Hokkaido University Collection of Scholarly and Academic Papers
(65.354 recursos)
HUSCAP (Hokkaido University Collection of Scholarly and Academic Papers) contains peer-reviewed journal articles, proceedings, educational resources and any kind of scholarly works of Hokkaido University.
Mostrando recursos 1 - 20 de 41
1.
Stereoselective synthesis of insect sex pheromone analogs having a fluorine atom on their double bonds - Guan, Tong; Yoshida, Masanori; Ota, Daisuke; Fukuhara, Tsuyoshi; Hara, Shoji
Insect sex pheromone analogs having a fluorine atom on their double bonds,
(9E,11E)-1-acetoxy-9-fluorotetradecadiene, (10E,12E)-13-fluorohexadecadien-1-ol,
(9Z,11E)-1-acetoxy-9-fluorotetradecadiene, (10E,12Z)-13-fluorohexadecadien-1-ol
were stereoselectively synthesized using cross-coupling reactions of alkenylboranes
with (E)- or (Z)-2-fluoro-1-iodo-1-alkenes, stereoselectively prepared from 1-alkynes by
our currently developed methods.
2.
Direct conversion of epoxides to vic-difluorides - Yu, Hong-Wen; Nakano, Yousuke; Fukuhara, Tsuyoshi; Hara, Shoji
vic-Difluoro compounds can be directly prepared from epoxides by reaction with Et3N-3HF and DFMBA under microwave irradiation conditions.
3.
Synthesis of gem-difluorides from aldehydes using DFMBA - Furuya, Tsukasa; Fukuhara, Tsuyoshi; Hara, Shoji
Synthesis of gem-difluorides from aldehydes was effectively achieved using DFMBA and Et3N-3HF under microwave irradiation or conventional thermal heating.
Both aromatic and aliphatic aldehydes could be converted to the corresponding gem-difluorides in good yields.
4.
Selective trifluorination of alkyl aryl sulfides using IF5 - Ayuba, Shinichi; Hiramatsu, Chiharu; Fukuhara, Tsuyoshi; Hara, Shoji
In the reaction of IF5 with alkyl aryl sulfides in heptane under reflux conditions, the arylthio group migrated once and three fluorine atoms were selectively introduced on the alkyl chain. In order to find the reason why the reaction stopped at the trifluorination step, we examined the oxidation potentials of the starting material, a reaction intermediate, and the product, and the time course of the reactions.
5.
Deoxyfluorination of alcohols using N,N-diethyl-α,α-difluoro-(m-methylbenzyl)amine - Kobayashi, Shingo; Yoneda, Atushi; Fukuhara, Tsuyoshi; Hara, Shoji
Deoxyfluorination of alcohols was carried out using
N,N-diethyl-α,α-difluoro-(m-methylbenzyl)amine (DFMBA). Primary alcohols were
effectively converted to fluorides under microwave irradiation or conventional heating.
Deoxyfluorination of an anomeric hydroxy group in sugars by DFMBA proceeded at
below room temperature and glycosyl fluorides could be obtained in good yields. The
deoxyfluorination reaction chemoselectively proceeded and various protecting groups
on the sugar can survive under the reaction conditions.
6.
Selective synthesis of fluorinated carbohydrates using N,N-diethyl-α,α-difluoro-(m-methylbenzyl)amine - Kobayashi, Shingo; Yoneda, Atushi; Fukuhara, Tsuyoshi; Hara, Shoji
Deoxyfluorination of a hydroxy group in rbohydrates was carried out using N,N-diethyl-α,α-difluoro-(m-methylbenzyl)amine. A primary hydroxy group in carbohydrates was effectively converted to the corresponding fluoride under micro-wave irradiation or at 100°C. Deoxyfluorination of hydroxy groups at the anomeric position proceeded at below room temperature, and glycosyl fluorides could be obtained in good yields. The reaction chemoselectively proceeded, and various protecting groups of carbohydrates can survive under the reaction conditions.
7.
α-Fluorination of β-dicarbonyl compounds using p-iodotoluene difluoride under neutral conditions - Yoshida, Masanori; Fujikawa, Komei; Sato, Saeko; Hara, Shoji
A selective introduction of a fluorine atom into the α-position of β-dicarbonyl compounds was achieved using p-iodotoluene difluoride. The reaction proceeded under mild conditions and monofluorination of β-ketoesters, ketoamides, and diketones selectively took place.
