1,3-Cyclohexanedione → 1-phenyl-1,2,9,10-tetrahydro[1,4]oxazino[2,3,4-jk]carbazol-7(8H)-one

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Reaction Conditions

Reaction Steps

To a mixture of 3-phenyl-2,3-dihydro-4H-1,4-benzoxazin-4-ylamine (1.042 g, 4.6 mmol) in toluene (30 mL) is added, with stirring, cyclohexane-1,3-dione (0.538 g, 4.8 mmol). The mixture is heated to 85° C. for 15 min, at which time p-toluenesulfonic acid monohydrate (0.874 g, 4.6 mmol) is added and the temperature increased to 110° C. The mixture is refluxed for 24 h, cooled to room temperature and concentrated. The residue is partitioned between CH2Cl2/1N NaOH and the organic layer is washed with brine and dried over magnesium sulfate. Column chromatography (100 g silica gel) using (acetone/hexane (25/75)) as eluent gave 0.475 g (34%) of 1-phenyl-1,2,9,10-tetrahydro[1,4]oxazino[2,3,4-jk]carbazol-7(8H)-one.

Provenance & Evidence