78513-04-9Relevant academic research and scientific papers
Total Synthesis of the Echinodermatous Ganglioside LLG-3 Possessing the Biological Function of Promoting the Neurite Outgrowth
Huang, Yuahn-Sieh,Shih, Jing-Feng,Tsai, Yow-Fu,Wu, Yu-Fa
, p. 7491 - 7495 (2020/10/09)
A total synthesis of echinodermatous ganglioside LLG-3 with neuritogenic activity was accomplished by a convergent strategy. The synthesis of 2-hydroxyethyl 8-O-Me-α-sialoside 2 was started from the phenyl 7,8-di-O-Pico-thiosialoside 5, which can be chemoselectively removed the picoloyl group, and then the methyl group in 8-O-MeNeu5Ac moiety was chemoselectively prepared using TMSCHN2/FeCl3. For preparation of the terminal disialic unit, oxidative amidation was initially utilized by our group to efficiently construct the α(2,11) linkage of 8-O-Me-Neu5Acα(2,11)Neu5Gc. Herein, we also demonstrate that the synthesized ganglioside LLG-3 exhibited the neuritogenic activity toward the primary cortical neurons and that biological activity is superior to that of ganglioside DSG-A.
Formal synthesis of (+)-isolaurepinnacin
Suzuki, Toshio,Matsumura, Ryuji,Oku, Ken-ichi,Taguchi, Keiichi,Hagiwara, Hisahiro,Hoshi, Takashi,Ando, Masayoshi
, p. 65 - 67 (2007/10/03)
The stereoselective formal synthesis of (+)-isolaurepinnacin is described. The required key oxepene skeleton possessing cis-oriented alkyl substituents at the α,ω-positions was stereoselectively constructed via the cyclization of the corresponding hydroxy epoxide promoted by the (Bu3Sn)2O/Zn(OTf)2 system.
Synthesis of efficient chiral bisphosphine ligands, modified DIOPs, (4R,5R)-4-(Diaryl- or dialkylphosphino)methyl-5-(diarylphosphino)methyl-2,2- dimethyl-1,3-dioxolanes, and their use in rhodium(I)-catalyzed asymmetric hydrogenations
Morimoto,Chiba,Achiwa
, p. 1149 - 1156 (2007/10/02)
Modified DIOPs, (4R,5R)-4-(diaryl- or dialkyphosphino)methyl-5- (diarylphosphino)methyl-2,2-dimethyl-1,3-dioxolanes, were prepared on the basis of our design concept, and used as ligands for the rhodium(I)-catalyzed asymmetric hydrogenations of ketopantolactone, itaconic acid, dimethyl itaconate, and β-aryl-substituted itaconic acid derivatives. A neutral rhodium(I)-complex of (4R-trans)-dicyclohexyl[[5- [(diphenylphosphino)methyl]-2,2-dimethyl-1,3-dioxolan-4-yl]methyl]phosphine (DIOCP) bearing both a dicyclohexylphosphino group and a diphenylphosphino group was found to be a more efficient catalyst than the original DIOP in the asymmetric hydrogenation of ketopantolactone. Modified DIOPs bearing electron-donating groups at their para positions were efficient ligands for the rhodium(I)-catalyzed assymetric hydrogenations of itaconic acid and its derivatives; in particular, (4R-trans)-[(2,2-dimethyl-1,3-dioxolane-4,5- diyl)bis(methylene)]bis[bis(4'-methoxy-3',5'-dimethylphenyl)phosphine] (MOD- DIOP) bearing both a p-methoxy group and two m,m'-methyl groups on each phenyl group showed much higher enantioselectivity and catalytic activity than DIOP.
Synthesis and Characterization of a Series of High Polarization Difluorinated Ferroelectric Liquid Crystal Dopants
Thurmes, W. N.,Wand, M. D.,Vohra, R. T.,Walba, D. M.
