title: Introduction of a third meso substituent into 5,10-diaryl chlorins and oxochlorins.
abstract: Chlorins/oxochlorins bearing distinct patterns of substituents are valuable compounds in bioorganic and materials chemistry. Treatment of a 5,10-diaryl-substituted chlorin or oxochlorin with TFA-d(1) resulted in selective deuteriation of the remaining meso positions (15, 20) rather than any of the beta-pyrrolic positions. Electrophilic iodination or bromination of a 5,10-diaryl-substituted chlorin proceeded with high regioselectivity, affording the 5,10-diaryl-15-halo-substituted chlorin. Iodination or bromination of a free base 5,10-diaryloxochlorin gave a mixture of products arising through halogenation at the 15-, 20-, and beta-pyrrolic positions, while bromination of a zinc 5,10-diaryloxochlorin selectively gave the 5,10-diaryl-20-bromo-substituted oxochlorin. The Suzuki coupling reaction of a phenyl boronic acid derivative and a 5,10-diaryl-15-iodooxochlorin or 5,10-diaryl-20-bromooxochlorin gave the corresponding 5,10,15- or 5,10,20-triaryloxochlorin. The introduction of a third aryl substituent into the chlorin or oxochlorin causes an approximately 5-nm red shift of the long wavelength Q(y) absorption band. Two phenylethyne-linked oxochlorin-oxochlorin dyads in distinct metalation states (zinc/free base, free base/zinc) were prepared by Sonogashira coupling reactions of a 5,10-diaryl-20-bromooxochlorin and a 10-substituted ethynylphenyl oxochlorin. This study provides access to new chlorins/oxochlorins that can be utilized in diverse applications.
authors.affiliation: Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Taniguchi
authors.forename: Man Nyoung
authors.initials: MN
authors.lastname: Kim
authors.forename: Doyoung
authors.initials: D
authors.lastname: Ra
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Lindsey
mesh_terms: D002384:Catalysis; D006846:Hydrocarbons, Halogenated / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008665:Metalloporphyrins / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry; D011166:Porphyrins / Q000138:chemical synthesis* / Q000737:chemistry; D015032:Zinc / Q000737:chemistry*
chemical_list: D006846:Hydrocarbons, Halogenated; D008665:Metalloporphyrins; D011166:Porphyrins; C006969:chlorin; D010165:Palladium; D015032:Zinc