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Communication | Regular issue | Vol 20, No. 9, 1983, pp.1731-1735
Published online, 1st January, 1970
DOI: 10.3987/R-1983-09-1731
New Syntheses of Praziquantel: 2-(Cyclohexylcarbonyl)-1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a]isoquinolin-4-one

Daniel Frehel and Jean-Pierre Maffrand

*Linge Hémobiologie, Sanofi Recherche, 195 route d’Espagne, 31036 Toulouse, France


This paper describes two different synthetic pathways for praziquantel, a new broad spectrum schistosomicide and cestocide. Easy to apply on an industrial scale, they involve a selective reduction of 4-acyl-1-phenethylpiperazine-2,6-dione in 4-acyl-6-hydroxy-1-phenethylpiperazin-2 one, the cyclisation of which in acidic medium gives tricyclic compounds 2-acyl-1,2,3,6,7,11b-hexahydro-4H-pyrazin [2,1-a]isoquinolin-4-one.