I(O)(=O)(=O)=[O:2].[CH2:6]([O:9][N:10]1[C:16](=[O:17])[N:15]2[CH2:18][C@H:11]1[C:12]([CH3:21])=[CH:13][C@H:14]2[CH2:19][OH:20])[CH:7]=[CH2:8]>C(#N)C.[O-2].[Cr+6].[O-2].[O-2]>[CH2:6]([O:9][N:10]1[C:16](=[O:17])[N:15]2[CH2:18][C@H:11]1[C:12]([CH3:21])=[CH:13][C@H:14]2[C:19]([OH:2])=[O:20])[CH:7]=[CH2:8]To a solution of periodic acid (2 g, 10.42 mmol) in wet acetonitrile (20 mL) (0.75% water by volume) at room temperature was added chromium(VI) oxide (4 mg, 0.04 mmol). The mixture was stirred until complete dissolution was achieved. This solution (5.47 mL, 3 eq) was added dropwise at 0° C. to a solution of (2S,5R)-6-(allyloxy)-2-(hydroxymethyl)-4-methyl-1,6-diazabicyclo[3.2.1]oct-3-en-7-one (Intermediate 14, 0.212 g, 0.95 mmol) in wet acetonitrile (10 mL) (0.75% by volume). The reaction mixture went from clear orange to cloudy brownish color to cloudy green suspension. After 30 minutes, LC/MS showed desired product mass and some remaining starting material. Another equivalent of the oxidizing agent solution (1.82 mL) was added. After 30 minutes, the reaction mixture was diluted with ethyl acetate and washed with 1 to 1 brine/water. The organics were dried over magnesium sulfate, filtered and concentrated to afford a green foam (0.193 g, 86%).
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