Tert-butyl6-amino-2-chloro-4-methylnicotinate → tert-Butyl 2-(3-bromophenyl)-5-chloro-7-methylimidazo[1,2-a]pyridine-6-carboxylate

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Reaction Conditions

Reaction Steps

A flask charged with chlorobenzene (300 ml) was heated to reflux (140° C. oil bath) and to this was added sequentially 1-bromo-3-(2-bromo-1,1-dimethoxyethyl)benzene (56.05 g, 173 mmol) as an oil, and tert-butyl 6-amino-2-chloro-4-methylnicotinate (33.91 g, 140 mmol) as a powder, rinsing both with additional chlorobenzene (70 mL total) to facilitate transfer. The reaction was returned to reflux and heated for 90 min, then cooled and poured slowly into vigorously stirred Et2O (1500 mL). The resulting suspension was stirred for 15 min, then solids were collected by vacuum filtration to afford the product (47 g, 111 mmol, 64.4% yield) as a tan powdery solid. A 3 g sample of product was first purified by biotage (80 g SiO2, 0% (3 CV), 0-60% (15 CV), 60% (2 CV), EtOAc in hexanes), then recrystallized from hot acetonitrile to afford a high purity sample for spectra. 1H NMR (500 MHz, CDCl3) δ 8.14 (t, J=1.7 Hz, 1H), 8.02 (d, J=0.5 Hz, 1H), 7.89 (dq, J=7.7, 0.9 Hz, 1H), 7.48 (ddd, J=8.0, 2.0, 1.1 Hz, 1H), 7.41-7.39 (m, 1H), 7.32 (t, J=7.9 Hz, 1H), 2.45 (d, J=0.9 Hz, 3H), 1.65 (s, 9H). 13C NMR (126 MHz, CDCl3) δ 164.3, 145.6, 145.2, 135.3, 133.6, 131.3, 130.3, 129.2, 124.7, 123.9, 123.0, 121.7, 115.4, 107.6, 83.9, 28.1, 19.9. LCMS (M+H)=421.3.

Provenance & Evidence