反应详情

To a stirred mixture of 6-tert-butoxycarbonylnicotinic acid (1.9 g, 8.51 mmol) and triethylamine (1.17 g, 11.49 mmol) in tert-BuOH (30 ml) and toluene (30 ml) was added a solution of diphenyl phosphoryl azide (2.93 g, 10.64 mmol) in toluene (3 ml) at room temperature. The resulting mixture was then heated at reflux for 5 hr. After cooling, ice and 1N HCl (5 ml) was added to the mixture and extracted with toluene. The extracts were washed with brine, dried over Na2SO4, and evaporated. The residue was chromatographed on silica gel (50 ml) with toluene-EtOAc (5:1, v/v) as eluent to give tert-butyl 5-tert-butoxycarbonylamino-2-pyridinecarboxylate (1.9 g, 76%) as a gum. 1H-NMR (CDCl3) δ1.53 (s, 9 H), 1.63 (s, 9 H), 6.82 (br s, 1 H), 8.01 (d, J=8.8 Hz, 1 H), 8.17 (m, 1 H), 8.46 (d, J=2.4 Hz, 1 H).

1. temperatureThe resulting mixture was then heated
2. temperatureat reflux for 5 hr
3. temperatureAfter cooling
4. extractionextracted with toluene
5. washThe extracts were washed with brine
6. dry with materialdried over Na2SO4
7. customevaporated
8. customThe residue was chromatographed on silica gel (50 ml) with toluene-EtOAc (5:1