2(1H)-Pyrimidinone, 1-beta-D-ribofuranosyl- 22756-84-9 3690-10-6 NSC 309132 Pyrimidin-2-one beta-D-ribofuranoside Pyrimidin-2-one beta-ribofuranoside Pyrimidin-2-one ribonucleoside Zebularine