N-versus O-glycosylation of purine nucleosides

Abstract
Conditions for inducing 5′-O-benzylation and 5′-O-glycosylation in 2′,3′-O-isopropylidene nucleosides without concomitantly effecting N- or O-substitution in the heterocycle or loss of the ribose portion via sugar exchange, were evaluated and found: treatment of 2 with benzyl bromide/potassium t-butoxide in dioxane readily yielded the 5′-benzyl ether 7 (67 %), reaction of 2 with acetobromoglucose and silver perchlorate/silver carbonate in chloroform gave 8 (41 % ), which was converted into 5′-O-(β-D-glucosyl)-inosine 9 by deblocking. The preparation of N1- and O6-substituted benzyl and glucosyl nucleosides (3 – 6) is also described.