, p. 1 - 7 (2007/10/02)
Two series of difluorinated ferroelectric liquid crystal dopants were synthesized by our researchers.The first series, dubbed the difluoroalkoxy series, had spontaneous polarizations of up to 300 nC/cm2.The second series, dubbed the difluorodia
Syntheses of Unsaturated Trihydroxy C-18 Fatty Acids Isolated from Rice Plants Suffering from Rice Blast Disease
Suemune, Hiroshi,Harabe, Tetsuji,Sakai, Kiyoshi
, p. 3632 - 3637 (2007/10/02)
Two trihydroxy unsaturated C-18 fatty acids isolated from rice plants as agents with activity against blast disease were synthesized from (+)-dimethyl tartrate.Keywords: methyl (9S,12S,13S)-trihydroxyoctadeca-10E,15Z-dienoate; methyl (9S,12S,13S)-trihydroxy-10E-octadecenoate; rice blast disease; fetal calf aorta; (+)-dimethyl tartrate; Wittig-Horner reaction
THE CHEMISTRY OF SILYLATED KETENE ACETALS: AN EFFICIENT STEREOCONTROLLED SYNTHESIS OF N-BENZOYL L-DAUNOSAMINE
Kita, Yasuyuki,Itoh, Fumio,Tamura, Osamu,Ke, Ya Yuan,Tamura, Yasumitsu
, p. 1431 - 1434 (2007/10/02)
N-Benzoyl L-daunosamine was synthesized with high stereoselectivity utilizing a 1,3-addition of ketene silyl acetal (3a) to the chiral nitrone, (Z)-((4R)-trans-2,2,5-trimethyl-1,3-dioxolan-4-yl)methylene((1S)-1-phenylethyl)amine N-oxide (4c) accompanied by a silyl group-transfer in acetonitrile under mild conditions.
SYNTHESIS AND APPLICATION OF A NOVEL BISPHOSPHINE LIGAND, (-)-DIOCP, AS AN UNSYMMETRIZED DIOP TO PROVE THE GENERAL UTILITY OF NEW DESIGNING CONCEPT.
Chiba, Mitsuo,Takahashi, Hitoe,Takahashi, Hisashi
, p. 3675 - 3678 (2007/10/02)
A new chiral bisphosphine-Rh complex (DIOCP-Rh) was found to show excellent catalytic activity and good enantioselectivity for the asymmetric hydrogenation of ketopantolactone proving the general utility of new designing concept.
Biomimetic Studies Using Artificial Systems. II. Enantioselective Thiolysis of D- or L-α-Amino Acid Ester Salts by Thiol-Bearing Chiral Crown Ethers as an Enzyme Model
Sasaki, Shigeki,Kawasaki, Motoji,Koga, Kenji
, p. 4247 - 4266 (2007/10/02)
The rates of transacylation were studied between thiol-bearing chiral crown ethers (1-10) and α-amino acid p-nitrophenyl ester salts.Enantioselectivities, kD/kL ratios, of 6.5 for valine ester salt, 8.7 for phenylalanine ester salt, and 7.7 for valine ester salt were achieved by 1, 5, and 8, respectively.Saturation phenomena of rate acceleration depending on crown concentration were observed and analysis of these data revealed that the chiral recognition occurs in the step of liberation of p-nitrophenol by intra-complex thiolysis, not in the complex-forming step.A possible mechanism for the anantioselectivity is proposed on the basis of the kinetic data.Keywords - crown ether; transacylation; pseudo-first-order rate constant; enantioselectivity; thiolysis; intra-complex reaction; enzyme model
Chiral Electrophilic Synthetic Building Blocks with Four Different Functional Groups from Tartaric Acid, 2,3- and 3,4-Epoxy-butanediol Derivatives in All Four Stereoisomeric Forms
Hungerbuehler, Ernst,Seebach, Dieter
, p. 687 - 702 (2007/10/02)
Efficient and simple procedures have been developed for the preparation of the threo- and erythro-3,4-epoxy-1,2-butanediol derivatives 7 and 9 in both enantiomeric forms from tartaric acid.These epoxides should prove versatile as alkylating reagents in sy
