Process studies of E2212 (1) toward rapid clinical introduction are described. Through comprehensive route finding studies and optimization of key condensation and cyclization steps, a racemate-based manufacturing route could be established and successfully scaled-up to hundred kilogram scale. For a rapid delivery of drug substance containing Z-isomer for preclinical safety studies, successful scale-up of photo-isomerization of an olefin under flow system is also presented.

Helicenes are nonplanar 3D screw-shaped polycyclic compounds based on ortho-fused benzenes or aromatic rings, unlike other chiral compounds, and exhibit unique structural, optical, and electronic features. Thus, a large number of helicenes were investigated so far for a broad range of applications in study on chirality, catalysis, optoelectronics, and biology. In this study, a variety of carbo［5］helicenes with a substituent exclusively oriented toward the interior curvature of the helix are synthesiszed by PtCl₂-catalyzed cycloisomerization. These［5］helicenes show a high enough configurationally stability. Based on this research, a series of novel optically active［5］helicene-derived phosphine ligands (L1, with a 7,8-dihydro［5］helicene core structure- and L2, with a fully aromatic［5］helicene core structure) were synthesized and applied to Pd-catalyzed asymmetric reactions. Furthermore, we recently designed and synthesized internal-edge-substituted coumarin-fused［6］helicenes with a phenyl substituent. Of particular note, the enantiomerically pure crystal adopted a one-dimensional columnar structure, which clearly showed the importance of the proper choice of a substituent for columnar arrangement.

The modern history of organic electronics based on conducting polymers started with doped polyacetylene in 1970’s. However, polyacetylene suffers many problems, such as structural disorder along C-C single bonds, the resulting short effective conjugation length, and insolubility. To address these issues, many efforts were made in terms of partial rigidification of the polyene structure with heteroatom and carbon linkages. Among them, oligo(phenylenevinylene)s (OPVs) are all-carbon analogues of polyacetylenes, albeit many C-C single bonds that can freely rotate are still left in a molecular framework. We envisioned that full linkages between each phenylene and vinylene unit using sp³-carbon atoms can rigidify the entire OPV skeleton. Indeed, methylene-bridged stilbene was prepared in 1922, and the longer homologue of such carbon-bridged oligo(phenylenevinylene)s (COPV) is a framework of which construction had been a long-term challenge in a field of synthetic organic chemistry. In 2009 we have reported the synthesis of COPV based on a novel intramolecular cyclization reaction to afford a dilithiated indacene framework, a key intermediate to construct the COPV framework. Thus prepared COPV were found to show not only excellent photophysical and electronic properties due to the rigid planar π-conjugated framework, but also high stability and solubility due to the organic side chains installed on the bridging carbon atoms that sterically protect the π-conjugated framework. With these features, the COPV molecules have also served as versatile materials at a single-molecular and a bulk level, such as in organic thin-film lasers, dye-sensitized and perovskite solar cells, and molecular wires. Remarkable discoveries in the area connecting chemistry and physics include inelastic tunneling and long-range resonance tunneling at ambient temperature, which were previously observed only for organic molecules under cryogenic conditions. This class of newly prepared molecules created by the power of organic synthesis will serve as versatile materials for fundamental and applied researches in a broad range of field.

π-Conjugated organophosphorus compounds represented by phospholes serve as unique building blocks and functional cores for various organic functional materials, due to the unique features such as σ^＊-π^＊ hyperconjugation and P-modulability. Therefore, the development of novel π-conjugated organophosphorus building blocks and core scaffolds would be of great importance to open up new horizons of phosphorus-containing functional materials. Recently, we have revisited missing pieces of organophosphorus compounds, i.e., aromatic-fused diketophosphanyl compounds, and cultivated their potential use as building blocks for functional organic materials. In this account, our contributions to the development of diketophosphanyl-cored organic materials are described.

Dynamic molecular materials have been designed by focusing on the intermolecular hydrogen-bonding interaction in molecular assemblies. For instance, one-dimensional and two-dimensional columnar amide-type hydrogen-bonding interactions of aromatic oligoamide (-CONHC_nH_2n＋1) derivatives were responsible for the external electric field in liquid crystalline state, which induced the polarization inversion and ferroelectricity. Multi-functional ferroelectric organic materials such as fluorescent - ferroelectrics and current switching - ferroelectrics were designed by choosing in a central π-electron core. Mechanically thermoresponsive crystalline materials with high thermal stability were also obtained by designing in the hydrogen-bonding array of dynamic π-molecular system. Through the precise designs of dynamics in molecular assemblies including in the functional π-electron system, “bulk dynamic” properties such as ferroelectricity and thermosalient behavior were coupled with the intrinsic π-electronic properties such as electrical conducting, magnetic, and optical properties. Such multi-functional organic materials have a potential to construct a new molecular science.

DNA encoded library (DEL) has emerged as a widely utilized chemical library, possessing DNA-tag on each compound, for discovering hit compounds in drug discovery. However, synthetic methods for DEL are not fully exploited due to the difficulty in chemical transformation of DNA encoded compounds. This mini-review focuses on the recent development on organic synthesis for diversity expansion of DEL.