microwave in glycosylation reaction: design, and synthesis of highly substituted nicotinonitrile nucleosides

An efficient and rapid regiospecific approach for the synthesis of cyclic and acyclic nucleosides of 2-oxonicotinonitriles was performed. whereas, glycosylation of 2-oxonicotinonitriles 1a, b with peracetylated sugars (namely, peracetylated glucose, galactose and ribose) under mwi tolerated exclusively the desired n-nucleosides 2a, b, 4a, b and 6a, b in significant yields (75–86%) and in short reaction time (5–7 min.). the same products were obtained under the conventional conditions, using halo-sugar with low yields in hard conditions. similarly, the acyclic nucleosides 8a, b and 9a, b were obtained under mwi and conventional conditions via reaction of 1a, b with 4-bromo butyl acetate and 2-acetoxyethoxymethyl bromide. finally, deprotection of the latter blocked n-nucleosides was performed via treatment with aqueous methanolic solution containing a catalytic amount of triethyl amine to give the desired free nucleosides 3a, b, 5a, b, 7a, b, 10a, b and 11a, b, respectively. the free nucleosides (3a, b, 5a, b, 7a, b and 11a, b) were evaluated against gram (+ ve) bacteria, gram (–ve) bacteria and one pathogenic fungi namely, aspergillus flavus. good results were obtained for compounds 7a, b and 11a, b compared with the used standard drugs (cefotaxime and dermatin).