Carbon Dioxide → 4-{[(Tert-butoxy)carbonyl]amino}pyridine-3-carboxylic acid

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

n-Buli (1.6 M soln, 155 mL, 249 mmol) was added to a stirred solution of TMEDA (37.36 mL, 249 mmol) in THF at −40° C. The solution was allowed to come at room temperature over 10 min and stirred for another 10 min. The solution was cooled to −78° C. A solution of pyridine-4-yl-carbamic acid-tert-butyl ester (117) (22 g, 113.26 mmol) in THF was added slowly. The solution was allowed to come at room temperature within 3 h. After stirring at room temperature for 15 min the solution was again cooled to −78° C. and a freshly crushed dry ice was added. The solution was allowed to come at room temperature, stirred for 30 min and poured into ice cold 10% NH4Cl solution. The solution was basified by 1N NaOH solution and washed by dichloromethane. The pH of aqueous phase was adjusted to 4 by cold 10% HCl solution. The solids formed were filtered, washed by water and dried under vacuum at room temperature to yield 16.3 g (30%) 4-tert-butoxycarbonylamino-nicotinic acid (118) as white solids. MP: 260° C.; 1H-NMR (DMSO-d6): δ 1.49 (s, 9H), 8.23 (d, J=6.0 Hz, 1H), 8.55 (d, J=6.0 Hz, 1H), 8.96 (s, 1H); EIMS m/z 238 (M+1).

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