[OH:1][CH2:2][C:3]1[CH:4]=[CH:5][C:6]2[CH:10]=[C:9]([C:11]([OH:13])=O)[S:8][C:7]=2[CH:14]=1.C1CN([P+](Br)(N2[CH2:30][CH2:29][CH2:28]C2)N2CCCC2)CC1.F[P-](F)(F)(F)(F)F.C(O[CH2:44][CH2:45][O:46][NH2:47])C(C)C.CCN(C(C)C)C(C)C.CN([CH:60]=[O:61])C>O.CCOC(C)=O>[CH2:60]([O:61][CH:45]([O:46][NH:47][C:11]([C:9]1[S:8][C:7]2[CH:14]=[C:3]([CH2:2][OH:1])[CH:4]=[CH:5][C:6]=2[CH:10]=1)=[O:13])[CH3:44])[CH:29]([CH3:28])[CH3:30]To a solution of 6-hydroxymethyl-benzo[b]thiophene-2-carboxylic acid (1.76 g, 8.4 mmol, 1 eq) in DMF was added PyBrOP (4.3 g, 9.2 mmol), O-(isobutoxy-ethyl)-hydroxylamine (11.5 mL, 84.0 mmol) (prepared via procedure in WO0160785) and DIPEA (2.9 mL, 16.7 mmol). The reaction mixture was allowed to stir at r.t. for 2 h then diluted with water (40 mL) and EtOAc (40 mL). The organic layer was isolated, washed with brine (50 mL) and concentrated. The residue was purified by chromatography on silica gel eluting with EtOAc/heptane (1:1) to afford the title compound (1.8 g, 67% over 2 steps). LCMS m/z 322 [M+−H]+, 1H NMR (300 MHz, MeOD), δ: 0.83 (6H, d J=6.6 Hz, 2×CH3), 1.32 (3H, d J=5.9 Hz, CH3), 1.75 (1H, m, CH), 3.38 (2H, m, CH2), 4.63 (2H, s, CH2), 4.95 (1H, m, CH), 7.32 (1H, d J=8.2 Hz, ArH), 7.77 (3H, m, ArH).
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