The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Hitoshi Takeshita - One of the best experts on this subject based on the ideXlab platform.
-
mesomorphic properties of 2 acyloxy5 4 alkoxyphenylazo Tropones 2 acyloxy 5 4 alkylphenylazo Tropones and 2 acyloxy 5 4 alkoxycarbonylphenylazo Tropones
Liquid Crystals, 2002Co-Authors: Akira Mori, Hitoshi Takeshita, Yasuo Kakihara, Seiji UjiieAbstract:Three series of mesomorphic 2-acyloxy-5-phenylazoTropones with alkoxy, alkyl, and alkoxycarbonyl groups at C-4 on the phenyl ring were prepared. It was known that the corresponding 5-phenylazotropolone derivatives and their methyl ethers were not mesomorphic. 2-Acetyl-5-(4-hexyloxyphenylazo)tropone, however, shows a monotropic smectic A phase. Even an acetyl group is therefore able to induce a mesophase. The effects of terminal substitution of the tropone ring by groups such as alkoxy, alkoxycarbonyl, and alkyl on the clearing points are discussed.
-
new troponoid liquid crystalline compounds 5 alkoxy 2 4 alkoxybenzoylamino Tropones
Chemistry Letters, 1997Co-Authors: Akira Mori, Hitoshi Takeshita, Nobuo Kato, Ken Hirayama, Seiji UjiieAbstract:The X-ray crystallographic structural analysis of 5-butoxy-2-(4-methoxybenzoylamino)tropone, a liquid crystalline compound, revealed to form the head-to-tail dimer, in which a CH-π interaction between the benzoyl π-system and the β-hydrogen of the 5-butoxy group on the tropone ring of the neighboring molecule as well as intermolecular π-π stacking interactions with the two tropone systems. On the other hand, 2-(4-alkoxybenzoylamino)-5-methoxytropone lacking the β-hydrogen and the corresponding benzenoid, N-(4-alkoxyphenyl)-4-alkoxybenzamide were non-mesogenic.
-
mesogenic properties of tricyclic 2 5 di 4 alkoxybenzoyloxy Tropones increasing smectic thermal stabilities by the lateral polar carbonyl group
Chemistry Letters, 1996Co-Authors: Akira Mori, Hisashi Taya, Minoru Uchida, Hitoshi TakeshitaAbstract:2,5-Di(4-alkoxybenzoyloxy)Tropones showed similar mesogenic properties to the corresponding benzenoids. The tropone carbonyl group, which behaved as a polar lateral substituent, enhanced the thermal stability of the smectic phases and reduced that of the nematic phases when compared with those of the benzenoids. The tropone carbonyl group induced an intermolecular attractive force.
-
Intramolecular rearrangement of 2-(2-propynylsulfinyl)tropone and its homologues to cyclohepta [b]thiophen-8-ones
Heterocycles, 1991Co-Authors: Akira Mori, Hitoshi TakeshitaAbstract:Thermal reaction of 2-(2-alkynylsulfinyl) Tropones afforded 3-acylcyclohepta [b] thiophen-8-ones, their dihydro derivatives as well as deacylated 2,3-dihydroxyclohepta [b] thiophen-8-ones. Deuterium labelling experiment confirmed the intramolecular reaction mode, which is different from the mechanism reported for the reaction of 2-(2-propenylsulfinyl) Tropones
-
neighboring effect of a carbonyl group in base induced wittig type rearrangements of poly 4 nitrobenzyloxy Tropones to bis and mono α hydroxy 4 nitrobenzyl Tropones
Bulletin of the Chemical Society of Japan, 1991Co-Authors: Akira Mori, Hitoshi TakeshitaAbstract:The base-catalyzed rearrangement of bis- and tris(4-nitrobenzyloxy)Tropones gave (α-hydroxy-4-nitrobenzyl)Tropones through a Wittig-type mechanism. Only the 4-nitrobenzyloxy group adjacent to the carbonyl group migrated. The carbonyl group played a role in facilitating the rearrangement by chelation with the sodium on the adjacent carbanion.
Akira Mori - One of the best experts on this subject based on the ideXlab platform.
