Reaction #4373

Reaction equation

sodium hydroxide

sodium hydroxide

3-methoxy-2-methylpyridine 1-oxide

chloroform

phosphorus trichloride

chloroform

→

3-methoxy-2-methylpyridine

Solvents

water

Conditions

Workup

1. 1
   TemperatureThe temperature was maintained at <10° C. during the addition
2. 2
   workup.ADDITIONafter the addition
3. 3
   Temperaturewas then heated
4. 4
   Temperatureunder reflux for an hour
5. 5
   OtherThe organic phase was separated
6. 6
   Extractionthe aqueous phase was extracted three times with 50 ml portions of chloroform
7. 7
   DryingThe combined organic phase and extracts were dried over anhydrous sodium suflate
8. 8
   Filtrationfiltered
9. 9
   Otherevaporated under reduced pressure

Procedure

Under a nitrogen atmosphere, a magnetically stirred solution of 25.8 g (0.185 mole) of 3-methoxy-2-methylpyridine 1-oxide and 200 ml of chloroform cooled to 0° C. was treated dropwise a solution of 75.6 g (0.556 mole) of phosphorus trichloride and 50 ml of chloroform. The temperature was maintained at <10° C. during the addition. The solution was stirred for 20 minutes after the addition was complete, was allowed to warm to room temperature, and was then heated under reflux for an hour. When again at room temperature, the solution was poured into a mixture of ice and water, and the mixture was then adjusted to pH 13 by the addition of 5N sodium hydroxide and solid sodium hydroxide while keeping the mixture cold. The organic phase was separated and the aqueous phase was extracted three times with 50 ml portions of chloroform. The combined organic phase and extracts were dried over anhydrous sodium suflate, filtered, and evaporated under reduced pressure to give 3-methoxy-2-methylpyridine as an oil: b.p. 46° C. at 1.8 mmHg; yield 21.5 g (94%). Lit. b.p. 84.5°-85.5° C. at 17 mmHg [A. L. Logothetis, J. Org. Chem., 29, 1834-1837 (1969)].

Source