<span style="font-size:12.0pt;font-family: "Times New Roman";mso-fareast-font-family:"Times New Roman";mso-ansi-language: EN-IN;mso-fareast-language:EN-IN;mso-bidi-language:AR-SA" lang="EN-IN">Some reactions of 2-phenyl-4(3<i style="mso-bidi-font-style:normal">H</i>)-quinazolinones</span>

850-853<span style="font-size:12.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-in;mso-fareast-language:en-in;mso-bidi-language:ar-sa"="" lang="EN-IN">Reaction of 2-phenyl-3, 1-benzoxazin-4H-one 1 with thiocarbohydrazide in refluxing ethanol affords 2-phenyl-3- thiosemicarbazido-4(3<i style="mso-bidi-font-style: normal">H)-quinazolinone 2. However, thioxotetrazinoquinazo line 3 is obtained in 79% isolated yield when the reaction mixture is fused in an oil bath at 160°C. Compound 3 is also obtained when compound 2 is heated in an oil bath at 170°C. On the other hand , compound <b style="mso-bidi-font-weight: normal">3 reacts with paraformaldehyde and secondary amines to afford the corresponding quinazoline derivatives 4 and 5. The diazonium salt of 3-amino-2-phenyl- 4(3H)-quinazolinone 6 reacts with some active methylene compounds (diethyl malonate, ethyl acetoacetate, malononitrile and acetyl acetone) to affords the quinazolinone derivatives 8-11 in good yields. Reactions of 8 with hydrazine hydrate and phenyl hydrazine afford the corresponding pyrazolonoquinazolinones 12 and <b style="mso-bidi-font-weight: normal">13, respectively. Reaction of 8 with urea furnishes pyrimidinoquinazolinones <b style="mso-bidi-font-weight: normal">14 in 79% isolated yield. However, reaction of 11 with hydrazine hydrate gives pyrazoloquinazolinones 15 in 83% isolated yield.