Takashi Murashima

Synthesis and optical properties of a new class of pyrromethene–BF2 complexes fused with rigid bicyclo rings and benzo derivatives

Abstract A new class of boron dipyrromethene (BDP) dyes fused with rigid bicyclo[2.2.2]octadiene units are prepared, which are converted into benzo BDP dyes via a retro Diels–Alder reaction; the absorption and fluorescence spectra of the new dyes are discussed.

A new synthesis of benzoporphyrins using 4,7-dihydro-4,7-ethano-2H-isoindole as a synthon of isoindole

Heating 4,7-dihydro-4,7-ethano-2H-isoindole at 200 °C induces the retro-Diels–Alder reaction to give isoindole in essentially quantitative yield, which can be applied to a new synthesis of tetrabenzoporphyrins and monobenzoporphyrins.

Synthesis of benzoporphyrins functionalized with octaester groups

Abstract Benzoporphyrins with octamethoxycarbonyl groups 8a,b are obtained in near 100% yields by heating the corresponding tetra(bicyclo)porphyrins 7a,b at 200°C without affecting the ester moiety.

The first preparation of crown ether-annulated porphyrin

Abstract Pyrroles fused with crown ethers are prepared by the reaction of 3,4-dihydroxy pyrrole 1 and polyethylene glycol ditosylate 2 in the presence of cesium fluoride using a convenient high dilution method. These pyrroles can be converted into the corresponding porphyrins with four crown ether moieties, which are expected to form ion channels.

Ambident reactivity of nitro heteroaromatic anions

Two classes of nitro heteroaromatic compounds such as quinoxalines 7a,b and benzothiaselenadiazoles 7c,d with ethyl isocyanoacetate in the presence of 1,8-diazabicyclo[5,4,0]undec-7-ene g gave the corresponding pyrimidine N-oxides 8a-d, whilst, in contrast, use of proazaphosphatrane 2 or iminophosphorane 4 as a base under similar conditions gave the corresponding pyrroles 9a-d.

A new synthesis of [2,3]naphthoporphyrins

A new synthesis of [2,3]naphthoporphyrins using 4,9-ethano-2H-benz[f]isoindole as a synthon of 2H-benz[f]- isoindole is described; soluble precursors of [2,3]naphthoporphyrins are converted into insoluble [2,3]naphthoporphyrins by simply heating at 290 °C.

A new synthesis of pyrroles and porphyrins fused with aromatic rings

Pyrroles fused with aromatic rings (isoindole derivatives) have been readily prepared by the reaction of aromatic nitro compounds with ethyl isocyanoacetate in the presence of DBU. The ease of this reaction depends on the aromaticity of the starting nitro aromatics. Polycyclic aromatic nitro compounds such as 1-nitroacenaphthylene or 9-nitrophenanthrene are more reactive than simple nitro aromatics such as nitrobenzene or nitronaphthalenes and give the corresponding pyrroles in good yields. Pyrroles prepared by this method have been converted into porphyrins fused with various aromatic rings by the reduction with LiAlH4 followed by treatment with an acid catalyst and oxidation with chloranil or oxygen. Tetra-1,2-naphthoporphyrin has been prepared by the reaction of 2-nitro-3,4-dihydronaphthalene or 1-nitronaphthalene with ethyl isocyanoacetate followed by reduction, tetramerization and oxidation. Thus, highly conjugated porphyrins are readily prepared starting from aromatic nitro compounds, and their electronic and optical properties can be controlled by choice of the starting aromatic nitro compound.

Synthesis and properties of polypyrrole annelated with bicyclo(2.2.2)octene units

Abstract Polypyrrole annelated with bicyclo[2.2.2]octene provides a new material that possesses a raised HOMO band, extended conjugation and a rigid porous structure.

Synthesis and structures of pyrroles fused with rigid bicyclic ring systems at β-positions

Pyrroles fused with bicyclo[2.2.2]octene and bicyclo[2.2.1]heptene frameworks are prepared by a modified Barton–Zard method. Structures of these pyrroles and thermal behaviours of the former pyrroles are studied by X-ray and DSC analyses.

Synthesis of a gable bis-porphyrin linked with a bicyclo[2.2.2]octadiene ring and its conversion into a conjugated planar bis-porphyrin

A soluble porphyrin dimer linked with bicyclo[2.2.2]octadiene was converted into insoluble conjugated porphyrin dimer by heating at 200 °C, this provides a new strategy for the process control of conjugated porphyrins.