-
mesomorphic properties of 2 acyloxy5 4 alkoxyphenylazo Tropones 2 acyloxy 5 4 alkylphenylazo Tropones and 2 acyloxy 5 4 alkoxycarbonylphenylazo Tropones
Liquid Crystals, 2002Co-Authors: Akira Mori, Hitoshi Takeshita, Yasuo Kakihara, Seiji UjiieAbstract:Three series of mesomorphic 2-acyloxy-5-phenylazoTropones with alkoxy, alkyl, and alkoxycarbonyl groups at C-4 on the phenyl ring were prepared. It was known that the corresponding 5-phenylazotropolone derivatives and their methyl ethers were not mesomorphic. 2-Acetyl-5-(4-hexyloxyphenylazo)tropone, however, shows a monotropic smectic A phase. Even an acetyl group is therefore able to induce a mesophase. The effects of terminal substitution of the tropone ring by groups such as alkoxy, alkoxycarbonyl, and alkyl on the clearing points are discussed.
-
Directional Effects of the Carbonyl Group on the Mesogenic Properties of Twin Troponoids
Molecular Crystals and Liquid Crystals, 2001Co-Authors: Akira Mori, Manabu Takemoto, Volkmar Vill, Seiji UjiieAbstract:Abstract Transition temperatures of four twin types of troponoid liquid crystals, in which the direction of the tropone carbonyl groups and a kind of the spacer were different from each other, were discussed. Symmetrical twin dimers 1, in which two tropone carbonyl groups direct inside, had monotropic smectic C phases whereas another symmetrical twin dimers 3 were less mesogenic than 1. Unsymmetrical twin dimers 4 had smectic A phases. Compared their thermal stabilities, unsymmetrical 4 had the highest clearing point when the number of atoms of the inner spacer was identical.
-
3-Phenylpyrrolo[2,3-b]tropone
Acta Crystallographica Section E-structure Reports Online, 2001Co-Authors: Kanji Kubo, Teppei Tsujimoto, Akira MoriAbstract:The title compound, C15H11NO, exists in the crystal in its keto form as 3-phenylpyrrolo[2,3-b]tropone [systematic name: 3-phenylcyclohepta[b]pyrrol-8(1H)-one] rather than in the enol form as 8-hydroxy-3-phenyl-1-azaazulene. The seven-membered ring shows pronounced bond alternation typical of tropone derivatives.
-
new troponoid liquid crystalline compounds 5 alkoxy 2 4 alkoxybenzoylamino Tropones
Chemistry Letters, 1997Co-Authors: Akira Mori, Hitoshi Takeshita, Nobuo Kato, Ken Hirayama, Seiji UjiieAbstract:The X-ray crystallographic structural analysis of 5-butoxy-2-(4-methoxybenzoylamino)tropone, a liquid crystalline compound, revealed to form the head-to-tail dimer, in which a CH-π interaction between the benzoyl π-system and the β-hydrogen of the 5-butoxy group on the tropone ring of the neighboring molecule as well as intermolecular π-π stacking interactions with the two tropone systems. On the other hand, 2-(4-alkoxybenzoylamino)-5-methoxytropone lacking the β-hydrogen and the corresponding benzenoid, N-(4-alkoxyphenyl)-4-alkoxybenzamide were non-mesogenic.
-
mesogenic properties of tricyclic 2 5 di 4 alkoxybenzoyloxy Tropones increasing smectic thermal stabilities by the lateral polar carbonyl group
Chemistry Letters, 1996Co-Authors: Akira Mori, Hisashi Taya, Minoru Uchida, Hitoshi TakeshitaAbstract:2,5-Di(4-alkoxybenzoyloxy)Tropones showed similar mesogenic properties to the corresponding benzenoids. The tropone carbonyl group, which behaved as a polar lateral substituent, enhanced the thermal stability of the smectic phases and reduced that of the nematic phases when compared with those of the benzenoids. The tropone carbonyl group induced an intermolecular attractive force.
Hisashi Yamamoto - One of the best experts on this subject based on the ideXlab platform.
