20191
Synthesis and Structure - Activity Relationships of 5 , 6 , 7 - Substituted Pyrazolopyrimidines : Discovery of a Novel TSPO PET Ligand for Cancer Imaging .
 Chemical: 5 , 6 , 7 - Substituted Pyrazolopyrimidines
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: 5 , 6 , 7 - Substituted Pyrazolopyrimidines