Design, Synthesis, and Antiviral Activity of Novel Ribonucleosides of 1,2,3-Triazolylbenzyl-aminophosphonates

Ouahrouch, Abdelaaziz; Taourirte, Moha; Schols, Dominique; Snoeck, Robert; Andrei, Graciela; Engels, Joachim W.; Lazrek, Hassan B.

Next, the 1,2,3-triazolyl-nucleosides were prepared using the 1,3-dipolar cycloaddition reaction. For this, the terminal alkynes 3a-j and b-azido-ribose [27] were coupled using the Cu alkyne-azide cycloaddition in basic medium (triethylamine) and the reaction was carried out under microwave irradiation [28] . Microwave heating has been shown to increase reaction yields and to speed up reaction time [29] , b-azido-ribose is slightly unstable under micro-wave conditions and was used in excess. The configuration at the anomeric carbon C1 0 is retained as it is present in the b-azido-ribose. The hydroxyl functions were protected by benzoyl groups prior to the CuAAC reaction in order to increase the solubility of the compounds. The structures of all compounds were confirmed on the basis of 1 H, 13 C NMR spectra as well as by high-resolution mass spectrometry. In the 1 H NMR spectra of the intermediates, the triazole proton appears as a singlet in the aromatic region while the anomeric proton appears as a multiplet around 6 ppm.