Imidazole → Tert-butyl(dimethyl)silyl 2-(iodomethyl)-2-propenyl ether

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A solution of iodine (1.49 g, 5.85 mmol) in anhydrous CH2Cl2 (3×10 mL, then 4×1 mL to rinse) was added dropwise to a stirred mixture of imidazole (0.441 g, 6.48 mmol) and triphenylphosphine (1.50 g, 5.71 mmol) in anhydrous CH2Cl2 (3 mL) at 0° C. under N2. After stirring at 0° C. for 30 min, a solution of 2-({[tert-butyl(dimethyl)silyl]oxy}methyl)-2-propen-1-ol (164) (reported by Chen et al., US 2007213341 A1, by monosilylation of 2-methylene-1,3-propanediol) (1.00 g, 4.94 mmol) in anhydrous CH2Cl2 (4 mL, then 4×1 mL to rinse) was added, and the mixture was stirred at 0-8° C. for 5 h. The resulting mixture was concentrated carefully under reduced pressure, and the residual oil was chromatographed on silica gel. Elution with pentane firstly gave foreruns, and then further elution with 10% CH2Cl2/pentane gave tert-butyl(dimethyl)silyl 2-(iodomethyl)-2-propenyl ether (165) (1.46 g, 95%) as a volatile pink oil that was used directly in the next step; 1H NMR (CDCl3) δ 5.31 (br s, 1H), 5.19 (d, J=1.3 Hz, H), 4.31 (s, 2H), 3.95 (s, 2H), 0.92 (s, 9H), 0.10 (s, 6H).

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