Manganese dioxide (0.041 g, 0.470 mmol) was added to a solution of ({[4-(2′-hydroxymethyl-6′-methyl-biphenyl-3-sulfonyl)-5-methylsulfanyl-thiophen-2-yl]-imino-methyl}-carbamic acid tert-butyl ester (0.025 g, 0.047 mmol) [example 213, step b] in dichloromethane [5 mL] and refluxed for 3 hours. The reaction was filtered through Celite and evaporated. The crude residue was dissolved in anhydrous THF [2 mL] and added to a solution of (diethoxy-phosphorylmethyl)-phosphonic acid diethyl ester (0.011 g, 0.061 mmol) and sodium hydride (0.003 g, 0.056 mmol) in THF [2 mL] at room temperature and stirred for 0.5 hours. A solution of 1N NaOH/MeOH (1/1) [10 mL] was added and the crude product was extracted with ether, dried with magnesium sulfate and evaporated. Column chromatography (50% EtOAc in hexanes) of the residue yielded the title compound (0.019 g, 57%) as a solid. ESI-MS (m/z): Calcd. for C30H37N2O7PS3: 664.15; found: 664.8.
