The -c(=x)- Is Part Of A -c(=x)x- Group, Wherein The X's Are The Same Or Diverse Chalcogens (e.g., Pyrrole-3-carboxylic Acid, Etc.) Patents (Class 548/531)
- Additional -C(=X) bonded directly to the five-membered hetero ring (e.g., N n-butyryl-L-proline, etc.) (Class 548/533)
- Chalcogen bonded directly to the other ring carbon which is adjacent to the ring nitrogen of the five-membered hetero ring (e.g., 2-pyrrolidone-5 carboxylic acid, etc.) (Class 548/534)
- The five-membered hetero ring is further unsubstituted or alkyl substituted only (e.g., proline, etc.) (Class 548/535)