反应详情

Freshly recrystallized p-carboxy benzene sulfonylazide (241 mg, 1.06 mmol) is added to a solution of 4-(3-benzyloxycarbonyl-2-oxopropyl)-azetidin-2-one (276 mg, 1.06 mmol) in anhydrous acetonitrile (6.6 ml). The resulting suspension is cooled in an ice-bath and stirred while Et3N (443 μl, 3.18 mmol) is added. The resulting yellow solution is stirred at room temperature. A precipitate forms quickly. After 90 mins, the mixture is diluted with EtOAc (50 ml) and filtered. The filtrate is washed with H2O (2×10 ml), 0.5N NaOH (2×10 ml), H2O (4×10 ml) and brine, dried with MgSO4, filtered, and evaporated i.v. to an off-white solid (273 mg). This is triturated with Et2O to provide 4-(3-benzyloxycarbonyl-3-diazo-2-oxopropyl)-azetidin-2-one (227 mg) as a cream colored powder: ir (film from CHCl3) 3.0, 4.65, 5.66, 5.82, 6.05, 7.21, 7.70 and 8.23 cm-1 ; nmr (CDCl3) δ2.63 (ddd, 1), 2.97 (dd, 1), 3.15 (ddd, 1), 3.40 (dd, 1), 3.98 (m, 1), 5.27 (s, 2), 6.13 (m, 1), and 7.38 (s, 5); mass spectrum m/e 259, 245, 231, and 218.

1. temperatureThe resulting suspension is cooled in an ice-bath
2. additionis added
3. filtrationfiltered
4. washThe filtrate is washed with H2O (2×10 ml), 0.5N NaOH (2×10 ml), H2O (4×10 ml) and brine
5. dry with materialdried with MgSO4
6. filtrationfiltered
7. customevaporated i.v
8. customThis is triturated with Et2O