title: 2,3,17,18-Tetrahalohexaphyrins and the first phlorin-type hexaphyrins.
abstract: 1-(Triisopropylsilyl)-3,4-dichloropyrrole and 1-(triisopropylsilyl)-3,4-difluoropyrrole were conveniently prepared from the corresponding 3,4-dibromopyrrole by lithiation followed by halogenation. 2,3,17,18-Tetrahalogeno [26]- and [28]hexaphyrins have been prepared by condensation of 3,4-dihalopyrroles and a dipyrromethane-dicarbinol. 2,3,17,18-Tetrahalogenated hexaphyrins display variable structural and electronic properties depending upon the halogen atom and the number of π-electrons. Tetrabromo[28]hexaphyrin and tetrachloro[28]hexaphyrin were further reduced with excess NaBH4 to furnish meso-reduced hexaphyrins as the first example of phlorin-type meso-aryl-substituted hexaphyrins.
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Higashino
authors.forename: Atsuhiro
authors.initials: A
authors.lastname: Osuka
keywords: aromaticity; expanded porphyrins; halogenation; hexaphyrin; phlorin