Effect of 1,4-Dioxane Solvent on ß-Glucuronidation Using Methyl 1,2,3,4-Tetra-O-acetyl-ß-D-glucuronate as the Glycosyl Donor.

A facile and selective ß-D-glucuronidation of alcohols, such as (-)-menthol, cholestanol, (+)- and (-)-borneols, and 2-adamantanol, using commercially available methyl 1,2,3,4-tetra-O-acetyl-ß-D-glucuronate as the glycosyl donor and trimethylsilyl bis(trifluoromethanesulfonyl)imide (Tf2NTMS) (0.5 equivalent) as the activator in 1,4-dioxane at 60 °C gave products in moderate yields. The addition of MS4A increased the ß : α ratios of D-glucuronides when cholestanol, (+)-borneol, and 2-adamantanol were used as the acceptor substrate.

Facile Preparation of L-Iduronic Acid and α-L-Iduronidation Using Methyl 1,2,3,4-Tetra-O-acetyl-α-L-iduronate as Glycosyl Donor.

Methyl 1,2,3,4-tetra-O-acetyl-α-L-iduronate was prepared from methyl 1,2,3,4-tetra-O-ß-D-glucuronate in two steps: Ferrier's photobromination and subsequent radical reduction with tris(trimethylsilyl)silane. The obtained methyl 1,2,3,4-tetra-O-acetyl-α-L-iduronate was a good glycosyl donor for the L-iduronidation when bis(trifluoromethanesulfonic)imide was employed as the activator. The reaction afforded the α-isomer as the major product, the configuration of which is the same as that of the L-iduronic acid unit in heparin and heparan sulfate.

A Facile α-Glucuronidation Using Methyl 1,2,3,4-Tetra-O-acetyl-D-glucuronate as Glycosyl Donor.

Some terpenyl 2,3,4-tri-O-acetyl-α-D-glucuronide methyl esters were facilely synthesized from commercially available methyl 1,2,3,4-tetra-O-acetyl-ß-D-glucuronate and terpenoid alcohols in the presence of bis(trifluoromethanesulfonyl)imide (Tf2NH) in dichloromethane (DCM) in good yields. The predominant α-selectivity at the anomer position is caused via transition state in which the neighboring group participation of the methoxycarbonyl group at C-6 stabilizes the oxonium intermediate by forming 1C4 conformation. The intermediate accelerates the glucuronidation reaction despite the use of the acetyl group, which is not a good activating group in general glycosylation reactions, as the activating group.

Synthesis and antiproliferative evaluation of 3,5-disubstituted 1,2,4-triazoles containing flurophenyl and trifluoromethanephenyl moieties.

An efficient 1,3-dipolar cycloaddition method was performed for the synthesis of a series of monofluoro- and trifluoromethane-3,5-disubstituted 1,2,4-triazoles. This efficient cycloaddition method was to react hydrazonoyl hydrochlorides with a series of aldehydes in the presence of NEt(3) as catalytic basic agent to provide the corresponding product in 28-94%. Their growth inhibitory results against cancer cells indicated that some of the fluorine- and trifluoromethane-containing compounds could effectively inhibit the growth of NCI-H226 and T-cell leukemia (Jurkat) cells. Among the compounds, trifluoromethane-containing 1,2,4-triazoles possessed the five-membered ring groups on the C-5 position of the triazolic ring, including cyclopentyl, 3-furyl, 3-thienyl, and 2-pyrrolyl, possessed the significant inhibitory activity for NCI-H226 cancer cells.

Synthesis and antiproliferative evaluation of N,N-disubstituted-N'-[1-aryl-1H-pyrazol-5-yl]-methnimidamides.

A series of N,N-disubstituted-N'-[1-aryl-1H-pyrazol-5-yl]-methnimidamides was synthesized by a newly developed microwave reaction and their antiproliferative activities were evaluated. Microwave irradiation of 5-amino-1,3-disubstituted pyrazoles with various amide solvents in the presence of POCl(3) provided the corresponding 2a-2k, 3a-3c, and 4a-4f in good to excellent yields. The obtained methnimidamides were tested against NCI-H661, NPC-TW01, and Jurkat cancer cell lines and the results indicated that compounds 2d and 2e were the most potent with IC(50) values in low micromolar range.