Racemic Resolution of Praziquantel and Praziquanamine

 

Determination of the optical rotation of S-(+)-Praziquanamine in dependency of the ee

See also:

Hydrolysis of S-(+)-PZQ

Optical rotation of R-(-)-PZQ and S-(+)-PZQ

S-(+)-PZQamine:
m.p. 117-118°C (lit.[1] 117-119°).
[α]D20 = 296° (c=1, DCM) ([α]D20 for R-(-)-PZQamine: -306° (c=?, solvent=?) [2])


Determination of the optical rotation α in dependence of the ee (in %)

To a solution of S-(+)-PZQamine (c = 1, DCM) was added a solution of rac-PZQamine (c = 1, DCM) (vol/vol) to give a total volume of 1 mL.




Chart 1: Optical rotation α as a function of the ee

Small deviations due to the volatile solvent DCM.


Result:
Linear dependence of the optical rotation α of S-(+)-PZQamine on the ee (determined for a concentration c = 1 in DCM)

References:
[1] “Formation of Pyrazinoisoquinoline Ring System by the Tandem Amidoalkylation and N-Acyliminium Ion Cyclization: An Efficient Synthesis of Praziquantel”, J. H. Kim, Y. S. Lee, H. Park and C. S. Rim, Tetrahedron 1998, 54, 7395-7400.(DOI: doi:10.1016/S0040-4020(98)00401-3)

[2] “Pyrazinoisochinolin-Derivat“, R. Polke, F. Loebich, J. Seubert, H. Thomas and P. Andrews, German Patent Application (1975) DE 2,331,713.