title: Chromene-Annulated Bacteriochlorins.
abstract: Syntheses and optical properties of mono- and bis-chromene-annulated bacteriochlorins are described. Known monochromene-annulated meso-(pentafluorophenyl)chlorin is susceptible to a regioselective OsO4-mediated dihydroxylation, generating two monochromene-annulated trihydroxybacteriochlorin stereoisomers: either the newly introduced vic-cis-diol functionality is on the same side as the vic-cis-diol moiety the chromene-annulation was based on or on the opposite side. Treatment of the two isomers with heat or base generates different sets of bis-chromene-annulated bacteriochlorin stereo- and regioisomers. Detailed 1D and 2D (1)H and (19)F NMR spectroscopic investigations allowed the characterization of the isomers that formed. The regioselectivity of the second annulation reaction was rationalized computationally on steric grounds. The bacteriochlorin-type optical spectra of the mono- and bis-chromene-annulated bacteriochlorins are modulated as a result of the annulation, with each isomer possessing a unique spectrum, attributed to the effects the regiochemically distinct annulations have on the conformation of the chromophore. The formation of a bis-chromene-annulated chlorin from the bacteriochlorins is also described, including its X-ray crystal structure, revealing some details of the metrics of the chromene-annulated moiety. The vic-diol functionality of monochromene-annulated trihydroxybacteriochlorins is also susceptible to oxidation and ring-expansion reactions, generating chromene-annulated pyrrole-modified chlorins incorporating oxazolone and morpholine moieties. The work expands the body of work on the synthesis and optical fine-tuning of meso-aryl-substituted bacteriochlorins.
authors.affiliation: Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269-3060, United States.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Hyland
authors.affiliation: Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269-3060, United States.
authors.forename: Nisansala
authors.initials: N
authors.lastname: Hewage
authors.affiliation: Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269-3060, United States.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Panther
authors.affiliation: Department of Chemistry, Youngstown State University , One University Plaza, Youngstown, Ohio 44555-3663, United States.
authors.forename: Arunpatcha
authors.initials: A
authors.lastname: Nimthong-Roldán
authors.affiliation: Department of Chemistry, Youngstown State University , One University Plaza, Youngstown, Ohio 44555-3663, United States.
authors.forename: Matthias
authors.initials: M
authors.lastname: Zeller
authors.affiliation: Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269-3060, United States.
authors.forename: Milinda
authors.initials: M
authors.lastname: Samaraweera
authors.affiliation: Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269-3060, United States.
authors.forename: José A
authors.initials: JA
authors.lastname: Gascon
authors.affiliation: Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269-3060, United States.
authors.forename: Christian
authors.initials: C
authors.lastname: Brückner
mesh_terms: D001578:Benzopyrans / Q000138:chemical synthesis* / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D010081:Oxazolone / Q000737:chemistry*; D010084:Oxidation-Reduction; D011166:Porphyrins / Q000138:chemical synthesis / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry*; D005464:Fluorobenzenes; D005466:Fluorocarbons
chemical_list: D001578:Benzopyrans; D010081:Oxazolone; D011166:Porphyrins; D011758:Pyrroles; C452433:bacteriochlorin; C000621880:meso-(pentafluorophenyl)chlorin; D005464:Fluorobenzenes; D005466:Fluorocarbons; C006969:chlorin