Anisole → 4-Bromo-6-(5-chloropyridin-2-yl)-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine

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Reaction Steps

Phosphorus oxybromide (14 g, 49 mmol) was added portionwise over 2 min to a stirred suspension of 6-(5-chloropyridin-2-yl)-4-methoxy-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine (3.36 g, 12.1 mmol), anisole (50 mL), and acetonitrile (50 mL) in a 250 mL flask. The stirred mixture clarified briefly and was then heated at reflux. The mixture was removed from the heat after 4.5 h. The cooled mixture was diluted with CH2Cl2 (100 mL), and poured onto a mixture of crushed ice (250 g) and 50% aqueous KOH (20 mL; 0.18 mol). The pH of the mixture was then adjusted to 12 with 2M aq. KOH, and extracted with CH2Cl2 (300 mL). The aqueous phase was diluted with brine (200 mL) and extracted with CH2Cl2 (2×100 mL). The combined CH2Cl2 layers were washed with saturated NaHCO3 (200 mL), dried (Na2SO4), filtered and concentrated to a brown oil which was purified by silica gel column (0-50% ethyl acetate/hexane) to give a yellow solid (1.48 g).

Provenance & Evidence