Enantioselective Hydrogenation of dehydro-PZQ and derivatives

 

Synthesis of rac-PZQamine by an acidic hydrolysis of rac-PZQ



See also:
Hydrolysis of rac-PZQ (MW2-14)
Hydrolysis of rac-PZQ (MW2-13)
Optimizing the acid cleavage conditions II

Hazard and Risk Assessment:
Data: HIRAC MW2

Start time: 5:00 PM 13/04/2011
End time: 10:00 AM 14/04/2011

Procedure:
rac-PZQ (20.0 g, 64.0 mmol, M.W. 312.4 g/mol) was dissolved in a mixture of EtOH (150 mL) and 1N HCl (600 mL, 53.0 mL of 11.3 N HCl solution (35%) in 547 mL water) and heated to reflux for 17 h. Reaction monitored by TLC showed a complete consumption of PZQ (TLC, ethyl acetate, Rf ~0.5 for PZQ).

Work-up:
Solution was cooled to room temperature, washed with EtOAc (4 times 15 mL), basified with NaOH solution (5 N) to ph 12, extracted with DCM (5 x 30 mL), washed with brine, dried over NaSO4, evaporated under reduced pressure.
- the pale yellow oil became a solid after 1 h under high vac

Yield:
11.0 g (54.5 mmol, 85%) colourless solid (turning pale red/orange after a few hours at r.t.)
[M.W. = 202.3 g/mol]