Compounds containing five-membered heteroaromatic rings containing two carbons, two nitrogens, and one oxygen atom which exist in various regioisomeric forms.
Oxadiazole
D011720
Pyrazoles
Azoles of two nitrogens at the 1,2 positions, next to each other, in contrast with IMIDAZOLES in which they are at the 1,3 positions.
D012263
Ribonucleosides
Nucleosides in which the purine or pyrimidine base is combined with ribose. (Dorland, 28th ed)