C[O:2][C:3]([C:5]1([N:13]([CH3:26])[C:14](=[O:25])[CH2:15][C:16]2[C:21]([CH3:22])=[CH:20][C:19]([CH3:23])=[CH:18][C:17]=2[CH3:24])[CH2:10][CH2:9][N:8]([O:11][CH3:12])[CH2:7][CH2:6]1)=O.C[O-].[Na+].[Cl-].[NH4+].Cl>CN(C)C=O>[OH:2][C:3]1[C:5]2([CH2:10][CH2:9][N:8]([O:11][CH3:12])[CH2:7][CH2:6]2)[N:13]([CH3:26])[C:14](=[O:25])[C:15]=1[C:16]1[C:21]([CH3:22])=[CH:20][C:19]([CH3:23])=[CH:18][C:17]=1[CH3:24]To a solution of 1-methoxy-4-{methyl-[2-(2,4,6-trimethyl-phenyl)-acetyl]amino}-piperidine-4-carboxylic acid methyl ester (85.0 g, 234.5 mmol) in dimethylformamide (800 ml) at 0° C. was added sodium methoxide (38.0 g, 703.5 mmol) in four portions and stirring continued at 0° C. for 30 minutes, then at room temperature for 1 hour. The reaction mixture was poured on ice and saturated aqueous ammonium chloride, acidified to pH 5-6 with concentrated HCl and thoroughly extracted with ethyl acetate. The combined organic layers were washed with water and brine, dried over sodium sulfate, concentrated and the residue dried in vacuo. Yield: 72.7 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. The spectral data of this crude material were identical to those described above under preparation example 1, step 1.
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