Shinichi Koguchi

A concise approach to homochiral 3,4-dihydroxyglutamic acids

Abstract A concise diastereoselective synthesis of 3,4-dihydroxyglutamic acids was investigated. The key reaction in this synthesis is stereoselective cyanation of an optically active N -acyliminium intermediate derived from l - or d -tartaric acid. The stereoselectivity in the cyanation reaction could be controlled by the protective group of the hydroxyl function. Deprotection of the obtained cyanolactam followed by acidic hydrolysis afforded the desired 3,4-dihydroxyglutamic acids. The 3,4-dihydroxyglutamic acids obtained in this synthesis are (2 S ,3 S ,4 R )-, (2 R ,3 S ,4 R )-, (2 S ,3 R ,4 S )-, and (2 R ,3 R ,4 S )-isomers and the three latter compounds are novel derivatives of glutamic acids.

Ionic Liquid-Phase Synthesis of 1,5-Disubstituted 1,2,3-Triazoles

A simplified ionic liquid-phase synthesis of 1,5-disubstituted 1,2,3-triazole was developed. Nineteen 1,5-disubstituted 1,2,3-triazoles were successfully obtained by merely washing the ionic liquid phase with ether, thus avoiding the need for intermediate purification.

A concise diastereoselective synthesis of (2S,3S,4R)-3,4-dihydroxyglutamic acid

Abstract A concise diastereoselective synthesis of (2S,3S,4R)-3,4-dihydroxyglutamic acid, one of eight possible stereoisomers of 3,4-dihydroxyglutamic acids, is described. The key reaction in this synthesis is stereoselective cyanation of an optically active N-acyliminium intermediate derived from l -tartaric acid with tributyltin cyanide.

Conductive Hybrid Crystal Composed from Polyoxomolybdate and Deprotonatable Ionic-Liquid Surfactant

A polyoxomolybdate inorganic-organic hybrid crystal was synthesized with deprotonatable ionic-liquid surfactant. 1-dodecylimidazolium cation was employed for its synthesis. The hybrid crystal contained δ-type octamolybdate (Mo8) isomer, and possessed alternate stacking of Mo8 monolayers and interdigitated surfactant bilayers. The crystal structure was compared with polyoxomolybdate hybrid crystals comprising 1-dodecyl-3-methylimidazolium surfactant, which preferred β-type Mo8 isomer. The less bulky hydrophilic moiety of the 1-dodecylimidazolium interacted with the δ-Mo8 anion by N–H···O hydrogen bonds, which presumably induced the formation of the δ-Mo8 anion. Anhydrous conductivity of the hybrid crystal was estimated to be 5.5 × 10−6 S·cm−1 at 443 K by alternating current (AC) impedance spectroscopy.

Polymerizable Ionic Liquid Crystals Comprising Polyoxometalate Clusters toward Inorganic-Organic Hybrid Solid Electrolytes

Solid electrolytes are crucial materials for lithium-ion or fuel-cell battery technology due to their structural stability and easiness for handling. Emergence of high conductivity in solid electrolytes requires precise control of the composition and structure. A promising strategy toward highly-conductive solid electrolytes is employing a thermally-stable inorganic component and a structurally-flexible organic moiety to construct inorganic-organic hybrid materials. Ionic liquids as the organic component will be advantageous for the emergence of high conductivity, and polyoxometalate, such as heteropolyacids, are well-known as inorganic proton conductors. Here, newly-designed ionic liquid imidazolium cations, having a polymerizable methacryl group (denoted as MAImC1), were successfully hybridized with heteropolyanions of [PW12O40]3− (PW12) to form inorganic-organic hybrid monomers of MAImC1-PW12. The synthetic procedure of MAImC1-PW12 was a simple ion-exchange reaction, being generally applicable to several polyoxometalates, in principle. MAImC1-PW12 was obtained as single crystals, and its molecular and crystal structures were clearly revealed. Additionally, the hybrid monomer of MAImC1-PW12 was polymerized by a radical polymerization using AIBN as an initiator. Some of the resulting inorganic-organic hybrid polymers exhibited conductivity of 10−4 S·cm−1 order under humidified conditions at 313 K.