Mitsunori Takeda

A highly stereocontrolled synthesis of α-hydroxycyclopropanes possessing a trifluoromethyl group

Abstract The preparation of optically pure syn and anti-α-hydroxycyclopropanes possessing a trifluoromethyl group from stereoisomers of optically pure allylic alcohols by samarium-based carbenoids is described.

Synthetic approach to stereoisomers of allylic alcohols possessing a trifluoromethyl group

Abstract A number of stereoisomers of optically pure allylic alcohols with a trifluoromethyl group [CF3CH(OH)CH=CHR : R=Ph. C6H13] were prepared, utilizing the enantiotopic specificity of asymmetric hydrolysis of their acetates by hydrolases. Their absolute configurations were determined.

Trifluoromethylated pyranose derivatives as the chiral dopant for ferroelectric liquid crystals

Abstract The novel pyranose derivatives with a trifluoromethyl group were found to be excellent chiral dopants for ferroelectric liquid crystals, inducing large spontaneous polarization by their addition even in a small quantity. These materials showed some characteristic physical properties depending on their stereochemical relationship : thus, the corresponding cis isomers exhibited high ability in inducing large spontaneous polarization and quick response but lowered the upper limit of the temperature of the Sc phase. However, the same trend in the spontaneous polarization was observed for the compounds with trans stereochemistry, without lowering the transition temperature of SA to SC, of the host liquid crystal. MoFover, it was also proved that the adjustment of the helical pitch of the N* phase was readily carried out. Based on these results, we have succeeded in the development of the practical ferroelectric liquid crystalline compositions with good alignment and quick response.

Synthesis of optically active γ-lactones and dopants for ferroelectric liquid crystals possessing a trifluoromethyl group

Abstract A series of trans- and cis-γ-lactones with high optical purity have been prepared from the lactonization of (S)-(−)-2-(trifluoromethyl)-4-pentenoic acid (>94% ee) under acidic conditions. These materials have been transformed into new types of dopant for ferroelectric liquid crystals possessing a trifluoromethyl group.

Ferroelectric Liquid Crystal Mixtures Containing Chiral Pyranose Compounds for Response-Voltage Minimum Mode

Ferroelectric liquid crystal (FLC) materials for the response-voltage minimum (τ–Vmin ) mode were developed by doping novel chiral pyranose compounds into achiral host materials with negative dielectric anisotropy. The chiral pyranose derivatives, wherein three chiral centers and a trifluoromethyl group were fixed in the 6-membered ring, induced short τmin in the τ–Vmin characteristic. The developed FLC materials were driven by drive schemes for the τ–Vmin mode, giving short line address times.

Synthesis and properties of trifluoromethylated chiral dopants for ferroelectric liquid crystals

The synthesis and specific properties of a new family of chiral dopants for ferroelectric liquid crystals, which are derived from a series of trifluorinated dihydrofuranones and tetrahydrofurans, are described. On the basis of the structural features of designed materials and the MOPAC-PM 3 calculations, a discussion of the response time-structure relationships is given. Optically active trifluoromethylated materials with a tetrahydrofuran tail unit were found to be superior chiral dopants for preparing ferroelectric liquid crystalline compositions.

ENZYMATIC RESOLUTION IN ORGANIC MEDIA : SYNTHESIS OF OPTICALLY ACTIVE FURANOLS POSSESSING A FLUOROALKYL GROUP

Abstract Furanols possessing a fluoroalkyl group were resolved into the corresponding optically active forms via enzymatic esterification in organic media.

Stereoselective synthesis of chiral 2,3-epoxycompounds possessing fluorinated methyl groups

Abstract The preparation of fluoromethylated optically pure trans epoxycompounds , C (OH)Me2] from the corresponding β - hydroxyketones and/or esters is described.

A low waste route to large scale enzymatic resolution

A new large scale route to enzymatic resolution of a chiral dopant of ferroelectric liquid crystals, in the absence of any organic medium or water, is described. After removal of the catalyst in this low waste process, no further operation is required before the direct distillation.

Novel Antiferroelectric Liquid Crystals Derived from Trifluoromethylated Pyranoses

Abstract A new series of liquid crystals possessing trifluoromethylated pyranoses was synthesized and their mesomorphic properties were investigated. Electro-optical studies showed that some of these compounds exhibited an antiferroelectric chiral smectic C (SmCA*) phase. Further, it was found that the appearance of the SmCA* phase was strongly dependent on the conformation of the chiral part; cisand transconfigurations of the pyranose ring. Relationship between molecular structures and a propensity to the formation of the SmCA* phase was discussed.