反应详情

Anhydrous chromium trioxide (CrO3) (1.94 g, 19.4 mmol) is added to a solution of anhydrous pyridine (3.07 g, 38.8 mmole) in anhydrous methylene chloride (CH2Cl2) (50 ml). The resulting mixture is stirred at room temperature for 15 mins. A solution of N-(t-butyldimethylsilyl)-4-(2-hydroxyethyl)-azetidin-2-one (0.74 g, 3.23 mmol) in anhydrous CH2Cl2 (5 ml) is added all at once. After stirring at room temperature for 5 mins, the mixture is decanted and the dark, gummy residue is washed with more CH2Cl2. The combined CH2Cl2 supernatant is evaporated i.v. The residue is tabken up in diethyl ether and filtered to remove chromium salts. The ethereal filtrate is washed with 5% NaHCO3, 5% HCl, 5% NaHCO3 and brine, dried with MgSO4, filtered, and evaporated i.v. to yield N-(t-butyldimethylsilyl)-4-(2-oxoethyl)-azetidin-2-one (0.54 g) as an off-white solid: ir (CHCl3) 5.77, 5.80, 7.36, 7.60, 7.99, 8.50 and 11.95 cm-1 ; nmr (CDCl3) δ 0.23 (s, 3), 0.27 (s, 3), 0.98 (s, 9), 2.63 (ddd, 1), 2.65 (dd, 1), 3.07 (ddd, 1), 3.37 (dd), 3.97 (m, 1), and 9.78 (t, 1); mass spectrum m/e 170 and 128.

1. stirringAfter stirring at room temperature for 5 mins
2. customthe mixture is decanted
3. washthe dark, gummy residue is washed with more CH2Cl2
4. customThe combined CH2Cl2 supernatant is evaporated i.v
5. filtrationfiltered
6. customto remove chromium salts
7. washThe ethereal filtrate is washed with 5% NaHCO3, 5% HCl, 5% NaHCO3 and brine
8. dry with materialdried with MgSO4
9. filtrationfiltered
10. customevaporated i.v