1,3-Cyclohexanedione → 5-methyl-1-phenyl-1,2,9,10-tetrahydro[1,4]oxazino[2,3,4-jk]carbazol-7(8H)-one

Participants

Reaction Conditions

Reaction Steps

To a mixture of 7-methyl-3-phenyl-2,3-dihydro-4H-1,4-benzoxazin-4-amine (5.95 g, 24.8 mmol) in toluene (175 mL) is added while stirring 1,3 cyclohexandione (2.86 g, 25.5 mmol). The mixture is heated to 95° C. for 20 min, at which time p-toluenesulfonic acid monohydrate (4.71 g, 24.8 mmol) is added and the temperature is increased to 106° C. for 1 h. The mixture is refluxed for 12 h, then cooled to room temperature and concentrated. The residue is partitioned between CH2Cl2/1N NaOH. The organic layer is washed with brine, dried over magnesium sulfate and concentrated to dryness. Column chromatography (100 g silica gel) using acetone/hexane (25/75) as eluent gave 4.06 g (51%) of 5-methyl-1-phenyl-1,2,9,10-tetrahydro[1,4]oxazino[2,3,4-jk]carbazol-7(8H)-one; mp 171° C.

Provenance & Evidence