Trifluoroacetic acid → 4-Nitroso-3-phenyl-3,4-dihydro-2H-1,4-benzoxazine

Participants

Reaction Steps

To a mixture of 3-phenyl-3,4-dihydro-2H-1,4-benzoxazine (17 g, 80.5 mmol) in ethyl ether (100 mL) is added trifluoroacetic acid (6.2 mL 80.5 mmol). The resulting solution is chilled to 5° C. in an ice bath, to which n-butyl nitrite (9.4 mL 80.5 mmol) is added dropwise. The mixture is stirred for 1 h and transferred to a separatory funnel to which is slowly added potassium carbonate (2.6 g, 18.8 mmol) in water (200 mL). Solids formed in the ether layer. The layers are separated and ethyl ether (100 mL) is added to dissolve the solids. The ether layer is washed twice with water (200 mL), dried over magnesium sulfate, filtered and concentrated. The resulting oil is chilled in the refrigerator overnight. The solids formed from the oil are ground-up in hexanes and collected by filtration to give 15.7 g (81%) of 4-nitroso-3-phenyl-3,4-dihydro-2H-1,4-benzoxazine.

Provenance & Evidence