Phosphorus oxychloride → HCID 20382070, compound

Participants

Reaction Steps

A solution of 25 g of 3-(o-fluorophenoxy)pyridine N-oxide in 50 ml of chloroform is added dropwise to 77 g of refluxing phosphorous oxychloride. The mixture is refluxed for 2 hours. The mixture is concentrated at reduced pressure. The oil is dissolved in 500 ml dichloromethane, washed with 50 ml of ice cold concentrated ammonium hydroxide and dried over anhydrous MgSO4. The organic phase is separated, concentrated at reduced pressure and distilled to yield the mixture of desired chlorinated pyridines as an oil, bp 92°-105° C. at 0.1 mm. The oil is dissolved in 50 ml of toluene and chromatographed over 450 g of silica gel in toluene to yield in the first eluate 6-chloro-3-(o-fluorophenoxy)pyridine. Continued elution with toluene yields 2-chloro-3-(o-fluorophenoxy)pyridine. Finally elution with toluene-methanol (50:50) yields 4-chloro-3-(o-fluorophenoxy)pyridine.

Provenance & Evidence