反应详情

A solution of N-(t-butyldimethylsilyl)-4-(2-acetoxyethyl)-azetidin-2-one (41.7 g, 0.154 mol) in anhydrous methanol (415 ml) is stirred under a N2 atmosphere with ice-bath cooling. A solution of sodium methoxide (415 mg, 7.7 mmol) in anhydrous methanol (15 ml) is added and the resulting solution is stirred in the cold for 2 more hrs. Acetic acid (2.2 ml) is then added and the solvents are evaporated in vacuo (i.v.). The residue is taken up in EtOAc (300 ml), washed with H2O (4×75 ml), 5% NaHCO3 (75 ml) and brine, dried with MgSO4 and evaporated i.v. to a clear oil (21.3 g). This material is purified by chromatography on a Baker silica gel column (425 g, packed under EtOAc). After a 100 ml forefraction, 25 ml EtOAc fractions are collected every 2.5 mins. Fractions 41-49 yield starting material and fractions 51-90 afford N-(t-butyldimethylsilyl)-4-(2-hydroxyethyl)-azetidin- 2-one (19.4 g) as a clear oil: ir (neat) 2.88, 5.73, 5.80, 7.52, 7.67, 7.99, 8.40, 11.95, and 12.18 cm-1 ; nmr (CDCl3)δ 0.25 (s, 6), 0.98 (s, 9), 1.82 (m, 2), 2.67 (dd, 1), 3.17 (dd, 1), 3.67 (t, 2), and 3.67 (m,1); mass spectrum m/e 172.

1. temperaturecooling
2. customthe solvents are evaporated in vacuo (i.v.)
3. washwashed with H2O (4×75 ml), 5% NaHCO3 (75 ml) and brine
4. dry with materialdried with MgSO4
5. customevaporated i.v
6. customThis material is purified by chromatography on a Baker silica gel column (425 g, packed under EtOAc)
7. customAfter a 100 ml forefraction, 25 ml EtOAc fractions are collected every 2.5 mins
8. customFractions 41-49 yield