[CH3:1][O:2][C:3](=[O:16])[CH:4](P(OC)(OC)=O)[NH:5][C:6]([O:8][CH3:9])=[O:7].CC(C)=O.C(=O)=O.[O:24]1[CH2:29][CH2:28][CH:27]([CH:30]=O)[CH2:26][CH2:25]1>C1COCC1.CCOC(C)=O>[CH3:1][O:2][C:3](=[O:16])[C:4]([NH:5][C:6]([O:8][CH3:9])=[O:7])=[CH:30][CH:27]1[CH2:28][CH2:29][O:24][CH2:25][CH2:26]1To a solution of (Dimethoxy-phosphoryl)-methoxycarbonylamino-acetic acid methyl ester (0.34 g, 1.35 mmol) in THF (5.4 mL) at −78° C. (external, Acetone/CO2 bath) was added 1,1,3,3-tetramethguanidine (0.17 mL, 1.35 mmol). The solution was stirred for 15 min before Tetrahydro-pyran-4-carbaldehyde (0.15 g, 1.35 mmol) was added. The reaction was stirred at −78° C. for 2 h and then allowed to warm to room temperature. The reaction was diluted with EtOAc and washed with HCl (1N) and brine. The aqueous layers were back extracted with EtOAc. The combined organic layers were dried over Na2SO4 and concentrated. The crude oil was purified by column chromatography (SiO2, 20→100% EtOAc in Hexanes) to provide 2-Methoxycarbonylamino-3-(tetrahydro-pyran-4-yl)-acrylic acid methyl ester (0.15 g, 45%). LCMS-ESI+: calc'd for C11H17NO5: 243.11 (M+); Found: 243.96 (M+H+).
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