Racemic Resolution of Praziquantel and Praziquanamine

 

RXN 003 - Resolution of rac-PZQamine with (+)-dibenzoyl-D-tartaric acid (MW10-6) to obtain S-(+)-PZQamine (MNR2-2)

See Synthesis of (+)-Dibenzoyl-D-tartaric acid - alternative route (MW10-6) Hydrolysis of rac-PZQ (MW2-14)

Hazard and Risk Assessment: As for MNR2-1

rac-PZQamine (1.0 g, 4.94 mmol) and (+)-dibenzoyl-D-tartaric acid. 2IPA (2.37 g, 4.94 mmol) was dissolved in a mixture of isopropanol (20 mL) and water (2 mL) by heating. The solution was allowed to cool to room temperature and stand overnight. The solid was then filtered and rinsed with IPA/water (5:1, 50 mL).

Crude salt (1.626 g)

The salt (1.626 g) was dissolved in NaOH solution (2M, 25 mL) and extracted with DCM (25 ml x 3). The organic fractions were combined, dried over magnesium sulphate, filtered and concentrated under reduced pressure to give a white solid (0.361 g, 1.78 mmol, 72 %).

MNR2-2 [α]D20 = +284° (c=1, DCM) ee 96 %

1H NMR

Product taken on and used is N-Cyclohexanoyl-protection of MNR2-2 to give S-PZQ (MNR1-2)

IR 

*Note, tartaric acid should have been recovered but was lost during a clean up.

Lab book page complete, MNR