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The reaction of an isolable anionic aluminabenzene with electrophiles, such as MeOTf and Me 3 SiOTf, was investigated. The nucleophilic attack on the pentadienyl moiety of the aluminabenzene ring proceeded at the 4position to form the aluminacyclohexadiene bearing a Me or Me 3 Si group. Treatment of the resulting methyl-or silylsubstituted aluminacyclohexadiene with the bulky base MesLi gave the rearomatized anionic aluminabenzene bearing a Me or Me 3 Si group. Thus, this sequential reaction would be considered as an electrophilic substitution of aluminabenzene. The substituent effect of Me and Me 3 Si groups on the aluminabenzene ring was also estimated on the basis of experimental and theoretical studies.

Methyl 13(1)-(di)cyanomethylene-pyropheophorbides were synthesized by Knoevenagel reactions of the corresponding 13(1)-oxo-chlorins prepared from modifying chlorophyll-a with malononitrile or cyanoacetic acid. Alternatively, methyl 13(1)-cyanomethylene-pyropheophorbides were produced by Wittig reactions of 13(1)-oxo-chlorins with Ph3P=CHCN. Self-aggregation of zinc complexes of the semi-synthetic chlorophyll derivatives possessing a hydroxy or methoxy group at the 3(1)-position was examined in 1%(v/v) tetrahydrofuran or dichloromethane and hexane by electronic absorption and circular dichroism spectroscopy. Although intermolecular hydrogen-bonding between the 3(1)-hydroxy and 13(1)-oxo groups of bacteriochlorophylls-c/d/e/f was essential for their self-aggregation in natural light-harvesting antenna systems (=chlorosomes), zinc 3(1)-hydroxy-13(1)-di/monocyanomethylene-chlorins self-aggregated in the less/lesser polar organic solvents to form chlorosome-like large oligomers in spite of lacking the 13(1)-oxo moiety as the hydrogen-bonding acceptor. Zinc 3(1)-methoxy-13(1)-dicyanomethylene-chlorin gave similar self-aggregates regardless of lack of both the 3(1)-hydroxy and 13(1)-oxo groups. The present self-aggregation was ascribable to stronger coordination of the 3(1)-oxygen atom to the central zinc than the conventional systems, where the electron-withdrawing cyano group(s) increased the coordinative ability of the central zinc through the chlorin π-system.