[CH2:1](Cl)[O:2][CH3:3].[I:5][C:6]1[CH:11]=[C:10]([Si:12]([CH3:15])([CH3:14])[CH3:13])[N:9]=[C:8]([O:16][CH3:17])[C:7]=1[CH2:18][OH:19].C(N(C(C)C)C(C)C)C>C(Cl)Cl>[I:5][C:6]1[CH:11]=[C:10]([Si:12]([CH3:14])([CH3:13])[CH3:15])[N:9]=[C:8]([O:16][CH3:17])[C:7]=1[CH2:18][O:19][CH2:1][O:2][CH3:3]MOMCl (2.0 mL, 26.7 mmol) was added dropwise to a 0° C. solution of 2a (3 g, 8.9 mmol) and iPr2EtN (4.6 mL, 26.7 mmol) in dry CH2Cl2 (35 mL). The resulting mixture was allowed to warm to room temperature and stirred overnight. The reaction was quenched with 5% aq. NaHCO3 solution and the product was extracted with CH2Cl2. The combined organic phases were washed with brine, dried over MgSO4 and concentrated under reduced pressure to give 3.0 g (88% yield) of the crude product 3a as an orange oil. The crude product was sufficiently pure for the subsequent reaction. 1H NMR (300 MHz, CDCl3) δ0.27 (s, 9H), 3.46 (s, 3H), 3.98 (s, 3H), 4.71 (s, 2H), 4.75 (s, 2H), 7.51 (s, 1H); 13C NMR (75 MHz, CDCl3) δ−2.08, 53.79, 55.53, 67.85, 96.39, 113.84, 122.6, 132.98, 161.43, 166.37; IR (film, NaCl, cm−1) 2946, 1528, 1340, 1042, 840; LRMS (70 eV, EI) m/z (rel int %) 381 (M+), 366, 336, 320, 306, 169, 128, 84 (100), 73. HRMS m/z calcd for C12H20NO3SiI (M+) 381.0257, found 381.0241.
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