Reaction equation
C([Li])CCC.C(NC(C)C)(C)C.[C:13]([O:16][CH2:17][C:18]1[CH:23]=[CH:22][CH:21]=[CH:20][CH:19]=1)(=[O:15])[CH3:14].[Si:24]([N:31]1[C@H:34]([CH2:35][CH:36]=[O:37])[C@@H:33]([C@H:38]([O:40][Si:41]([C:44]([CH3:47])([CH3:46])[CH3:45])([CH3:43])[CH3:42])[CH3:39])[C:32]1=[O:48])([C:27]([CH3:30])([CH3:29])[CH3:28])([CH3:26])[CH3:25]>O1CCCC1>[Si:24]([N:31]1[C@H:34]([CH2:35][CH:36]([OH:37])[CH2:14][C:13]([O:16][CH2:17][C:18]2[CH:23]=[CH:22][CH:21]=[CH:20][CH:19]=2)=[O:15])[C@@H:33]([C@H:38]([O:40][Si:41]([C:44]([CH3:47])([CH3:46])[CH3:45])([CH3:42])[CH3:43])[CH3:39])[C:32]1=[O:48])([C:27]([CH3:30])([CH3:28])[CH3:29])([CH3:26])[CH3:25]Participants
Reactant 4
Product 1
Reagents, catalysts & solvents 1
Conditions
- Temperature
- -78 °C
Procedure
n-Butyllithium (1.81 mmol) is added by syringe to a solution of diisopropylamine (1.81 mmol) in 9 ml of freshly distilled tetrahydrofuran at -78° C. The resulting solution is stirred for 15 min at -78° C. Benzyl acetate (1.81 mmol) is then added dropwise by syringe and the resulting solution is stirred at -78° C. for 20 min. A solution of (3S,4R)-1-(t-butyldimethylsilyl)-3-[(R)-1-(t-butyldimethylsilyloxy)ethyl]-4-(2-oxoethyl)azetidin-2-one (1.64 mmol) in 3 ml of anhydrous tetrahydrofuran is added slowly by syringe. The reaction mixture is stirred at -78° C. an additional 15 min and then quenched by addition of saturated aqueous ammonium chloride solution. Ethyl acetate (50 ml) is added and the organic phase is separated, washed with water (2×10 ml) and brine and dried over magnesium sulfate. Removal of solvents in vacuo gives a white solid which is chromatographed on a short silica gel column (40% ether in petroleum ether) to yield (3S,4R)-1-(t-butyldimethylsilyl)-3-[(R)-1-(t-butyldimethylsilyloxy)ethyl]-4-(3-benzyloxycarbonyl-2-hydroxypropyl)azetidin-2-one. n.m.r. (CDCl3) δ7.32(s,5), δ5,1(s,2), δ4.0(m,3), δ2,4-3,8(m,4), δ2.0(m,2), δ1.25(overlapping d, 3), δ0.95(s,9), δ0.9(s,9), δ0.3(s,6), δ0.18(s,6).
Workup
- stirringthe resulting solution is stirred at -78° C. for 20 min
- stirringThe reaction mixture is stirred at -78° C. an additional 15 min
- customquenched by addition of saturated aqueous ammonium chloride solution
- additionEthyl acetate (50 ml) is added
- customthe organic phase is separated
- washwashed with water (2×10 ml) and brine
- dry with materialdried over magnesium sulfate
- customRemoval of solvents in vacuo
- customgives a white solid which
- customis chromatographed on a short silica gel column (40% ether in petroleum ether)
Sources & evidence
- ORD record
- ord-befecda3a2834194a0fcbce2f30a8afe
- Source dataset
- uspto-grants-1986_09
- Patent number
- US04610820
Linked notes
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