The use of carbon-13 magnetic resonance chemical shifts and long-range 13C–1H coupling constants for assigning the site of glycosylation on nitrogen heterocycles

A series of v-triazolo[4,5-b]pyridine nucleosides, which are structurally related to the biologically active 8-azapurines, has been prepared. The use of natural abundance carbon-13 n.m.r. in establishing the site of ribosylation of the nucleoside 5-amino-3-(β-D-ribofuranosyl)-v-triazolo[4,5-b]pyridin-7-one (6) is reported. The potential diagnostic utility of long-range (two- and three-bond)13C–1H coupling constants as an aid in the unequivocal assignment of the site of ribosylation and other signals in the 13C n.m.r. spectrum are described.