The acid-base combination chemistry is one of the most reliable concepts for designing high performance catalysts. Acid-base combined catalysts can be classified into two types, ion pair catalysts (type A) and acid-base cooperative catalysts (type B). Type A can be subclassified into acidic/basic/neutral salt catalysts (types A1/A2/A3). Type B can be subclassified into conjugationally noninteractive/interactive acid-base catalysts (types B1/B2). Tailor-made multi-selective catalysts can also be designed based on the acid-base combination chemistry. Our recent progress has been described here.

Current technologies of DCP-RIM (reaction injection molding of dicyclopentadiene) are reviewed from an industrial point of view. The DCP-RIM provides high-impact, heat resistant, and insulating poly(dicyclopentadiene) thermoset resin via catalytic olefin metathesis. Control of chemical reactivities of the catalysts is one of the most important technologies for the DCP-RIM. The key properties of the catalysts are their good solubility in dicyclopentadiene and latency.

Suitable tungsten or molybdenum-based catalyst systems have been developed and used for over 30 years. These catalyst systems are comprised of inorganic tungsten (or molybdenum) salt and an air-sensitive organoaluminum as an activator. In contrast, robust Grubbs type ruthenium-alkylidene catalysts are attracted great interest in the field of the DCP-RIM. Detailed structure and reactivities of the ruthenium catalysts for the DCP-RIM are summarized.

(2-Deoxy-2-fluoro-4-thio-β-d-arabinofuranosyl)thymine (S-FMAU) was synthesized very efficiently from corresponding d-arabinofuranose derivative 16a which was available in bulk. Three important transforming methods were mainly described. One was the practical inversional bromination process for secondary alcohol generated by opening furanose ring. Another was the highly efficient thiofuranose synthesis via intramolecular carbonyl assisted S_N2 reaction. And the last was the β-selective glycosylation process with thymine derivative. Applications of the thiofuranose synthesis using intramolecular carbonyl assist were also discussed.

Hypervalent iodine reagents have been recognized as useful and environmentally benign reagents, and widely used in organic synthesis. Among them, (difluoroiodo)arenes and Togni’s reagents are stable, low toxic, and have attracted much attention as useful fluorinating reagents because they can reduce the drawbacks found in direct fluorination reactions with fluorine gas. However, most (difluoroiodo)arenes are prepared by reaction of iodosylarenes with HF reagents. For the fluorination reaction, in addition, (difluoroiodo)arenes must be activated by a HF reagent such as HF·amine complexes. Accordingly, HF is essential both for the preparation and for the activation of ArIF₂ in the fluorination reaction. To avoid such tedious procedures and develop a convenient method, we envisaged one-pot fluorination reactions achieving both preparation of a(difluoroiodo)arene and its activation for fluorination. In the fluorination reaction, HF is considered to play two roles as the reagent for the generation of ArIF₂ and as the activating agent for the fluorination reaction. Using a convenient fluorinating reagent composed of a hypervalent iodine compound and a HF source, we conducted the following reactions: (1) selective fluorination of carbonyl compounds such as 1,3-diketones, β-ketoesters, β-ketoamides, malonic esters and aromatic ketones, and (2) gem-difluorination of styrenes. The detailed results are reported.

The use of photoreactions such as photoredox catalysts in asymmetric synthesis has been expansively recognized as expedient procedure over the past decade. In this paper, a potential application of photoreaction of Charge-Transfer (CT) complex for asymmetric synthesis is described. In chiral donor-acceptor systems, excitation wavelength, along with other environmental factors such as solvent polarity and temperature, plays more substantial role in determining the stereoselectivity of the photochemical outcomes. Accordingly, the excited CT complex produced upon the selective CT-band excitation behaves completely different from the conventional exciplex, which is formed by the direct excitation of donor or acceptor. Such unique wavelength effect, together with other entropic controls, may possibly come to be valuable means in asymmetric photochemical synthesis for the future.

Asymmetric conjugate addition reaction to β,β-disubstituted enones is one of reliable and straightforward approaches to afford ketones carrying all-carbon substituted quaternary carbon center at the β-position. Although metal-catalyzed conjugate addition reaction of organometallic nucleophiles has been developed, less is known about organocatalyzed asymmetric conjugate addition reaction to β,β-disubstituted enones. This review focuses on recent reports about organocatalyzed nitro-Michael addition and alkyl radical addition reaction to β-substituted cyclic enones.

Hexaarylbenzenes (HABs) have been attracting a great deal of research interest derived from their propeller-shaped geometry. Well-designed multi-substituted HABs have unique utilities, such as organic electronics and scaffolds for supramolecular assembly. However synthetic methods for multi-substituted HABs are limited. In this mini review, I describe recent advances in rational synthesis of HAB with 5 or 6 different aryl groups.