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7th February 2011 @ 07:56
Experiments for the preperation of the N-benzoyl-protected derivative of the 'Ugi-intermediate' (MW36) via Ugi reaction

See also:
Optimizing conditions for the Ugi reaction (MW36-2 to MW36-5)
Preparation of the dimethoxy ‘Ugi-intermediate’ via Ugi reaction (MW40)

Ugi-approach to PZQ – testing the patented route to the ‘Ugi-intermediate’

Reaction Scheme correction

Hazard and Risk Assessment:
HRAF MW51.pdf

Start time: 5:10 PM 8/02/2011
End time: --

To a mixture of paraformaldehyde (114 mg, 3.81 mmol, 1.0 eq.), 2,2-dimethoxyethylamine (aminoacetaldehyde dimethyl acetal (401 mg, 3.81 mmol, 412 µL, 1.0 eq., M.W. 105.1 g/mol, d=0.973 g/mL) and benzoic acid (465 mg, 3.81 mmol, 1.0 eq., M.W. 122.12 g/mol) in methanol (2 mL) was added slowly 2-phenylethyl isocyanide (MW34-1) (500 mg, 3.81 mmol, 1.0 eq., M.W. 131.2, d=0.95 g/mL) and stirred at room temperature for XX (24) h.

Note: 2-phenylethyl isocyanide was purified before use by flush chromatography (silica gel, hexane:ethyl acetate = 4:1), because the pale brown oil became a dark brown gel while stored in the fridge for 6 month.

[1] “Novel Synthesis of Praziquantel“, A. Dömling, Patent Application 2009, WO 2009/11533(A1), Language: German.
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Attached Files
HRAF MW51.pdf
Reaction Scheme correction