These newly created drugs are markedly improved analogs or derivatives of {HEAD ~ certain previously known fluorenone compounds} that were never commercialized or developed into {TAIL ~ medically useful treatments} 
These newly created drugs are markedly improved analogs or derivatives of { HEAD ~ certain previously known fluorenone compounds } that were never commercialized or developed into { TAIL ~ medically useful treatments }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL