2-Aminopyridine → Tert-butyl 4-(imidazo[1,2-a]pyridin-3-yl)piperidine-1-carboxylate

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Reaction Steps

To a solution of 1.15 g of 1-tert-butoxycarbonyl-4-(1-bromo-formylmethyl)piperidine (from Step C) in 15 mL ethanol was added 388 mg of 2-aminopyridine. After refluxing for 18 h, the solvent was evaporated. The mixture was partitioned between ethyl acetate and saturated sodium bicarbonate solution. Aqueous layer was extracted with ethyl acetate (3×). The combined organic phase was washed with brine, dried over magnesium sulfate and concentrated. The residue was purified by flash chromatography with 50% ethyl acetate in hexanes, followed by 100% ethyl acetate to give the title compound as a solid. 1H NMR (500 MHz, CDCl3) δ 1.48 (s, 9H), 1.70 (m, 2H), 2.06 (d, J=13 Hz, 2H), 2.93–3.02 (m, 3H), 4.26 (br, 2H), 6.87 (t, J=6.8 Hz, 1H). 7.21(m, 1H), 7.44(s, 1H), 7.69(d, J=9.2 Hz,1H), 7.99 (d, J=6.9 Hz, 1H).

Provenance & Evidence