To a stirred partial solution of 2-aminooxazole(169 mg, 2.0 mmol) in dry THF (10 ml), cooled to −78° C., under argon, was added slowly n-BuLi(1.33M, 1.5 ml, 2.0 mmol), followed after 1 h by 5(R)-methylsulfonyloxymethyl-3-(3-fluoro-4-(3,6-dihydro-(2H)-pyran-4-yl)phenyl)oxazolidin-2-one (see Example 41; 371 mg, 1.0 mol) suspended in dry THF(20 ml). The reaction was allowed to come to room temperature and then refluxed for 24 h. The reaction was quenched with ammonium chloride solution(10%w/v, 30 ml), extracting the mixture with chloroform (3×50 ml). The extracts were dried (magnesium sulfate), concentrated by rotary evaporation chromatographed by MPLC (Merck 9385 silica, 3-10% gradient methanol/dichloromethane eluent) and the pure fractions combined, concentrated and triturated with diethyl ether to. give the title compound (25 mg, 4.6%). NMR (300 Mz, DMSO-d6), δ/ppm: 2.31 (m, 2H), 3.35 (m, 2H, obscured), 3.64 (dd, 1H), 3.84 (t, 2H), 3.90 (m, 1H), 4.15 (m, 1H), 4.24 (m, 2H), 4.46 (m, 1H), 5.97 (m, 1H), 6.90 (m, 1H), 7.19 (m, 2H, partially obscured), 7.37 (dd, 1H), 7.44 (dd, 1H). MS: ES+ (M+H)=360.
