This compound can be prepared in several ways: 1) By cyclization of 2-isopropylamino-4-methyl-4'-fluorobenzophenone (I) with potassium cyanate in hot acetic acid. 2) By cyclization of 2-isopropylamino-4-methyl-4'-fluorobenzophenone (I) with urea (A) or alkyl carbamates in the presence of an acid. 3) By condensation of 2-isopropylamino-4-methyl-4'-fluorobenzophenone (I) with ethyl chloroformate (B) at 100 C to give 2-(N ethoxycarbonyl-N-isopropylamino)-4-methyl-4'-fluorobenzophenone (II), followed by cyclization with ammonium acetate at 130 C.