2-Aminopyridine → Ethyl imidazo[1,2-a]pyridine-2-carboxylate

Participants

Reaction Steps

3 g (31.9 mmol) of 2-aminopyridine were dissolved in 65 ml of tetrahydrofurane with magnetic stirring. The addition of 4.44 ml (31.9 mmol) of ethyl bromopyruvate caused precipitation of a solid. The heterogenous mixture was stirred with reflux for 4 h. After returning to r.t., the solid was isolated by filtration and taken up in 65 ml of ethanol in order to be stirred with reflux in 65 ml of ethanol for 16 h. After returning to r.t., the solid was isolated by filtration. The filtrate was placed in ice in order to facilitate crystallization of the product which was collected by filtration and thus so forth until the liquid phase remained limpid. The solid was rinsed with 30 ml of diisopropyl ether and dried in a vacuum bell jar in order to obtain 5.14 g (yield=84%) of ethyl imidazo[1,2-a]pyridine-2-carboxylate as a white powder. LC-MS: m/z=191 (MH+); UV purity at 254 nm=99%. 1H NMR (300 MHz, DMSO) δ 8.95 (s, 1H), 8.84 (d, J=6.8 Hz, 1H), 7.98-7.80 (m, 2H), 7.46 (t, J=7.2 Hz, 1H), 4.43 (q, J=7.1 Hz, 2H), 1.35 (d, J=7.1 Hz, 3H).

Provenance & Evidence