To a stirred solution of 2-[5-(toluene-4-sulfonyl)-1H-imidazol-4-yl]-pyridine (Tetrahedron Lett. 1976, 285) (1.65 g, 5.51 mmol) in dry DMF (15 mL) was added NaH (60% in mineral oil, 0.36 g, 9.0 mmol) at room temperature under N2. After 30 minutes stirring, SEM-Cl (1.21 mL, 6.83 mmol) was added through a syringe. The slurry was further stirred at room temperature for 6 hours, and then poured into cold H2O (100 mL), extracted with dichloromethane (3×50 mL). Combined dichloromethane solution was washed with H2O (2×50 mL) and brine (50 mL). Flash silica gel chromatography (hexane to 2:1 hexane/ethyl acetate) afforded the 2-[5-(Toluene-4-sulfonyl)-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazol-4-yl]-pyridin as a syrup intermediate in the forms of 1:1 regioisomers (1.89 g, 80%). 1H NMR δ −0.09 (s, 9H), 0.75 (t, 2H, J=7), 2.38 (s, 3H), 3.30 (t, 2H, J=7), 5.40 (s, 2H), 7.22 (d, 2H, J=8), 7.4 (t, 1H, J=6), 7.65–7.95 (m, 5 H), 8.70 (d, 1H, J=4) ppm; the other regio-isomer shows chemical shift at δ −0.02 (s, 9H), 0.8 (t, 2H, J=7), 2.41 (s, 3H), 3.41(t, 2H, J=7), 5.65 (s, 2H), 7.2–7.35 (m, 7.70–7.90 (m, 5H), 8.1 (d, 1H, J=8), 8.68 (d, 1H, J=4)ppm; (ESMS calcd for (C21H27N3O3SSI): 429.2; found: 430.4 (M+H)+.
