2-Thiocytosine333-49-3100 % similar Cytosine71-30-752 % similar 2-O-Methylcytosine3289-47-247 % similar 4,6-Diamino-2-mercaptopyrimidine1004-39-344 % similar 2-Imidazolidinethione872-35-539 % similar 2,4-Diaminopyrimidine156-81-037 % similar 4-Aminopyrimidine591-54-837 % similar 2-Amino-1,3,5-triazine-4,6-dithiol2770-75-434 % similar 3-Pyridazinamine5469-70-532 % similar 2,6-Diaminopyridine141-86-631 % similar 4-Amino-6-methylpyrimidine3435-28-730 % similar 2-Aminoquinoline580-22-330 % similar