title: Synthesis of 6H-indolo[2,3-b][1,6]naphthyridines and related compounds as the 5-Aza analogues of ellipticine alkaloids.
abstract: Treatment of 2-(1-alkynyl)phenyl isocyanates 6 with the iminophosphorane 14 produced in situ the benzoenynyl carbodiimides 15. Thermolysis of 15 under refluxing p-xylene furnished the 6H-indolo[2,3-b][1,6]naphthyridines 5, which could be regarded as the 5-aza analogues of ellipticine alkaloids. Similarly, condensation of 6 with the iminophosphorane 20 led to the formation of the 6H-indolo[2,3-b][1,5]naphthyridines 25 as the major isomer and the 10H- indolo[2,3-b][1,7]naphthyridines 26 as the minor isomer. The indolonaphthyridines 32, 33, and 34 having a methoxyl substituent were likewise synthesized. Treatment of the diisocyanate 43 with 2 equiv of the iminophosphorane 7 furnished 45 having two indoloquinoline units incorporated in a seven-fused-ring system.
authors.affiliation: Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Zhang
authors.forename: C
authors.initials: C
authors.lastname: Shi
authors.forename: H R
authors.initials: HR
authors.lastname: Zhang
authors.forename: K K
authors.initials: KK
authors.lastname: Wang
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis*; D001372:Aza Compounds / Q000138:chemical synthesis*; D004611:Ellipticines / Q000138:chemical synthesis*; D009287:Naphthyridines / Q000138:chemical synthesis*
chemical_list: D000970:Antineoplastic Agents; D001372:Aza Compounds; D004611:Ellipticines; D009287:Naphthyridines; C034192:ellipticine