Regioselective ribosylation conditions were established which gave bot
h -beta-D-ribofuranosyl)imidazo[4,5-b]quinolin-2-one (4) and -beta-D-r
ibofuranosyl)imidazo[4,5-b]quinolin-2-one (5), respectively, in high y
ield from 6,7-dichloroimidazo[4,5-b]quinolin-2-one (6). The distributi
ons of the sites of ribosylation under a variety of conditions are dis
cussed. (C) 1996 Elsevier Science Ltd.