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The first enantioselective Pictet-Spengler reaction of acyclic α-ketoesters with tryptamines has been developed. Excellent yields and enantioselectivity were obtained for the reaction using chiral imidazoline-phosphoric acid catalysts. Density functional theory calculations suggested possible transition states that explain the origin of chiral induction. This process provides an efficient route for the synthesis of tetrahydro-β-carboline derivatives.

Asymmetric aza-Henry reaction of cyclic ketimines, which are easily prepared by the oxidation of commercially available cyclic amino acids with nitroalkanes was accomplished by using our original cinchona alkaloid sulfonamide/zinc(ii) catalyst.

This paper provides the first report of the intramolecular [2+2] cycloaddition of vinylsilane. The [2+2] cycloaddition of allenes is a useful reaction that can synthesize cyclobutanes. However, no previous works have attempted to control the regioselectivity between the two double bonds of allenes only by changing the reaction conditions, although there have been some reports of the regioselective [2+2] cycloaddition of allenes by changing the substrate. In this study, we have succeeded in controlling intramolecular [2+2] cycloaddition reactions at the proximal and distal positions of allenes simply by changing the reaction conditions. We found that the atomic radius of silicon is very important for perfect control of the reaction's sites. The structures of all key compounds were determined by the crystal sponge method which could identify the structures of liquid compounds.

The first enantioselective hydrophosphonylation of ketimines with phosphine oxides was developed. The reaction of unprotected ketimines with phosphine oxides using a bis(imidazoline)-phosphoric acid catalyst gave chiral α-quaternary aminophosphorous compounds having a primary amino group in excellent yields and enantioselectivities. Based on experimental results and DFT calculation, transition states were proposed to explain the stereoselectivity of the reaction.

We have developed a one-iridium-catalyst system that transforms N-allyl-N-sulfonyl-2-(silylalkynyl)aniline derivatives, which are 1,7-enynes in which both multiple bonds have a heteroatom, to the corresponding substituted indole derivatives via isomerization/cycloisomerization/aromatization. This strategy provides an atom-economical and straightforward synthetic approach to a series of valuable indoles having vinyl and silylmethyl groups at the 2- and 3-positions.

We have developed a continuous microwave irradiation-assisted Buchwald–Hartwig amination using our original Pd nanoparticle catalyst with a copper plate as a co-existing metal solid. In this methodology, a microwave-controlled product selectivity was achieved between Buchwald–Hartwig amination and aryne amination performed under strongly basic conditions and at a high reaction temperature, because a polar chemical species such as Ar–Pd–halogen might be activated selectively by microwave radiation. Moreover, our catalyst could be used repeatedly over 10 times, and the amount of Pd leaching could be suppressed to a low level.

The first enantioselective aza-Henry reaction of non-activated cyclic iminoesters, derived from cyclic amino acids, has been developed. Good yields and enantioselectivities were observed for the reaction using our original cinchona alkaloid sulfonamide/zinc(II) catalyst. The transition state was proposed to explain the stereoselectivity based on experiments and DFT calculations.

We have developed a one-iridium-catalyst system that transforms

[Image: see text] We designed and synthesized a novel 1,2-deoxy-pyranose and terminal epoxide methyl substituted derivatives of spliceostatin A using Julia–Kocienski olefination as a key step. With respect to the biological activity, the 1,2-deoxy-pyranose analogue of spliceostatin A suppressed AR-V7 expression at the nano level (IC(50) = 3.3 nM). In addition, the in vivo toxicity test showed that the 1,2-deoxy-pyranose analogue was able to avoid severe toxicity compared to spliceostatin A.

To achieve a complete closed-shell quinoidal state, bis(dicyanomethylene)-substituted quinoidal terthiophenes bearing benzene annelation at all thiophene rings were synthesized using a retro-Diels–Alder reaction as the key step. The unique structures and properties originating from the full benzene annelation were revealed by X-ray analysis as well as property measurements. Organic solar cells based on the combination of a donor polymer with a quinoidal terthiophene as an acceptor showed a power conversion efficiency of 1.39%.

A nanoparticle (NP)-based precatalyst has been developed for organic synthesis: sulfur-modified Au-supported Fe (SAFe). The SAFe was easily prepared through a three-step procedure involving simultaneous in situ metal NP and nanospace organization (PSSO). This method avoids the need for preformed templates for immobilizing and stabilizing the metal nanoparticles. On account of the relative safety and enormous earth abundance of iron, SAFe potentially represents an ideal precatalyst for carbon–carbon bond-forming cross-coupling reactions. As such, it has been applied as a precatalyst to Kumada coupling under ligand-free conditions, proving to be capable of being recycled and used repeatedly for this reaction. Analysis of SAFe and of reaction mixtures suggested that the active species in these reactions are produced in situ by assemblies of iron-based NPs.

The synthesis of helically chiral [6]helicene-based sulfonic acid and sulfonamide from enantiomerically pure 1-acetylthio-5,6,9,10-tetrahydro[6]helicene is reported. The first helically chiral disulfonimides were developed as a synthetic application of [6]helicene-based sulfonamide. This new class of organocatalysts was tested in an asymmetric Mukaiyama aldol reaction to obtain up to quantitative yields and enantioselectivities up to 24%.

