed by sulfuric acid and N-phthaloylation of the glucosyl acetate yielded 1,3,4,6-tetra-O-acetyl-2-deoxy-2-phthalimido-α-D-glucopyranose. This gave the corresponding pure β-glucosyl chloride upon treatment with PCl5-BF3. An anomeric chlorination with thionyl chloride combined with the Lewis acids (ZnCl2, SnCl4 and BiCl3) resulted in an α/β anomer mixture. [ABSTRACT FROM AUTHOR]

A novel synthesis route for telithromycin was developed based on a 11,12-cylic carbonate protection strategy to prevent formation of 9,12-hemiacetal by-product. Through a 11,12-carbonate-6-O-methylerythromycin intermediate, telithromycin was synthesised from 6-O-methylerythromycin in five steps with 33% overall yield. [ABSTRACT FROM AUTHOR]

4-[4-(3-pyridinyl)imidazol-1-yl]-1-butylamine, the side chain of telithromycin, is used for the synthesis of novel ketolide antibiotics. The key step in synthesising 4-[4-(3-pyridinyl)imidazol-1-yl]-1-butylamine involves the HBr-induced DMSO oxidation of 3-acetylpyridine to 3-pyridylglyoxal, which was not isolated but transformed directly into 4-(3-pyridyl)imidazole by a Debus reaction with ammonia and formaldehyde. [ABSTRACT FROM AUTHOR]