Masahiro Noji

9,10-Disubstituted Octafluoroanthracene Derivatives via Palladium-Catalyzed Cross-Coupling

9,10-Dichlorooctafluoroanthracene (1) reacts with aryl boronic acids and terminal alkynes under palladium-catalyzed cross-coupling conditions to afford 9,10-diaryloctafluoroanthracenes (2a-e) and 9,10-dialkynyloctafluoroanthracenes (6a,b), respectively. Optical spectroscopy and cyclic voltammetry indicate that octafluoro-9,10-di(thiophen-2-yl)anthracene (2d) exhibits donor-acceptor character and a LUMO energy level of -3.27 eV relative to vacuum. A functionalized 5-bromothiophen-2-yl derivative (2e) was obtained in high yield by bromination of 2d with NBS. X-ray crystallographic analysis of octafluoro-9,10-bis[(trimethylsilyl)ethynyl]anthracene (6a) reveals a solid-state structure that mimics the packing of columnar liquid crystals, with a pi stacking distance of 3.39 A between the octafluoroanthracene cores. In addition, octafluoro-9,10-bis(mesitylethynyl)anthracene (6b) displays a LUMO energy level of -3.50 eV, which approaches the value of -3.65 eV measured for perfluoropentacene, making 9,10-dialkynyloctafluoroanthracenes a promising new class of n-type organic materials.

Photoreactions of β-aziridinylacrylonitrile. 1,3-Dipolar cycloadditions of photoinduced azomethine ylide

The photoinduced azomethine ylide A from the 3-(1-benzylaziridin-2-yl)prop-2-enenitrile 1 undergoes 1,3-dipolar cycloaddition with electron-deficient olefins to give the head-to-head adducts selectively and efficiently.

Regioselective β-silylation of porphyrins via iridium-catalyzed C–H bond activation

An efficient approach to meso-unsubstituted β-silylporphyrins was developed through highly regioselective Ir-catalyzed C-H activation, in the presence of HSiMe(OSiMe3)2 as the Si source, from meso-unsubstituted porphyrins. Further transformations of the silyl group, such as oxidation, halogenation, and cross-coupling reactions, could be achieved under mild conditions, demonstrating the synthetic utility of β-silylporphyrins as a multipurpose synthon for fabricating porphyrin derivatives.

Novel photoadditions of tertiary amines to the α-position of α,β-unsaturated γ,δ-epoxy nitriles

The photoreactions of α,β-unsaturated γ,δ-epoxy nitriles 1, 2, 13 and 16 with triethylamine give rise to novel 1 ∶ 1 α-adducts (e.g., 5) efficiently. After treatment with silica gel, the adducts undergo retro-Michael reaction leading to the corresponding α-alkylidenenitrile derivatives (e.g., 3). The epoxy nitrile 1 also reacts with various tertiary amines to afford α-adducts. The reaction of 1 and the silylamine 24 gives mainly methylene derivative 22 and silylated compound 25 after treatment with silica gel. The reaction may proceed via single- electron-transfer from the amine to the excited epoxy nitrile.