9.
Effective Fluorination Reaction with Et3N•3HF Under Microwave Irradiation - Inagaki, Tomotake; Fukuhara, Tsuyoshi; Hara, Shoji
Fluorination reaction of epoxides and alkyl mesylates can beeffectively achieved by reaction with Et3N˙3HFunder microwave irradiation. The reaction time could be greatlyreduced compared to the reaction under thermal conditions. The reactionswere completed in a few minutes and the use of large excess of reagents couldbe avoided.
10.
Regioselective Synthesis ofFluorohydrines via SN2-Type Ring-Opening of Epoxideswith TBABF-KHF2 - Akiyama, Yuriko; Fukuhara, Tsuyoshi; Hara, Shoji
We found that the ring-opening fluorination of terminal epoxidesusing TBABF-KHF2 proceeds with high selectivity throughthe SN2 mechanism. As TBABF-KHF2 iseasily obtainable, is stable, and can be used in glassware, it canbe a useful reagent for 1-fluoro-2-alkanol synthesis from the terminalepoxides.
13.
Asymmetric Conjugate Additionof Arylboronic Acids to Enones Catalyzed by Rhodium-MonodentatePhosphoramidite Complexes in the Presence of Bases - Iguchi, Yuki; Itooka, Ryoh; Miyaura, Norio
Rhodium(I)-catalyzed 1,4-addition of arylboronic acids to α,β-unsaturatedcarbonyl compounds was carried out in the presence of a chiral phosphoramiditeligand based on (R)-binol and dialkylamines.The reaction was significantly accelerated in the presence of abase such as KOH and Et3N, allowing the reaction to becompleted within 6 hours at 50 °C. The additionto 2-cyclohexenone achieved enantioselectivities up to 99%,though they were less effective for 2-cyclopentenone (79% ee),2-cycloheptenone (77% ee) and acyclic enones (31-43% ee).
16.
Rhodium-Catalyzed Addition of Arylboronic Acids to N-Sulfonyl Aldimines - Ueda, Masato; Saito, Atsushi; Miyaura, Norio
The addition of arylboronic acids, ArB(OH)2, to N-phenylsulfonyl aldimines, RCH=NSO2Ph (R = alkyl, aryl, 1-alkenyl), giving R(Ar)CHNHSO2Ph was carried out at 95 °C in the presence of a rhodium catalyst. [Rh(cod)(MeCN)2]BF4 (3 mol%) was found to be the best catalyst for aryl aldimines and Rh(acac)(coe)2/i-Pr3P for alkyl and 1-alkenyl aldimines. The analogous reactions of arylboronic esters, such as 1,2-ethanediol and 1,3-propanediol ester, yielded the addition products in the presence of two equivalents of Et3N.
19.
Recyclability of water-soluble ruthenium–phosphine complex catalysts in multiphase selective hydrogenation of cinnamaldehyde using toluene and pressurized carbon dioxide - Fujita, Shin-ichiro; Akihara, Shuji; Arai, Masahiko
The recyclability of water-soluble ruthenium–phosphine complex catalysts was investigated in water–toluene and in water–pressurized carbon dioxide systems for selective hydrogenation of trans-cinnamaldehyde (CAL). For the first hydrogenation run, the selectivity for cinnamyl alcohol (COL) is high for both toluene and dense CO2, because of interfacial catalysis in which the reaction mainly occurs at the interface between the aqueous phase and the other toluene or dense CO2 phase. The total CAL conversion and the COL selectivity decrease on the second run, more significantly with dense CO2 than toluene. On the subsequent runs, however, less significant changes were observed. During the first...
20.
Batch grinding kinetics of Ethenzamide particles by fluidized-bed jet-milling - Fukunaka, Tadashi; Golman, Boris; Shinohara, Kunio
Ethenzamide solids as a representative active pharmaceutical ingredient (API) were batch-ground by
means of a fluidized-bed jet-mill which is a relatively new equipment and promising for production
in the pharmaceutical field. Thus, the characteristic grinding mechanism was investigated. As a
result, the variation of the residual ratio with grinding time after milling was expressed simply by a
mathematical model using only the first Kapur function, and it was consistent with experimental data
satisfactorily. As the shape of the function was much different from that of inorganic compound and
peculiar to API, a cubic function with respect to particle diameter was defined newly and well fitted
to the...
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