C([O:3][C:4](=[O:19])[C:5]1([CH3:18])[CH2:10][CH2:9][N:8]([C:11]([O:13][C:14]([CH3:17])([CH3:16])[CH3:15])=[O:12])[CH2:7][CH2:6]1)C.[OH-].[Na+]>C1COCC1.C(O)C.OS([O-])(=O)=O.[K+]>[C:14]([O:13][C:11]([N:8]1[CH2:9][CH2:10][C:5]([CH3:18])([C:4]([OH:19])=[O:3])[CH2:6][CH2:7]1)=[O:12])([CH3:17])([CH3:15])[CH3:16]
To a stirring solution of N-tert-butoxycarbonyl-4-methyl-isonipecotic acid ethyl ester (17.4 mmol, 4.73 g) in THF (50 mL) and ethanol (50 mL) was added 50% NaOH (50 mL) and the mixture heated to reflux overnight. The reaction was diluted with 10% KHSO4 (600 mL) and cone. H2 SO4 (5 mL) and extracted with ethyl acetate (2×250 mL). The organic layers were combined, washed with water (500 mL) and brine, dried over anhydrous sodium sulfate, and evaporated under reduced pressure. The residue was triturated with diethyl ether:hexanes and filtered to give 1.12 g of an orange solid. The filtrates were evaporated to give 2.71 g of the title compound as an orange solid.
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