N-propylsulfanyl and isopropylsulfanyl substituted 2,5-di(1,3-dithiol-2-ylidene)-1,3-dithiolane-4-thione derivatives with methoxycarbonyl groups were synthesized, and their redox and electronic properties and crystal structures were investigated. Solid-state absorption spectra showed that both derivatives absorb almost all visible light. Furthermore isopropylsulfanyl-substituted derivatives absorb near-infrared light and the absorption edge reaches around 1320 nm. The crystal structures show that both derivatives are stacked in one dimension to form a columnar structure, but the molecular arrangements of their columns were quite different from each other. The stacked n-propylsulfanyl derivatives kept their orientation of thiocarbonyl groups in the same direction and the one molecule of the isopropylsulfanyl derivatives were rotated in relation to each other by an angle of 56° about their longer molecular axis. The TD-DFT calculation of stacked molecules suggests that the molecular arrangement among the st...

We have developed two novel, isomeric compounds of phenyl-substituted dinaphtho[2,3-b:2′,3′-d]furan (Ph-DNF-VW and Ph-DNF-VV) using a facile synthetic protocol. Notably, Ph-DNF-VW has been shown to...

A new class of solution-processable thieno[3,2-f:4,5-f′]bis[1]benzothiophene (TBBT-V) semiconductors are investigated. Semiconductors with decyl substituents and two kinds of π-extended decylthienyl substituents are facially derivatized from functionalized dibromo-substituted TBBT-Vvia either a Negishi or a Stille cross coupling procedure. The solubilities of TBBT-V semiconductors are somewhat higher than those of their previously developed dinaphtho[2,3-b:2′,3′-d]thiophene (DNT-V) counterparts. Single crystal analysis together with a calculation study on the transfer integral and the band structure in decyl-substituted TBBT-V (C10-TBBT-V) clarifies that these semiconductors form two-dimensionally ordered herringbone packing structures and the effective mass in the columnar direction rivals that of the previously developed decyl-substituted DNT-V. The carrier mobilities of TBBT-V derivatives in solution grown into single-crystalline films are remarkable (up to 6.2 cm2 V−1 s−1). Furthermore, their operation voltages are apparently lower than those of previously developed DNT-V derivatives due to the optimized ionization potential of the TBBT-V core and further π-extension by substitution of the thienyl groups.

We have synthesized and theoretically calculated 5-methylisoindolo[2,1-a]quinoline derivatives as novel near-infrared absorption dyes via a ruthenium-catalyzed one-pot metathesis/oxidation/1,3-dipolar cycloaddition protocol. The reactivity in 1,3-dipolar cycloaddition was governed by the electronic effect of aromatic ring substituents. Substrates with an electron-withdrawing group on the aromatic ring afforded higher yields. The maximal absorption wavelength of 3,5-dimethyl-11-phenylisoindolo[2,1-a]quinoline-7,10-dione and 11-(4-methoxyphenyl)-5-methylisoindolo[2,1-a]quinoline-7,10-dione in MeOH increased to 736 and 737 nm, although that of 3a was 727 nm.

Two 1-[6]helicenol derivatives were synthesized by Ni-catalyzed [2+2+2] cycloaddition on a multigram scale. Both enantiomers of the 1-[6]helicenols could be efficiently prepared by simple optical resolution. As a synthetic application of helically chiral 1-[6]helicenols, a novel class of [6]helicene-based phosphinites was developed; these compounds represent the first examples of helically chiral phosphinite ligands. Up to 90 % ee was obtained for the Pd-catalyzed asymmetric allylic alkylation reaction.

N-Alkyl-N-(2-vinylbenzyl)prop-2-en-1-amine derivatives undergo a one-pot olefin isomerization/aliphatic enamine ring-closing metathesis (RCM)/oxidation/1,3-dipolar cycloaddition sequence with the ruthenium complex, Ru(CO)HCl(PPh3)3, a second generation Hoveyda–Grubbs catalyst, and a 1,3-dipolarophile. Overall, in a single operation the reaction sequence converts simple benzylamine derivatives into isoindolo[1,2-a]isoquinolines with a π-conjugated four-ring system, through three unique ruthenium-catalyzed transformations.

The one-pot reactions of catalytically generated bicyclic zinc enolate with various electrophiles are reported. The zinc enolate as a key intermediate is efficiently delivered from Ni-catalyzed reductive cyclization of alkynyl cyclohexadienone. Employing aldehydes, imine, nitroalkene, and α,β-unsaturated carbonyl compounds as electrophiles, this new class of one-pot reactions gave multi-functionalized cis-hydrobenzofurans and octahydro-4,7-ethanobenzofuran-9-one derivatives in moderate to good yields.

N-Alkyl-N-(2-vinylbenzyl)prop-2-en-1-amine derivatives undergo a one-pot olefin isomerization/aliphatic enamine ring-closing metathesis (RCM)/oxidation/1,3-dipolar cycloaddition sequence with the ruthenium complex, Ru(CO)HCl(PPh3)3, a second generation Hoveyda–Grubbs catalyst, and a 1,3-dipolarophile. Overall, in a single operation the reaction sequence converts simple benzylamine derivatives into isoindolo[1,2-a]isoquinolines with a π-conjugated four-ring system, through three unique ruthenium-catalyzed transformations.