Shigeru Yamaguchi

Synthesis of directly connected BODIPY oligomers through Suzuki-Miyaura coupling.

Treatment of a meso-arylboron dipyrrin (BODIPY) with NBS provides mono- and dibrominated BODIPYs at the 2- and 6-positions in excellent yields with high regioselectivity. Brominated products can be employed as a nice building block for the synthesis of a variety of BODIPY derivatives through Suzuki-Miyaura coupling. Because of a lack of substituents at the 1,3,5,7-positions, a directly β-β-linked BODIPY dimer exhibits a completely coplanar conformation of BODIPY units, offering effective π-conjugation.

Facile Synthesis of Biphenyl-Fused BODIPY and Its Property

A biphenyl-fused BODIPY was synthesized through a facile oxidative cyclization of peripheral aryl-substituents at the β-position of the BODIPY unit. The extended π-system of the fused BODIPY induces near-infrared (NIR) absorption and strong π-π interactions in the solid state. These features are beneficial for the application of the dye as a functional material. The biphenyl-fused BODIPY dye was demonstrated to exhibit photocurrent conversion ability on the basis of its n-type semiconducting property.

Dimeric assemblies from 1,2,3-triazole-appended Zn(II) porphyrins with control of NH-tautomerism in 1,2,3-triazole.

Cu(I)-catalyzed 1,3-dipolar cycloaddition of meso-ethynyl Zn(II) porphyrin with benzyl azide efficiently provides meso-1-benzyl-1H-1,2,3-triazolyl Zn(II) porphyrin, which assembles to form a slipped cofacial dimer by the complementary coordination of the triazole nitrogen atom at the 3-position to the zinc center of a second porphyrin moiety both in the solid and solution states. Removal of the benzyl protection and introduction of a 2-ethoxycarbonylphenyl moiety greatly stabilize the dimeric assembly through an additional hydrogen bonding interaction between the NH proton of 2H-1,2,3-triazole and the carbonyl oxygen.

Pt(II)- and Pt(IV)-Bridged Cofacial Diporphyrins via Carbon−Transition Metal σ-Bonds

A directly Pt(IV)-bridged cofacial diporphyrin has been synthesized by the cyclometalation reaction of beta-pyridylporphyrin with a Pt(IV) salt. Upon treatment with methylhydrazine, the Pt(IV) bridge is reduced to the Pt(II) center, resulting in a Pt(II)-bridged cofacial dimer with a helicity inversion of the complex as well as change in electronic communication through the metal bridge.

Synthesis of Nickel(II) Azacorroles by Pd‐Catalyzed Amination of α,α′‐Dichlorodipyrrin NiII Complex and Their Properties

Synthesis of nickel(II) complexes of meso-aryl-substituted azacorroles was performed by Buchwald-Hartwig amination of a dipyrrin Ni(II) complex with benzylamine through C-N and C-C coupling. The highly planar structure of Ni(II) azacorroles was elucidated by X-ray diffraction analysis. (1)Hu2005NMR analysis and nucleus independent chemical shift (NICS) calculation on Ni(II) azacorrole revealed its distinct aromaticity with [17]triaza-annulene 18π conjugation. In addition, acylation of azacorrole selectively afforded N- and C-acylated azacorroles depending on the reaction conditions, showing the dual reactivity of azacorroles.

Synthesis of Thieno-Bridged Porphyrins: Changing the Antiaromatic Contribution by the Direction of the Thiophene Ring

Two types of thieno-bridged porphyrins were synthesized by incorporating a thiophene group across their meso and β positions with different directions of the thiophene ring to investigate the aromaticity of these porphyrins with extended π-systems. The 2,3-thieno-bridged porphyrin showed a larger antiaromatic contribution than did the 3,4-thieno-bridged porphyrin. In the former, the antiaromatic contribution is based on a 20-π-electron conjugated circuit. The two thieno-bridged porphyrins were characterized by calculations of nucleus-independent chemical shift and anisotropy of the induced current density as well as by X-ray crystallography, NMR spectroscopy, UV-vis-NIR absorption spectroscopy, electrochemical studies, time-resolved excited-state analysis, and two-photon absorption cross section measurements. Chemical derivatization of the 2,3-thieno-bridged porphyrin was also demonstrated.

meso-Thiaporphyrinoids Revisited: Missing of Sulfur by Small Metals

Facile synthesis of meso-aryl-substituted 5,15-dithiaporphyrins and 10-thiacorroles has been achieved by sulfidation of α,α-dichlorodipyrrin metal complexes with sodium sulfide in DMF. Thiacorrole metal complexes exhibit distinct aromaticity due to 18u2009π-conjugation including the lone pair on sulfur, whereas dithiaporphyrins are nonaromatic judging from (1)Hu2005NMR spectra, X-ray analysis, and absorption spectra. We have found that Ni(II) and Al(III) dithiaporphyrin complexes undergo smooth thermal sulfur extrusion reaction to give the corresponding thiacorrole complexes, whereas free base, Zn(II), Pd(II), and Pt(II) dithiaporphyrin complexes did not exhibit the similar reactivity. The DFT calculations have elucidated a reaction pathway involving an episulfide intermediate, which can explain the markedly different reactivity among dithiaporphyrin metal complexes.

Synthesis of a diimidazolylporphyrin pincer palladium complex

A novel NCN type palladium pincer complex based on the porphyrin backbone was synthesized. The palladium atom bound to the meso-carbon of the porphyrin core was effectively supported by two imidazolyl groups. The product was characterized by spectroscopic and X-ray diffraction analysis. The structure of the porphyrinic macrocycle was revealed to be highly distorted by the coordination of the outer palladium center. The degree of deformation was found to be even larger than the analogous palladium pincer complexes in which pyridine groups were employed as the supporting ligands. The complex exhibited high catalytic activity in the Mizoroki-Heck reaction of iodobenzene with butyl acrylate with 0.005% of the catalyst loading.

η2-Porphyrin Ru(II) π Complexes

Highly stable eta(2)-porphyrin Ru(II) pi complexes have been synthesized. The formation of the eta(2) pi bond has been facilitated through pi-pi stacking interactions between the porphyrin and the planar ligand on Ru. pi coordination of ruthenium to porphyrin results in dramatic changes in the aromaticity and electronic properties. These properties are controllable via fine-tuning of the ligand on ruthenium.

CCDC 843983: Experimental Crystal Structure Determination

Related Article: Y.Hayashi, S.Yamaguchi, Won Young Cha, Dongho Kim, H.Shinokubo|2011|Org.Lett.|13|2992|doi:10.1021/ol200799u