[C:1]([O:5][C:6](=[O:18])[C:7]1[CH:12]=[C:11]([CH:13]=[CH2:14])[N:10]=[C:9]([N:15]([CH3:17])[CH3:16])[CH:8]=1)([CH3:4])([CH3:3])[CH3:2]>CO.[Pd]>[C:1]([O:5][C:6](=[O:18])[C:7]1[CH:12]=[C:11]([CH2:13][CH3:14])[N:10]=[C:9]([N:15]([CH3:16])[CH3:17])[CH:8]=1)([CH3:3])([CH3:4])[CH3:2]To a solution of 2-dimethylamino-6-vinyl-isonicotinic acid tert-butyl ester (877 mg, 3.53 mmol) in methanol (15 mL), Pd/C (150 mg, 10% Pd) is added and the mixture is stirred under 2 atm of H2 at rt for 3 h. The catalyst is filtered off and the filtrate is evaporated to give crude 2-dimethylamino-6-ethyl-isonicotinic acid tert-butyl ester; LC-MS: tR=0.76 min, [M+1]+=251.10. This material is dissolved in 6 N aq. HCl (60 mL) and the mixture is stirred at 80° C. for 72 h before the solvent is evaporated. The crude product is purified by MPLC on RP-C18-silica gel to give 2-dimethylamino-6-ethyl-isonicotinic acid (332 mg) as an orange oil, LC-MS: tR=0.51 min, [M+1]+=195.10.
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