Zhiling Cao

Copper-catalyzed aerobic oxidative synthesis of aryl nitriles from benzylic alcohols and aqueous ammonia

Copper-catalyzed direct conversion of benzylic alcohols to aryl nitriles was realized using NH3(aq.) as the nitrogen source, O2 as the oxidant and TEMPO as the co-catalyst. Furthermore, copper-catalyzed one-pot synthesis of primary aryl amides from alcohols was also achieved.

Synthesis of Dimethyl Aryl Acylsulfonium Bromides from Aryl Methyl Ketones in a DMSO-HBr System

A new, simplified method for the synthesis of dimethyl aryl acylsulfonium salts has been developed. A series of dimethyl aryl acylsulfonium bromides were prepared by the reaction of aryl methyl ketones with hydrobromic acid and dimethylsulfoxide (DMSO). This sulfonium salt confirms that bromine production and the bromination reaction take place in the DMSO-HBr oxidation system. What’s more, it is also a key intermediate for the synthesis of arylglyoxals.

Stereoselective Synthesis of Quercetin 3-O-Glycosides of 2-Amino-2-Deoxy-d-Glucose Under Phase Transfer Catalytic Conditions

GRAPHICAL ABSTRACT This article describes the stereoselective synthesis of quercetin 3-O-glycosides of 2-amino-2-deoxy-d-glucose. Efficient 1,2-trans-glycosylation of protected quercetin with N-acetyl-protected 2-amino-2-deoxy-d-glucose chloride was achieved under phase transfer catalytic conditions in a 0.15 M aqueous K2CO3/chloroform system using tetrabutylammonium bromide as the catalyst. On the contrary, glycosylation with the N-phthalimido-protected bromide donor under the same conditions was found to give predominantly 1,2-cis-glycoside product.

Copper-Catalyzed Synthesis of N-aryl-D-Glucosamines from Arylboronic Acids

A convenient catalytic protocol was developed to synthesize N-aryl-D-glucosamines from the corresponding arylboronic acids. C‒N cross-coupling between arylboronic acids and 1,3,4,6-tetra-O-benzyl-β-D-glucosamine was realized by copper catalyst under mild conditions. Subsequent deprotection of the benzyl ethers gave the N-arylation products, N-aryl-D-glucosamines.

Synthesis of 4-[4-(3-pyridinyl)imidazol-1-yl]-1-butylamine

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.

Synthesis of novel glycosyl 1,3,4-thiadiazole derivatives

A convenient and mild protocol for the synthesis of glycosyl 1,3,4-thiadiazole derivatives was developed, which involved the reaction of glycosyl isothiocyanate, hydrazine hydrate, and various aldehydes followed by oxidative cyclisation with ferric ammonium sulfate in methanol. 13 examples of different glycosyl 1,3,4-thiadiazole derivatives were prepared. Good yields (70–87%) have been achieved. The glycosyl 1,3,4-thiadiazole derivatives may find applications in medicinal chemistry and pharmaceutical industry.

A facile and stereoselective synthesis of 3,4,6-tri- O -acetyl-2-deoxy-2phthalimido-β-D-glucopyranosyl chloride

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.

Novel synthesis of telithromycin

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.