In recent years, food demand has been growing due to the expansion of global population and the economic development of emerging countries. Considering limited land resource, agrochemicals are indispensable for stable food production. In Japan, agrochemicals have become even more valuable as a labor-saving tool because Japan suffers from low self-sufficiency of the food and decreasing agricultural population.

Under these circumstances, global agrochemical sales have doubled and reached approximately $60 billion in the last ten years. Regardless of the large market value, agrochemical research and development (R&D) process is rarely reported, while pharmaceutical counterpart is well known. Although agrochemical and pharmaceutical R&D processes share a lot in common, some challenges are characteristic to agrochemical discovery. In this article, I will outline the agrochemical R&D process and give insights into a role of organic synthesis in agrochemical discovery.

Conducting charge-transfer complexes and salts have attracted much attention of organic chemists, physicists and materials scientists for 60 years, and is an active research area in the development of functional organic materials. We have been studying the hydrogen-bonded charge-transfer complexes where the cooperation of hydrogen-bond and charge-transfer interactions causes new functions and phenomena induced by the well-defined self-assembled networks and cooperative proton-electron transfer. This review deals with our recent studies on the designs and syntheses of hydrogen-bonded charge-transfer complexes based on the tetrathiafulvalene derivatives with hydrogen-bonding functional groups (nucleobases and imidazoles) and tetracyanoquinodimethane radical anion salts with protonated oligo (imidazole) cations. The investigations revealed that the self-assembling ability by hydrogen-bonds constructs various supramolecular architectures involving the conduction columns and further that the donor-acceptor hydrogen-bonds modulates the electronic structure producing highly conductive charge-transfer complexes.

Transition metal-catalyzed C-H activation/functionalization reactions are attractive and promising methods in modern organic synthesis. Trivalent rhodium with a pentamethylcyclopentadienyl ligand, Cp^*Rh^III, is one of the most successful catalysts for directing group-assisted C-H functionalization reactions, exhibiting high reactivity, robustness, and good functional group compatibility. Cobalt is analogous to rhodium in the periodic table, but less expensive and more available than rhodium. In this article, we describe our studies on Cp^*Co^III-catalyzed directing group-assisted C-H functionalization reactions. The cobalt catalysts not only enable the same transformations as the rhodium catalysts, but also exhibit unique reactivity and selectivity in several reactions due to the lower electronegativity, smaller size, and harder nature of cobalt compared with those of rhodium.

Catalytic asymmetric C-H functionalization using Cp^*M^III (M=Co, Rh, Ir) catalysts is highly challenging because additional chiral ligands cannot participate in an enantio-determining step. Although well-designed chiral Cp^x ligands were developed and used for catalytic asymmetric reactions, the synthesis of such chiral Cp^x ligands and complexes is sometimes an obstacle to tuning the catalyst structure for achieving high enantioselectivity. As a different approach for asymmetric reactions, we demonstrated that chiral sulfonates and chiral carboxylic acids hybridized with achiral rhodium and cobalt complexes enable enantioselective C-H functionalization.

Since a cyano group can be transformed to carboxylic acids, amino- and hydroxymethyl groups as well as aldehydes, its installation, particularly catalytic protocol, has been one of the challenging issues in synthetic chemistry. Hydrocyanation of non-activated C-C multiple bonds has been one of the most powerful methods to install a CN group although selectivity control in products has been major challenge because simple olefin such as styrene derivatives is the only substrate to give higher regioselectivity in HCN addition process. In this review, the authors summarize.

Palladium-catalyzed reactions via π-allylpalladium intermediates are one of the most powerful methods for the synthesis of various compounds. Among such reactions, the cross-coupling reaction of propargylic carbonates with substrates having two nucleophilic sites is one of the effective synthetic methods for various cyclic compounds. In spite of its success in organic synthesis, the palladium-catalyzed cross-coupling polymerization using propargylic carbonates had not been investigated. Propargylic carbonates undergo two consecutive reactions with nucleophiles under palladium catalysis. Therefore, we have focused on the propargylic carbonates as monomers for the palladium-catalyzed cross-coupling polymerization. In this review, we describe a comprehensible overview of our recent studies using propargylic carbonates. The polymerizations of propargylic carbonates with bifunctional nucleophiles afforded various polymers with exomethylene groups in the main chains. In addition, cross-conjugated polymers composed of 2,3-butadiene and arenes were successfully synthesized by palladium-catalyzed cross-coupling polymerization of bis(propargylic carbonate)s with aromatic diboronic acids. Furthermore, such interesting exomethylene structure is suitable for post-functionalization and-transformation. The 2,3-butadiene structure of cross-conjugated polymers could easily be converted into vinylene structure of linear-conjugated polymers through Diels-Alder reaction.

Oligosaccharides, are linked to biomolecules (i.e. proteins and lipids) by glycosidic bonds, display on the surface of cells and play important roles in a wide range of biological events. Recent remarkable advances in carbohydrate chemistry can provide structurally well-defined oligosaccharides, which lead to molecular-level elucidation of their functions. In conventional approaches for oligosaccharide synthesis, to glycosylate at a given carbohydrate hydroxyl group, other hydroxyl groups must be masked with protecting groups. Recently, however, “protecting-group-free” synthetic approaches, are challenging and promising, have been reported by several research groups. This present review describes recent developments of stereoselective glycosylations using unprotected glycosyl donors.

Organic compounds, mostly transparent in the visible area, are not necessarily transparent when they form electron-donor-acceptor (EDA) complexes. Once irradiated with visible light, EDA complexes can undergo photo-induced electron transfer (PET) between each component to generate a pair of radical species. Because of today's widespread recognition on the power of visible light for organic synthesis, we are experiencing unprecedented revisit to this phenomenon. This article overviews the history and synthetic application of PET between both ordinary organic compounds.

Pyridoxal phosphate (PLP) activates amino group to promote various types of biochemical transformations. This review focused on the enantioselective reactions of amino acid derivatives enabled by chiral carbonyl catalysis mimicking PLP.