4-Amino-1-(β-D-ribofuranosyl) quinazolin-2-one (3) was prepared by a direct glycosylation of 4-aminoquinazolin-2-one (7) using the Vorbruggen's silylation method and provided exclusively the β-anomer. This quinazoline nucleoside and its 2′, 3′-O-isopropylidene derivative (9) did not undergo the coupling reaction with dialkyl disulfides in the presence of tri-n-butylphosphine unless their 4-amino groups were protected by N, N- ...
