Racemic Resolution of Praziquantel and Praziquanamine

 

Testing a resolution method for (-)-PZQamine with (+)-di-p-anisoyl-D-tartaric acid following a resolution method for (+)-PZQamine with (-)-di-p-anisoyl-L-tartaric acid developed by Syncom B.V.

- see: Diastereomeric salt resolution of praziquanamine with (+)-di-p-anisoyl-D-tartaric acid (MW47-1)
and Synthesis of the resolving agent (+)-di-p-anisoyl-D-tartaric acid



Start time: 6:30 PM 30/09/2010
End time: 10:00 AM 5/10/2010

Procedure:
rac-Praziquanamine (505 mg, 2.50 mmol) and (+)-di-p-anisoyl-D-tartaric acid (1.07 g, 2.50 mmol) was dissolved in a mixture of isopropanol (10 mL) and water (2.0 mL) by heating. The solution was allowed to cool to room temperature over night.

- after 20 h at room temperature: little precipitate was formed
-> fridge at +5°C over 4 days: liquid was separated from the solid by pipetting off, precipitate was dried by a gentle stream of nitrogen: 1.72 g of a pale brown solid

113 mg of the salt liberated with 2 N NaOH, aq. solution extracted with DCM, dried over sodium sulfate, evaporated: 32 mg of a colorless solid
[a]D20 = -9° (c = 1, DCM).

Recrystallisation of the diastereomeric salt of
- 100 mg from 3.0 mL iPrOH/water (5:1)
- 103 mg from 2.5 mL iPrOH/water (2:1)