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31st August 2011 @ 03:07
RXN 004 - Enantiopure S-PZQamine (MNR2-2) is converted to S-PZQ (MNR1-2).

Resolution of praziquanamine with (+)-dibenzoyl-D-tartaric acid to obtain S-(+)-PZQamine (MNR2-2)


Hazard and Risk Assessment:

As for MNR1-1

To a cooled solution of S-(-)Praziquanamine (MNR2-2, S-PZQamine, 0.30 g g, 1.48 mmol) in DCM (8 mL) at 0°C was added triethylamine (0.31 mL, 2.22 mmol) and cyclohexanecarbonyl chloride (0.22 mL, 1.63 mmol). The solution was stirred overnight at room temperature.

The solution was quenched with water (5 mL) and stirred for a further 30 minutes. The layers were separated and the organic layer was washed with saturated sodium carbonate solution (10 mL), 0.5 M HCl (10 mL) and brine (10 mL). Dried over magnesium sulfate, filtered and concentrated under reduced pressure. The remaining yellow oil was dried under high vacuum for 4 hours to give a foam which was dissolved in a mixture of acetone/hexane (15 mL, 1:1 mixture) and heated until dissolved. The solution was allowed to stand at room temperature over night and the crystals that were formed did not look clean but were filtered off and rinsed with a cold mixture of acetone/hexane. After washing the crystals very little remained. The washings were concentrated again and ran through a column (50% EtOAc/hexane) to give a clear oil that crystallized after 4 hours under high vacuum.

Clean fractions* 0.153 g, 0.49 mmol, 33%
[α]D20 = +117.1 (c = 1, EtOH) -> ee 86%

1H NMR - very poor resolution but this is standard

*product also co-eluted with a higher spot, these fractions kept to one side.

Lab book page complete, MNR
Linked Entries
Attached Files
MNR1-2 table.PNG