[CH2:1]([O:3][O:4][P:5]([CH:11]([OH:20])[C:12]1[CH:19]=[CH:18][C:15]([CH:16]=O)=[CH:14][CH:13]=1)([O:7][O:8][CH2:9][CH3:10])=[O:6])[CH3:2].[N:21]([CH2:24][C:25]([O:27][CH2:28]C)=[O:26])=[N+:22]=[N-:23].CO.C[O-].[Na+]>C>[N:21]([C:24](=[CH:16][C:15]1[CH:18]=[CH:19][C:12]([CH:11]([P:5]([O:7][O:8][CH2:9][CH3:10])([O:4][O:3][CH2:1][CH3:2])=[O:6])[OH:20])=[CH:13][CH:14]=1)[C:25]([O:27][CH3:28])=[O:26])=[N+:22]=[N-:23]To a dry 1 L round bottom flask was added 10.9 g (40 mmol) of 37, 52 g (400 mmol, 10 equivalents) of ethyl α-azidoacetate and 200 mL of anhydrous MeOH and the solution stirred under argon at -78° C. To this was added via syringe over 10 minutes, 59 mL (320 mmol, 8 equivalents) of NaOMe, 5.4M in MeH. The reaction was stirred briefly (5 minutes) at -78° C., then at 0° C. (1 hour). The yellow suspension was partitioned between ice-cold brine (400 mL) and EtOAc (3×250 mL). The combined EtOAc was washed with brine (1×400 mL); dried well (MgSO4) and rotovapped (20° C.) to a light yellow solid. Trituration with ether:petroleum ether (35°-60° C.) provided 38 as a light yellow solid (7.72 g, 52%), mp 106°-110° C. 1H NMR (250 MHz, DMSO-d6) δ: 7.86 (d, 2H, J=8.2 Hz, aromatic) , 7.48 (dd, 2H, J=8.2, 1.8 Hz, aromatic), 6.95 (s, 1H, vinylic), 6.30 (dd, 1H, J=15.3, 5.5 Hz, OH), 5.01 (dd, 1H, J=14.3, 5.5 Hz, P--CH), 3.98 (m, 4H, OCH2), 3.87 (s, 3H, CO2CH3), 1.18 (t, 3, J=7.0 Hz, CH3), 1.16 (t, 3H, J=7.0 Hz, CH3); mp 106°-110° C. (dec).
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