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Intermediary radical cations, generated through single-electron oxidation of enol silyl ethers by excited Ir-based photocatalysts, can be exploited as Brønsted acids for the activation of heteroarylcyanides. This strategy enables the direct allylic C-H heteroarylation of enol silyl ethers under visible-light irradiation.

Strategies for altering the reaction pathway of reactive intermediates are of significant importance in diversifying organic synthesis. Enol silyl ethers, versatile enolate equivalents, are known to undergo one-electron oxidation to generate the radical cations that spontaneously form electrophilic α-carbonyl radicals via elimination of the silyl groups. Here, we demonstrate that close scrutiny of the property of the radical cations as strong C–H acids enables the identification of a catalyst system consisting of an iridium-based photosensitizer and 2,4,6-collidine for the generation of nucleophilic allylic radicals from enol silyl ethers through one-electron oxidation-deprotonation sequence under light irradiation without the desilylation of the radical cation intermediates. The resultant allylic radicals engage in the addition to electron-deficient olefins, establishing the selective allylic C-H alkylation of enol silyl ethers. This strategy is broadly applicable, and the alkylated enol silyl ethers can be transformed into highly functionalized carbonyl compounds by exploiting their common polar reactivity., Allylic C–H activation of enol silyl ethers via one-electron oxidation is usually accompanied by undesired desilylation. Here, under hybrid photoredox and Brønsted base catalysis, the authors show the mild functionalization of enol silyl ethers, providing a platform to access an array of complex carbonyl compounds.

The synergy of an Ir-based photosensitizer with mild oxidizing ability and a thiol catalyst enables efficient allylic C–H functionalization of enol silyl ethers with imines under visible light irradiation. Subsequent transformations of the aminoalkylated enol silyl ethers allow for the facile construction of unique molecular frameworks such as functionalized octahydroisoindol-4-one.

The complex of chiral C2-symmetric bis-1,2,3-triazole and an achiral Bronsted acid is introduced as a new class of chiral acid catalysts. The catalytic activity and stereocontrolling ability of this chiral Bronsted acid can be tuned simply by changing the achiral acid. The synthetic relevance of this salient feature is demonstrated in the asymmetric Friedel–Crafts reaction of indoles with N-sulfonyl imines.

In this paper, a newly developed ultra-high resolution tactile sensor with a spatial resolution of 0.1µm and a force resolution of 60µN is reported for the first time. The ultrahigh resolution tactile sensor is required for quality control of finished metal surface and painted surface of automobiles that are not replaced by “non-contact” optical measurements. A 0.1µm spatial resolution is realized by a needle-like contactor-tip precisely formed by deep-RIE. A 60µN force resolution is realized by partly narrowed silicon spring. Also, piezoresistors were arranged to maximize the stress sensitivity considering the crystal orientation dependency on piezoresistive effect. The fabricated new device in this study has realized 6 times higher performance in vertical displacement and 40 times higher performance in frictional force resolution than the tactile sensor device that we reported in 2018 [1]. Measured surface shape corresponded well to the actual surface shape in deep sub-micron region.

Summary Direct catalytic methods for the stereoselective introduction of various non-protected amines at the carbon atom adjacent to a carbonyl group remain elusive in synthetic chemistry, even though they offer the most straightforward entry to chiral α-aminocarbonyl compounds. Here, we demonstrate that the in situ activation of hydroxylamines with trichloroacetonitrile enables direct transfer of their amine moieties to the C-3 position of oxindoles with rigorous enantiocontrol under the catalysis of chiral 1,2,3-triazolium salts. This protocol provides a powerful and practical means of accessing optically active 3-aminooxindoles with a wide array of alkyl and aryl substituents on nitrogen. Other carbonyl compounds, such as β-ketoesters and α-cyanoesters, can also be directly transformed into the corresponding α-aminocarbonyls with high enantioselectivity.

This is the first report about “sense of touch in submicron region” realized by novel 2-axis tactile sensor with a needle-like contactor. Simultaneous detection of submicron surface shape and correlated minute frictional force is realized by 0.5μm-radius contactor tip and highly sensitive strain sensing part of the sensor. Furthermore, contacting the contactor tip to measuring sample surface at a 10° slant angle, one-point contact is realized, and the spatial resolution of tactile sensing has been drastically improved to submicron range.

In this study, we have aimed to improve the light extraction efficiency by using p- and n- high-reflectivity indium tin oxide (ITO)/Al electrodes with a reflectivity of ∼77% at 350 nm, laser lift-off (LLO) method, and silicone sealing. By a combination of these three methods, the light output power and operating voltage of UV LEDs were improved to 23.8 mW and 6.6 V at 100 mA. Furthermore, the external quantum efficiency and light extraction efficiency were improved to 6.6 and 25.3% at 100 mA. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We have investigated novel reflective electrodes by combining an indium–tin oxide (ITO) layer and a SiO2/AlN dielectric multilayer (DM) for UV-light-emitting diodes (LEDs). The reflectance of 10 pairs of SiO2/AlN DM reached 98.5% at 350 nm. As a result, the ITO/DM electrodes simultaneously satisfied the requirements of high reflectivity in the UV region, good contact characteristics, and current spreading. The light output power of the UV LED with an ITO/DM electrode is 1.2 and 1.6 times higher than those of LEDs with ITO/Al and Ni/Au electrodes, respectively.