Sodium Hydroxide → 8-Chloro-3-fluoro-1,5-naphthyridine

Temperature

110 °C

5-((5-fluoropyridin-3-ylamino)methylene)-2,2-dimethyl-1,3-dioxane-4,6-dione. A 150 mL sealed tube was charged with 2,2-dimethyl-1,3-dioxane-4,6-dione (6.0 g, 41.6 mmol) and trimethyl orthoformate (41.6 mL, 41.6 mmol). This was heated to 100° C., and stirred at this temperature for 2 hours. Reaction then cooled to 30° C. and 5-fluoropyridin-3-amine (4.7 g, 41.6 mmol) added portion-wise. Reaction vessel resealed and mixture stirred at 100° C. for 3 hours. LC/MS shows completion. Reaction mixture was cooled to room temperature, diluted with hexane, filtered, and air dried to yield 5-((5-fluoropyridin-3-ylamino)methylene)-2,2-dimethyl-1,3-dioxane-4,6-dione (9.1 g, 82% yield) as a bright yellow solid. MS [M+H]=267.2. Calc'd for Cl2H11FN2O4=266.2. 2) 7-fluoro-1,5-naphthyridin-4(1H)-one. A 500 mL round bottom flask equipped with a reflux condenser was charged with 5-((5-fluoropyridin-3-ylamino)methylene)-2,2-dimethyl-1,3-dioxane-4,6-dione (8.0 g, 30.0 mmol) and diphenyl ether (83.5 mL). This was heated to 250° C. in heating mantle and allowed to stay at this temperature for five minutes. Cooled to room temperature, diluted with hot hexanes, and filtered to afford 7-fluoro-1,5-naphthyridin-4(1H)-one (2.2 g, 45% yield) as a crude brown solid. The title compound was used without further purification. MS [M+H]=165.2, Calc'd for C8H5FN2O=164.14. 3) 8-chloro-3-fluoro-1,5-naphthyridine. A pressure resistant vial was charged with 7-fluoro-1,5-naphthyridin-4(1H)-one (600 mg, 3.66 mmol) and POCl3 (6.8 mL, 73.1 mmol). Vessel sealed and stirred at 110° C. for 16 hrs. Reaction mixture was cooled to room temperature and poured onto ice while stirring vigorously. While keeping reaction mixture at 0° C., it was basified to pH˜8 with 6N NaOH. Product extracted with dichloromethane. Organic layer collected, dried over sodium sulfate and concentrated to afford desired material. This was passed through a silica plug in 1-5% (90:10:1 DCM/MeOH/NH4OH)/DCM to afford 8-chloro-3-fluoro-1,5-naphthyridine (430 mg, 64% yield) as a tan solid. MS [M+H]=182.9. Calc'd for C8H4ClFN2=182.58

1. customThe title compound was used without further purification
2. customVessel sealed
3. customReaction mixture
4. temperaturewas cooled to room temperature
5. additionpoured onto ice
6. stirringwhile stirring vigorously
7. customreaction mixture at 0° C.
8. extractionProduct extracted with dichloromethane
9. customOrganic layer collected
10. dry with materialdried over sodium sulfate
11. concentrationconcentrated
12. customto afford desired material

ORD record

ord-a85cad7d123d4a2d91ac280701aee057

Source dataset

uspto-grants-2012_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08198448B2