New indoline dyes (RK‐1–4) were designed with a planar geometry and high molar extinction coefficient, which provided surprising power conversion efficiency (PCE) with a thin titanium dioxide film in dye‐sensitized solar cells (DSCs). They had a difference in only alkyl chain length. Despite the same molecular structure, the performance of the respective DSCs varied significantly. Investigating the dye adsorption processes and charge transfer kinetics, the alkyl chain length was determined to affect the dye surface coverage as well as the recombination between the injected photoelectrons and the oxidized redox mediators. When applied to the DSCs as a light harvester, RK‐3 with the dodecyl group exhibited the best photocurrent density, consequently achieving the best PCE of 9.1% with a 1.8 μm active and 2.5 μm scattering layer because of the most favorable charge injection. However, when increasing the active layer thickness, overall device performance deteriorated and the charge collection and regeneration played major roles for determining the PCE. Therefore, RK‐2 featuring the highest surface coverage and moderate alkyl chain length obtained the highest PCEs of 8.8% and 7.9% with 3.5 and 5.1 μm active layers, respectively. These results present a promising perspective of organic dye design for thin film DSCs.

A novel, catalytic enantioselective route to synthesize a variety of α-tertiary aryl ketones via a boron Lewis acid promoted formal insertion of aryldiazoalkane into the C-H bond of both aromatic and aliphatic aldehydes is described. In the presence of chiral (S)-oxazaborolidinium ion catalyst 1, the reaction proceeded in good yields (up to 94%) with excellent enantioselectivities (up to 99% ee).

The planarity of an organic sensitizer is one of the most crucial factors for determining molar absorptivity and intramolecular charge transfer (ICT). The photovoltaic performance of dye-sensitized solar cells dramatically changed depending on the planarity of the donor, although all dyes exhibited similar extinction coefficients, electrochemical characteristics, as well as the amount of loaded dye. The power conversion efficiency (PCE) of planar donor dyes was 3 times greater than that of twisted donor dyes because of more rapid ICT. In addition, RK-3 dye, characterized by additional donor groups on an indoline unit, exhibited broad light-harvesting ability with higher performance as compared to those observed for planar dyes with a single donor attached to the thin-film photoanode (1.8 μm transparent + 2.5 μm scattering film). The champion cell of RK-3 exhibited a PCE of 10.3% when the thickness of the active film increased to 3.5 μm, as well as when an antireflection layer was applied with an iodine-based electrolyte.

Highly enantioselective Darzens-type epoxidation of diazoesters with glyoxal derivatives was accomplished using a chiral boron-Lewis acid catalyst, which facilitated asymmetric synthesis of trisubstituted a,b-epoxy esters. In the presence of a chiral oxazaborolidinium ion catalyst, the reaction proceeded in high yield (up to 99 %) with excellent enantio-and diastereoselectivity (up to > 99 % ee and > 20:1 dr, respectively). The synthetic potential of this method was illustrated by conversion of the products to various compounds such as epoxy g-butyrolactone, tertiary b-hydroxy ketone and epoxy diester.Scheme 1. Enantioselective synthesis of epoxide with diazo compounds.

In this chapter, recent developments with regard to catalytic enantioselective reactions of furans, derived from biomass such as unsubstituted furan, 2-methylfuran, 2,5-dimethylfuran, and furfural are described. Although several review articles have dealt with the Diels-Alder reactions of furans, there have been no articles highlighting enantioselective versions. The resulting products derived from the catalytic enantioselective reaction of furan are often found as core structures in natural products and pharmaceuticals with important pharmacological activities. After recognizing the valuable skeleton of chiral furan derivatives, numerous attempts have been made to synthesize them by utilizing enantioselective cycloaddition reactions, Friedel-Crafts reactions, and nucleophilic addition reactions. Enantioselective cyclization reactions using furans as the 4π diene component provided chiral dihydrofuran derivatives. On the other hand, Friedel-Crafts and nucleophilic addition reactions served various furan derivatives with a chiral carbon atom in the α-position.