Tetrahedron Vol 4.5,No 13, pp 4263 to 4286, 1989 Pnnted m Great Bntam oo4@4020/89 s3.00+ 00 0 1989 Maxwdl Pergamon Macmdh pk NRW METHODOLOGY FOR THE PREPARATION OF QUINAZOLINB DERIVATIVES VIA TANDEM AZA-WITTIG/RBTEROCUMULENE-MRDIATBD ANNULATION. SYNTHESIS OF 4(3H)-QUINAZOLINONES, BENZMIDAZO[1,2-c]QUINAZOLINES, QUINAZOLINO[3,2-a]QUINAZOLINES AND BENZoTHIAZOLO[3,2-c]QUINAZOLINES1 Pedro Molina*, Mateo Ala]arin and Angel Vidal. Departamento de Quimica Organica, Facultad de Ciencias Universidad de Murcia, 30071 Murcia, Spain. Ma de la Conception Faces-Faces and Felix Hernhndez Cano. U. E. I. de Cristalografia, Instituto de Quimica Fisica "Rocasolano", Serrano 117, 28006 Madrid, Spain. (Received in UK 7 April zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPON 1989) Abstract - The aza-wittzg reaction of iminophosphoranes derived from N-substituted o-azidobenzamides, 2-lo-azidophenyl )-benzimidazole, -benzothia- zole or -3,1-benzoxazin-4-one with heterocumulenes leads to functionalized quinazol ines. Iminophosphoranes 2, derived from N-substituted o-azido- benzamides, react under ml Id conditions WI th isocyanates to form 4H-3,1-benzoxazine-4-imines 11 which are convert ed into 2-substituted- - 4 (3Hl-quinazol inones 12. Iminophosphoranes 9 also react with carbon disulfide - - and carbon dioxide to give the quinazolinones 13 and 14 respectively. - - Iminophosphorane 26, derived from 2-/o-azidophenyl lbenzimidazole, reacts with isocyanates, carbon disulfide and carbon dioxide to form 6-substituted benzzmidazo[l,P-clquinazolines 3, 28 and 29 respectively. In benzene at room - - temperature, iminophosphorane 21, reacts with I socyana t es yielding quinazolino[3,2-a]quinazolines 34. Compounds 34 can also be prepared from iminophosphorane 36 and isocyanates. - - Iminophosphorane 40 derived from - 2-(o-azidophenyllbenzothiazole reacts with aliphatic and aromatic isocyanates or isothiocyanates to give 7H-benzothiazolo[ 3,2-c ] quinazoline-7-imines 42. - Iminophosphorane 40 also reacts with carbon dioxide or carbon disulfide to - afford the corresponding isocyanate 43 or isothiocyanate 44. The molecular - - structures of lld and 42a have been determined by X-ray diffraction methods. The quinazoline skeleton, when selectively functionalized, is a building block for the preparation of numerous alkaloids and substances capable of exhibiting a wide variety of biological activities. In the course of our 4263