Pictet-Spengler route to Praziquantel

 

START: 23/04/12
FINISH: 24/04/12




Hazard and Risk Assessment

Previous Experiments

Following Experiments

Chemical Information


Procedure
Dry dichloromethane (30 mL) was added under nitrogen to a flask containing Ytterbium(III) trifluromethanesulfonate (120.5 mg, 0.194 mmol, 0.2 equiv.) and well dried 3A powdered molecular sieves. Benzaldehyde (0.10 mL, 0.97 mmol, 1 equiv.) then 3,4-dimethoxyphenethylamine (0.16 mL, 0.97 mmol, 1 equiv.) were added to the mixture. The reaction mixture was stirred under nitrogen for 24 hours. The reaction was quenched by adding saturated sodium bicarbonate solution (30 mL). The organic fraction was separated, before the basic aqueous fraction was extracted with ethyl acetate (3 × 50 mL). The organic fractions were combined, dried over magnesium sulfate, filtered, then concentrated under reduced pressure to give crude KAB24-1 as a yellow oil (392 mg, 150%).
¹H-NMR of the crude product showed a mixture of the imine intermediate (identical to KAB19) and benzaldehyde (approximate ratio 1:0.15). The spectrum also contained a large water peak, which may account for the excess yield.


Monitoring the Reaction Progress by TLC


Summary and Conclusion

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NOTES Flask: 49.5964 g

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