An efficient gold-catalyzed cyclization of 2-alkynylaldehyde cyclic acetals has been developed for the synthesis of indenone derivatives. A wide variety of functionalized indenone derivatives can be obtained in good-to-excellent yields. HMBC and NOESY NMR analyses and mechanistic elucidation experiments revealed that the cyclization occurs via a 1,5-H shift. The cyclic acetal group promoted the 1,5-H shift by activating the benzylic C–H bond and preventing the migration of the alkoxy group by tethering both alkoxy groups.

A microwave (MW)-assisted method for the continuous production of hydrogen from methylcyclohexane using platinum on spherical carbon beads has been developed, and its application to the efficient dehydrogenative aromatization of fully saturated cyclic alkanes, including piperidines as representative heterocycles, has been studied. Effective dehydrogenation was achieved by the construction of a highly intense energy field, which acted as a reactive site, on the irradiation of the carbon beads (CB) support. The reaction could be carried out with only 10-W single-frequency MWs. The catalyst system could be used continuously for at least 12 h without any loss of catalyst activity. Dehydrogenative aromatization could also be catalyzed and simple cyclohexane derivatives, as well as piperidine derivatives as representative N-heterocyclic alkanes, were tested.

The catalyst activities of various heterogeneous palladium catalysts supported by anatase-, rutile- and brookite-type titanium oxide for ligand-free Suzuki–Miyaura cross-coupling reactions of aryl chlorides were evaluated. Palladium acetate [Pd(OAc)2], supported on anatase-type titanium oxide (TiO2) via acetonitrile solution impregnation process without reduction [Pd/TiO2 (anatase-type)], demonstrated the highest catalyst activity in comparison to those of other titanium oxide (rutile- or brookite-type) supported Pd(OAc)2 without reduction and reduced Pd/TiO2 (anatase-type) [Pd(red)/TiO2 (anatase-type)]. Various aryl chloride and bromide derivatives were smoothly coupled with arylboronic acids including heteroarylboronic acids in the presence of 5–10 mol% Pd/TiO2 (anatase-type) without the addition of any ligands. Although the fresh Pd/TiO2 (anatase-type) catalyst was surprisingly comprised of ca. 1:2 mixture of palladium(II) and palladium(0) species according to X-ray photoelectron spectroscopy (XPS), in spite of no reduction process, significant further increment of palladium(0) species was observed during the Suzuki–Miyaura coupling reaction, and Pd/TiO2 (anatase-type) was converted into a catalyst, which contained palladium(0) species as the main component [ca. 1:5 mixture of palladium(II) and palladium(0) species]. Therefore, the reduction via the electron donation process to the palladium(II) species may have occurred during the reaction on anatase-type titanium oxide.

We developed a microwave-mediated continuous hydrogen production method from 2-PrOH using platinum on a spherical carbon-bead catalyst. The catalyst cartridge consisted of helical glass part, and straight glass part (helix−straight cartridge) was newly developed for the effective microwave heating of 2-PrOH in the presence of 5% Pt/CB. The microwave resonance was properly adjusted within 2.4−2.5 GHz using the helix−straight cartridge with the glass resonance-adjuster tube. The reaction was conducted by the irradiation of only 10 W of single-frequency microwaves and the catalyst was used continuously for at least 13 h without any loss of catalyst activity.

Palladium catalysts immobilized on cellulose particles (Pd/CLP) and on a cellulose‐monolith (Pd/CLM) were developed. These composites were applied as hydrogenation catalysts and their catalyst activities were evaluated. Although both catalysts catalyzed the deprotection of benzyloxycarbonyl‐protected aromatic amines (Ar‐N‐Cbz) and aromatic benzyl esters (Ar‐CO2Bn), only Pd/CLM could accomplish the hydrogenolysis of aliphatic‐N‐Cbz and aliphatic‐CO2Bn protective groups. The difference in the physical structure of the cellulose supports induced unique chemoselectivity. Aliphatic‐N‐Cbz and aliphatic‐CO2Bn groups were tolerated under the Pd/CLP‐catalyzed hydrogenation conditions, while Ar‐N‐Cbz, Ar‐CO2Bn, alkene, alkyne, azido and nitro groups could be smoothly reduced.