<span style="font-size:19.5pt;mso-bidi-font-size:14.5pt; font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language:AR-SA">Synthesis of benzimidazo[1<i><span style="font-size:20.0pt;mso-bidi-font-size: 15.0pt;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language:AR-SA">,</span></i><span style="font-size:20.0pt;mso-bidi-font-size:15.0pt;font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";mso-ansi-language:EN-US;mso-fareast-language: EN-US;mso-bidi-language:AR-SA;mso-bidi-font-style:italic">2<i>-c </i><span style="font-size:19.5pt;mso-bidi-font-size:14.5pt;font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";mso-ansi-language:EN-US;mso-fareast-language: EN-US;mso-bidi-language:AR-SA">]quinazolines as possible bronchodilators^†</span></span></span>

434-439<span style="font-size:13.5pt;mso-bidi-font-size:8.5pt; font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">Synthesis of some 6-aryl-benzimidazo[1,2-c]quinazolines 4 have been critically investigated. The first method, based on the condensation of substituted- 1,3-benzoxazin-4-(3H)-one <b style="mso-bidi-font-weight: normal">2 with o-phenylenediamine followed by cyclization of the resulting 2-aryl-3-(2-aminophenyl) quinazolin-4(3H)one 3 by direct heating. A second (and new) method, based on dehydrocyclization of 2 with <i style="mso-bidi-font-style: normal">o-phenylenediamine in the presence of polyphosphoric acid provides a wide variety of the 6- arylbenzimidazo[1 ,2-<i style="mso-bidi-font-style: normal">c]quinazolines, usually in high yield. A third synthesis providing low yield involves dehydrocyclization of 2 with o-phenylenediamine by direct heating above its melting point. The structure of the compounds 4 have been established on the basis of their elemental analyses and spectral (IR, 1H NMR and mass) data. The bronchodilatory activity of compounds <b style="mso-bidi-font-weight: normal"><span style="font-size:14.0pt;mso-bidi-font-size:9.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">4a <span style="font-size:13.5pt; mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;="" mso-bidi-language:ar-sa"="">and 4b<span style="font-size:14.0pt; mso-bidi-font-size:9.0pt;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;="" mso-bidi-language:ar-sa"=""> <span style="font-size:13.5pt;mso-bidi-font-size: 8.5pt;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">is reported using in vitro and in vivo animals models.