title: Exploitation of a tuned oxidation with N-haloimides in the synthesis of caulibugulones A-D.
abstract: Marine alkaloids caulibugulones A-D were synthesized in six steps starting from the readily available 2,5-dimethoxybenzaldehyde. Pomeranz-Fritsch reaction of N-(2,5-dimethoxybenzyl)-N-(2,2-dimethoxyethyl)-2-nitrobenzenesulfonamide proceeded smoothly to give 5,8-dimethoxyisoquinoline, which was oxidized to isoquinolinediones by a tunable oxidation reaction with N-haloimides. Therefore, NBS furnished direct conversion to the isoquinoline-5,8-dione; alternatively, N-haloimides of cyanuric acid provided both oxidation and halogenation generating 6,7-dihaloisoquinoline-5,8-diones. Aminolyses of these isoquinolinediones with methylamine or ethanolamine produced the isoquinolinedione alkaloids caulibugulones A-D in 24-57% overall yield.
authors.affiliation: Institute of Chemistry, State University of Campinas, P.O. Box 6154, Campinas, SP, 13083 970, Brazil.
authors.forename: Fabrício F
authors.initials: FF
authors.lastname: Naciuk
authors.forename: Julio C
authors.initials: JC
authors.lastname: Milan
authors.forename: Almir
authors.initials: A
authors.lastname: Andreão
authors.forename: Paulo C M L
authors.initials: PC
authors.lastname: Miranda
mesh_terms: D007094:Imides / Q000737:chemistry*; D007546:Isoquinolines / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011809:Quinones / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D007094:Imides; D007546:Isoquinolines; D011809:Quinones; C516625:caulibugulone A