Phosphorus oxychloride → Ethyl 4-chloro-7-methyl-1,8-naphthyridine-3-carboxylate
Reaction equation
O[C:2]1[C:11]2[C:6](=[N:7][C:8]([CH3:12])=[CH:9][CH:10]=2)[N:5]=[CH:4][C:3]=1[C:13]([O:15][CH2:16][CH3:17])=[O:14].P(Cl)(Cl)([Cl:20])=O>>[Cl:20][C:2]1[C:11]2[C:6](=[N:7][C:8]([CH3:12])=[CH:9][CH:10]=2)[N:5]=[CH:4][C:3]=1[C:13]([O:15][CH2:16][CH3:17])=[O:14]Participants
Conditions
- Temperature
- 60 °C
Procedure
A mixture of 10 g of ethyl 4-hydroxy-7-methyl-1,8-naphthyridine-3-carboxylate and 50 ml of phosphorus oxychloride was heated at 60°C with stirring for 1 hour. The excess phosphorus oxychloride was removed under reduced pressure and the product was poured into ice-water. The insoluble matter was filtered off, the filtrate was adjusted to pH 8 by the addition of aqueous ammonia under cooling and extracted with ether. The extracts were dried over anhydrous magnesium sulfate. Then 0.5 g of activated carbon was added to the ether extracts for decoloration. The ether extracts were filtered, concentrated to a small volume and cooled. The precipitate was filtered to provide 8.6 g of ethyl 4-chloro-7-methyl-1,8-naphthyridine-3-carboxylate as yellow needles, m.p. 99°-100°C (decomp.).
Workup
- customThe excess phosphorus oxychloride was removed under reduced pressure
- additionthe product was poured into ice-water
- filtrationThe insoluble matter was filtered off
- additionthe filtrate was adjusted to pH 8 by the addition of aqueous ammonia
- temperatureunder cooling
- extractionextracted with ether
- dry with materialThe extracts were dried over anhydrous magnesium sulfate
- additionThen 0.5 g of activated carbon was added to the ether
- filtrationThe ether extracts were filtered
- concentrationconcentrated to a small volume
- temperaturecooled
- filtrationThe precipitate was filtered
Sources & evidence
- ORD record
- ord-45347fd2c5154bbfaa72e68b8353e7a6
- Source dataset
- uspto-grants-1976_06
- Patent number
- US03963736
Reaction notes
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