2,4-Dibromo-1-fluorobenzene → 3-(2,4-Dibromophenoxy)pyridin-2-amine

Participants

Reaction Steps

An nitrogen-purged 22 L 5-necked flask was charged with DMF (9 L) followed by slow addition of 2-aminopyridin-3-ol (250.0 g, 2270 mmol) and stirred with mechanical overhead agitator at ambient temperature for 30 minutes to dissolve material. 60% Sodium hydride (87.17 g, 2180 mmol) was added in portions with vigorous stirring and a nitrogen sweep of the reaction vessel. The pot temperature rose from 16° C. to 25° C. during the NaH addition. After the addition was complete, the reaction was stirred at ambient temperature for 60 minutes to ensure all NaH was consumed. 2,4-Dibromo-1-fluorobenzene (225.3 mL, 1816 mmol) was added and heated to 110° C. under nitrogen for 24 hours. The reaction was cooled to 60° C. and transferred to a 20 L flask and the majority of the DMF removed. The resultant sludge was diluted with 1N NaOH (8 L) and EtOAc (8 L) and the mixture was passed through a plug of celite and washed with EtOAc. The layers were separated and the aqueous was extracted with EtOAc (4 L). The combined organic layers were washed with 1 N NaOH (4 L) and 50% saturated brine (4 L), water (2 L) and concentrated until solids started to form. Hexanes (4 L) were added slowly and the mixture was concentrated to around 2 L volume. Hexanes (4 L) were added and the mixture was stirred for 1 hour to allow to cool to ambient temperature. The resulting slurry was filtered, dried on the filter and then dried under high vacuum overnight to afford 3-(2,4-dibromophenoxy)pyridin-2-amine (277.3 g, 44.4% yield).

Provenance & Evidence