Pyridine → tert-Butyl 3-iodo-1H-pyrrolo[2,3-b]pyridine-1-carboxylate

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Reaction Steps

1H-Pyrrolo[2,3-b]pyridine (2.00 g, 0.0169 mol; Aldrich) was dissolved in pyridine (17 mL, 0.21 mol; Acros) and cooled in an ice bath. A solution of 1.00 M of iodine monochloride in methylene chloride (18.6 mL; Aldrich) was added over 5 min. After 15 min the cooling bath was removed, and after another 30 min the solution was diluted with 200 mL of ethyl acetate. The organic solution was washed sequentially with 1 N hydrogen chloride and 1 N sodium hydroxide, dried over magnesium sulfate, and concentrated. The material was dissolved in 1,4-dioxane (85 mL, 1.1 mol; Acros) and treated with di-tert-butyldicarbonate (4.07 g, 0.0186 mol; Aldrich) and 4-dimethylaminopyridine (0.216 g, 0.00177 mol; Aldrich). The mixture was stirred at room temperature for 3 days. Excess di-tert-butyldicarbonate was destroyed by the addition of N,N-dimethyl-1,2-ethanediamine (1.7 mL, 0.015 mol). After stirring for 30 min, the solution was evaporated to dryness, taken up in ethyl acetate, then washed with dilute HCl and then saturated NaCl, dried over sodium sulfate, filtered and concentrated. Purification by silica gel chromatography produced the title compound in 2.03 g (35%) yield. MS m/z=345.01 (M+1). 1H NMR (400 MHz, CDCl3)™ ppm 8.527 (dd, J=4.8, 1.5 Hz, 1H) 7.796 (s, 1H) 7.717 (dd, J=7.9, 1.5 Hz, 1H) 7.276 (dd, J=7.9, 4.8 Hz, 1H) 1.671 (s, 9H). TLC Rf=0.50 in 3:1 hexanes/ethyl acetate.

Provenance & Evidence