[C:1]([O:4][CH:5]=[CH:6][CH:7]1[NH:10][C:9](=[O:11])[CH2:8]1)(=[O:3])[CH3:2].[H][H]>C(OCC)(=O)C.[Pd]>[C:1]([O:4][CH2:5][CH2:6][CH:7]1[NH:10][C:9](=[O:11])[CH2:8]1)(=[O:3])[CH3:2]A solution of 4-(2-acetoxyvinyl)-2-azetidinone (10.0 g, 0.065 mole) in 200 ml ethyl acetate containing 100 mg of 10% Pd/C is hydrogenated on a Parr shaker at 25° C. under 40 psi hydrogen for 15 minutes. The mixture is filtered through a bed of Supercel and washed with additional ethyl acetate. The combined filtrate is evaporated in vacuo to give 4-(2-acetoxyethyl)-2-azetidinone (10.0 g) as a crystalline solid. Recrystallization from ether affords white crystals: M.P. 44°-7°; ir (CHCl3)μ 5.66, 5.74; nmr (CDCl3) τ3.44 (broad s, 1, NH), 5.82 (m, 2, CH2OCOCH3), 6.29 (m, 1, C--4H), 6.87 (1/2 AB pattern further split in four by C--4H and NH, 1, Jgem =12.8 Hz, J=4.5H JNH =1.9 Hz, 7.38 (1/2 AB pattern further split in four by C--4H and NH, 1, Jgem =12.8 Hz, J=2.3 Hz, JNH =1.0 Hz), 7.93 and 8.02 (s on m, total 5, OCOCH3 and CH2CH2OCOCH3, respectively).
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