Acetic acid, 2-(triphenylphosphoranylidene)-, methyl ester → tert-Butyl 3-(2-methoxy-2-oxoethylidene)azetidine-1-carboxylate
Reaction equation
[C:1]([O:5][C:6]([N:8]1[CH2:11][C:10](=O)[CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].[CH3:13][O:14][C:15]([CH:17]=P(C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)=[O:16]>C1(C)C=CC=CC=1>[C:1]([O:5][C:6]([N:8]1[CH2:11][C:10](=[CH:17][C:15]([O:14][CH3:13])=[O:16])[CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2]Participants
4
Procedure
3-Oxo-azetidine-1-carboxylic acid tert-butyl ester (1.67 g; 9.7 mmol) and methoxycarbonyl-methylene-triphenylphosphorane (3.42 g; 10.25 mmol) are dissolved in toluene (5 ml), refluxed for 2.5 hours and left over night at room temperature. The precipitate is filtered off, washed with TBME, and the filtrate purified via chromatography (TBME/hexane 2:8>3:7) to yield the title compound as colorless crystals. 1H-NMR (400 MHz; DMSO-d6): 5.90 (m, 1H); 4.71 (bs, 2H); 4.58 (bs, 2H); 3.67 (s, 3H); 1.42 (s, 9H). MS (m/z) ES+: 171 (10; MH+ minus tert-butyl); 57 (100).