Synthesis and cytotoxic profile of glycosyl–triazole linked to 1,2,4-oxadiazole moiety at C-5 through a straight-chain carbon and oxygen atoms

The convergent synthesis of an unusual (but simple) class of compounds 5a–g has been achieved by the copper-catalyzed [3 + 2] cycloaddition reaction of 2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl azide 4 with propynyl 3-[3-(aryl)-1,2,4-oxadiazol-5-yl] propionates 3a–g. The formerly known azide 4 has been prepared according to the literature procedure; however, the synthesis of esters 3a–g is being reported for the first time. The infrared as well as 1H NMR spectra of all new products are in agreement with their proposed structures. By carrying out the nOe experiment of one of the final compounds 5a, we have been able to establish that only the 1,4-regioisomers have been formed in the cycloaddition reaction. All final products presented weak cytotoxic activity, but 5e and 5g had somewhat better behaviour showing 22–25% cell growth inhibition against two cell strains: NCI-H292 (lung carcinoma) and HEp-2 (larynx carcinoma).

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