title: Preparation of dibenzo[e,g]isoindol-1-ones via Scholl-type oxidative cyclization reactions.
abstract: A flexible synthesis of dibenzo[e,g]isoindol-1-ones has been developed. Dibenzo[e,g]isoindol-1-ones represent simplified benzenoid analogues of biological indolo[2,3-a]pyrrolo[3,4-c]carbazol-5-ones (indolocarbazoles), compounds that have demonstrated a wide range of biological activity. The synthesis of the title compounds involved tetramic acid sulfonates. Different aryl groups were introduced at C4 of the heterocyclic ring via Suzuki-Miyaura cross-coupling reactions. Finally, mild Scholl-type oxidative cyclizations mediated by phenyliodine(III) bis(trifluoroacetate) (PIFA) converted some of the latter compounds into the corresponding dibenzo[e,g]isoindol-1-ones. A systematic study of the oxidative cyclization revealed the following reactivity trend: 3,4-dimethoxyphenyl ≫ 3-methoxyphenyl > 3,4,5-trimethoxyphenyl > 4-methoxyphenyl ≈ phenyl. Overall, the oxidative cyclization required at least two methoxy groups distributed in the aromatic rings, at least one of which had to be located para to the site of the cyclization.
authors.affiliation: Department of Chemistry, Hobart and William Smith Colleges , Geneva, New York 14456, United States.
authors.forename: Amy A
authors.initials: AA
authors.lastname: van Loon
authors.forename: Maeve K
authors.initials: MK
authors.lastname: Holton
authors.forename: Catherine R
authors.initials: CR
authors.lastname: Downey
authors.forename: Taryn M
authors.initials: TM
authors.lastname: White
authors.forename: Carly E
authors.initials: CE
authors.lastname: Rolph
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Bruening
authors.forename: Guanqun
authors.initials: G
authors.lastname: Li
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Delaney
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Pelkey
authors.forename: Erin T
authors.initials: ET
authors.lastname: Pelkey
mesh_terms: D003500:Cyclization; D054833:Isoindoles / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D010084:Oxidation-Reduction
chemical_list: D054833:Isoindoles