Reaction #657278

Reaction equation

4-benzyloxy-8-methoxy-1-methyl-3-(2,4,6-trimethyl-phenyl)-1,8-diaza-spiro[4.5]dec-3-en-2-one

→

4-hydroxy-8-methoxy-1-methyl-3-(2,4,6-trimethyl-phenyl)-1,8-diaza-spiro[4.5]dec-3-en-2-one

Solvents

methanol

water

Conditions

Workup

1. 1
   Filtrationthe reaction mixture was filtered
2. 2
   Concentrationconcentrated
3. 3
   workup.ADDITIONThe residue was diluted with ethyl acetate
4. 4
   Extractionextracted with saturated aqueous sodium carbonate under ice cooling
5. 5
   Temperaturewith cooling to pH 5-6 with an aqueous HCl solution
6. 6
   Extractionthoroughly extracted with ethyl acetate
7. 7
   WashThe combined organic layers were washed with brine
8. 8
   Dryingdried over sodium sulfate
9. 9
   Concentrationconcentrated

Procedure

To a solution of 4-benzyloxy-8-methoxy-1-methyl-3-(2,4,6-trimethyl-phenyl)-1,8-diaza-spiro[4.5]dec-3-en-2-one (22.6 g, 53.7 mmol) in methanol (226 ml) and water (22.6 ml) in a Parr shaker type hydrogenator was added 5% Pd/C (22.6 g). After hydrogenation under 4 bars H2 at 36° C. for 22 hours, the reaction mixture was filtered and concentrated. The residue was diluted with ethyl acetate and extracted with saturated aqueous sodium carbonate under ice cooling. The organic layer was discarded, the aqueous alkaline phase acidified with cooling to pH 5-6 with an aqueous HCl solution and thoroughly extracted with ethyl acetate. The combined organic layers were washed with brine, dried over sodium sulfate and concentrated. Yield: 13.0 g of 4-hydroxy-8-methoxy-1-methyl-3-(2,4,6-trimethyl-phenyl)-1,8-diaza-spiro[4.5]dec-3-en-2-one (title compound P2.2) as a solid, mp 239-241° C.

Source