4-amino-5-(methylthio)-9-(β-D-ribofuranosyl)pyrrolo<2,3-d:5,4-d'>dipyrimidine

5-(allylthio)-4-amino-9-(β-D-ribofuranosyl)pyrrolo<2,3-d:5,4-d'>dipyrimidine

4-amino-5-<(p-nitrobenzyl)thio>-9-(β-D-ribofuranosyl)pyrrolo<2,3-d:5,4-d'>dipyrimidine

4,5-diamino-9-(β-D-ribofuranosyl)pyrrolo<2,3-d:5,4-d'>dipyrimidine

4-amino-9-(β-D-ribofuranosyl)pyrrolo<2,3-d:5,4-d'>dipyrimidin-5-one