The lactam ring of the parent praziquantel was opened through hot alkaline hydrolysis. The resultant open lactam form of praziquantel (OLF- PZQ) has been subjected to various functionalization and interconversions of the amino and carboxylic acid Это и многое другое вы найдете в книге PREPARATION OF SOME DERIVATIVES OF OPEN-LACTAM FORM OF PRAZIQUANTEL