Synthesis of some new pyrazoloquinazolinone and quinazolinone derivatives

The benzoxazinone derivative 2‐(6,8‐dibromo‐4‐oxo‐4 H ‐benzo[ d ]‐1,3‐oxazin‐2‐yl)‐3‐(4‐methoxyphenyl) acrylonitrile ( 1 ) has been used as a starting material for preparation of the hitherto unknown pyrazoloquinazolinone and quinazolinone derivatives. Under different conditions the benzoxazinone ( 1 ) was reacted with hydrazine hydrate to provide the pyrazolocarbonitrile derivative ( 2 ) and the azine derivative ( 3 ) and/or the pyrazoloquinazoline derivative ( 4 ). When ( 4 ) was conducted to react either with EAA (ethyl acetoacetate) or Ac 2 O/AcOH (acetic anhydride/acetic acid) mixture or phthalic anhydride/acetic acid mixture, the pyrazoloquinazoline carbonitrile ( 5 ), pyrazolo‐quinazoline acetic acid ( 6 ) or the pyrazoloquinazolinone derivative ( 7 ) were formed respectively. When ( 1 ) was reacted with phenylhydrazine, a mixture of the quinazolinone derivative ( 8 ) and the hydrazone derivative ( 9 ) were obtained. The benzoxazinone derivative ( 1 ) was found also to react with benzylamine in ethanol or without solvent to give the quinazolinone derivative ( 10 ) or the quinazolindione ( 11 ) respectively. Fusion of ( 1 ) with ammonium acetate yielded the quinazolinone ( 12 ), which was methylated to give ( 13 ) and thiated to the thioxyquinazoline derivative ( 14 ), while reaction of ( 1 ) with formamide gave the N ‐formylquinazoline derivative ( 15 ).