To 200 ml of t-amyl alcohol were poured 12.9 g of 97% oxindole, 20.0 g of 4,4'-diaminobenzophenone, and 26.43 g of potassium-t-butoxide. By use of a Molecular Sieves 4A tower which served as a dehydrator, the resultant mixture was refluxed with heat for 12 hours. Thereafter, the reaction mixture was cooled. An aqueous solution prepared by diluting 25 g of 35% HCl with 200 g water was added. The resultant mixture was stirred for 1.5 hours while being cooled with ice, and yellow crystals that precipitated were collected by filtration. The resultant crude product was washed with acetone, to thereby obtain 4.6 g (yield 15%) of the title compound in the form of yellow crystals. The melting point and elementary analysis data are shown in Table 15, and NMR and MS spectrum data are shown in Table 16.
