Haruhiko Takeya

Synthesis of p-tert-Butylthiacalix[4]arene and its Inclusion Property

Abstract A practical method for the synthesis of p-tert-butylthiacalix[4]arene (TC4A), in which the methylene bridges of p-tert-butylcalix[4]arene (C4A) are replaced by epithio groups, is presented by heating a mixture of p-tert-butylphenol, elemental sulfur S8, and NaOH as a base catalyst in tetraethylene glycol dimethyl ether. The inclusion behavior of TC4A for a wide range of solvent molecules is examined by recrystallization, showing preference for the guests depending upon the size and/or the substituent of the guests. The X-ray structure of a 1:2 host–guest complex of TC4A with 1,2-dichloroethane reveals that one guest molecule is included in the cavity of TC4A, while the other is included in the crystal lattice to form a clathrate-type complex. It is shown that the inclusion in the cavity is attained by a cooperative deformation of both the host and the guest.

Crystal structure and inclusion property of p-tert-butylthiacalix[6]arene

Abstract Although the reaction of p-tert-butylphenol with elemental sulfur in the presence of CsOH as a base catalyst yielded a complex mixture comprised of sulfur-bridged phenol oligomers, p-tert-butylthiacalix[6]arene (TC6A) could be isolated in an appreciable yield (0.8%). The X-ray analysis revealed that TC6A adopted a distorted cone conformation stabilized by two sets of hydrogen bondings comprising three phenolic OH groups. The recrystallization from various solvents showed that TC6A had higher inclusion ability toward more guests than TC4A did, suggesting that the expanded central cavity and/or the crystal lattice of the former allowed a more comfortable accommodation of the guest molecules.

Photooxygenation of stilbenes in zeolite by excitation of their contact charge transfer complexes with oxygen

Abstract Contact charge transfer (CCT) complexes of trans -stilbenes with oxygen molecules were formed in zeolite NaY. Excitation of the CCT bands by a 313-nm wavelength light produced the corresponding benzaldehydes through an electron transfer reaction to generate stilbene cation radicals and superoxide anion radical. Irradiation of the CCT complexes by a 254-nm wavelength light, by contrast, gave rise to isomerization and formation of phenanthrene without yielding any oxygenation products, as in the photoreaction under oxygen in solution.

A new synthesis of 5-aminolevulinic acid via dye-sensitized oxygenation of N-furfurylphthalimide

Abstract Dye-sensitized oxygenation of N-furfurylphthalimide using Rose Bengal, fullerene-C 60 , and coronene as sensitizers yielded 5-phthalimido-4-oxopentenoic acid. The acid was then hydrogenated with palladium-on-carbon, and was hydrolyzed to finally produce 5-aminolevunilic acid ( 1 ) at about 50% total yield. The oxygenation process was studied in relation to the mechanistic process and the improvement of yield, using several solvent systems and 2,3-dimethyl-2-butene, and was explained as a singlet oxygen reaction. The synthesis method used for 1 was an improvement on previously reported methods with respect to: the total yield, the commercial availability of the starting materials, and the economical nature of the oxygenation process, even on a large scale.