DEFINITIVE SOLUTION STRUCTURES FOR THE 6-FORMYLATED VERSIONS OF 1-(BETA-D-RIBOFURANOSYL)-, 1-(2'-DEOXY-BETA-D-RIBOFURANOSYL)-, AND 1-BETA-D-ARABINOFURANOSYLURACIL, AND OF THYMIDINE

ROESY and NOESY NMR spectroscopic analyses of the ribofuranosyl (la), 2'-deoxyribofuranosyl (Ib), and arabinofuranosyl (Ic) derivatives of 6 -formyluracil in (CD3)(2)SO and D2O solutions have established that ea ch exclusive 7,O5'-cyclic hemiacetal diastereomer of la,b and the majo r 7,O2'-cyclic hemiacetal diastereomer of Ic possess the 7R configurat ion. In addition, (7R)-1c has been shown to be thermodynamically more stable than (7S)-1c, contrary to our previous indication. A new, highe r yielding synthetic route to in has been developed, Ib has been obtai ned for the first time in crystalline form, the route to Ic has been m odified to better accommodate large scale preparations, and a new, fou rth member of this class, 6-formylthymidine (Id), has been synthesized and its solution structures in (CD3)(2)SO, D2O, and CD3OD have been d etermined. Antitumor and antiviral evaluations of la-e have revealed n o significant levels of activity.