-
lewis acid catalyzed inverse electron demand diels alder reaction of Tropones
Journal of the American Chemical Society, 2009Co-Authors: Pingfan Li, Hisashi YamamotoAbstract:Lewis acid catalyzed inverse-electron-demand Diels−Alder reaction of tropone derivatives was developed. Up to 97% ee was obtained for the chiral dinucleus BINOL−aluminum complex catalyzed reaction between Tropones and ketene diethyl acetal to give bicyclo[3.2.2] ring structures, which opens up a unique way of making chiral seven-membered rings.
-
Lewis Acid Catalyzed Inverse-Electron-Demand Diels−Alder Reaction of Tropones
Journal of the American Chemical Society, 2009Co-Authors: Pingfan Li, Hisashi YamamotoAbstract:Lewis acid catalyzed inverse-electron-demand Diels−Alder reaction of tropone derivatives was developed. Up to 97% ee was obtained for the chiral dinucleus BINOL−aluminum complex catalyzed reaction between Tropones and ketene diethyl acetal to give bicyclo[3.2.2] ring structures, which opens up a unique way of making chiral seven-membered rings.
Pingfan Li - One of the best experts on this subject based on the ideXlab platform.
-
lewis acid catalyzed inverse electron demand diels alder reaction of Tropones
Journal of the American Chemical Society, 2009Co-Authors: Pingfan Li, Hisashi YamamotoAbstract:Lewis acid catalyzed inverse-electron-demand Diels−Alder reaction of tropone derivatives was developed. Up to 97% ee was obtained for the chiral dinucleus BINOL−aluminum complex catalyzed reaction between Tropones and ketene diethyl acetal to give bicyclo[3.2.2] ring structures, which opens up a unique way of making chiral seven-membered rings.
-
Lewis Acid Catalyzed Inverse-Electron-Demand Diels−Alder Reaction of Tropones
Journal of the American Chemical Society, 2009Co-Authors: Pingfan Li, Hisashi YamamotoAbstract:Lewis acid catalyzed inverse-electron-demand Diels−Alder reaction of tropone derivatives was developed. Up to 97% ee was obtained for the chiral dinucleus BINOL−aluminum complex catalyzed reaction between Tropones and ketene diethyl acetal to give bicyclo[3.2.2] ring structures, which opens up a unique way of making chiral seven-membered rings.
Akkattu T Biju - One of the best experts on this subject based on the ideXlab platform.
-
diels alder reaction of Tropones with arynes synthesis of functionalized benzobicyclo 3 2 2 nonatrienones
ChemInform, 2014Co-Authors: Manikandan Thangaraj, Sachin Suresh Bhojgude, Rajesh Bisht, Rajesh G Gonnade, Akkattu T BijuAbstract:A new procedure for the mild, practical, and scalable Diels—Alder reaction of Tropones with arynes is reported.
-
Diels—Alder Reaction of Tropones with Arynes: Synthesis of Functionalized Benzobicyclo[3.2.2]nonatrienones.
ChemInform, 2014Co-Authors: Manikandan Thangaraj, Sachin Suresh Bhojgude, Rajesh Bisht, Rajesh G Gonnade, Akkattu T BijuAbstract:A new procedure for the mild, practical, and scalable Diels—Alder reaction of Tropones with arynes is reported.
-
diels alder reaction of Tropones with arynes synthesis of functionalized benzobicyclo 3 2 2 nonatrienones
Journal of Organic Chemistry, 2014Co-Authors: Manikandan Thangaraj, Sachin Suresh Bhojgude, Rajesh Bisht, Rajesh G Gonnade, Akkattu T BijuAbstract:A new procedure for the mild, practical, and scalable Diels–Alder reaction of Tropones with arynes is reported. Differently substituted Tropones undergo selective [4 + 2] cycloaddition with arynes generated in situ by the fluoride-induced 1,2-elimination of 2-(trimethylsilyl)aryl triflates, allowing the formation of functionalized benzobicyclo[3.2.2]nonatrienone derivatives in moderate to good yields. In addition, the photophysical properties of the cycloadducts are presented.