- Preparation method of hydroxyl oxacycloalkane derivative
-
The invention relates to a preparation method of a hydroxyl oxacycloalkane derivative, which comprises the following steps: 1) preparing an initial reaction raw material compound and a catalyst into a raw material solution by using a solvent, and respectively pumping the raw material solution and an oxide material into a continuous flow reactor preheating module from different material conveying equipment for preheating; 2) feeding the material passing through the preheating module into a mixing module, feeding the mixed material into a reaction module, and continuously reacting in the reaction module to obtain a reaction mixture; (3) after the reaction, enabling a reaction mixture to enter a product separation module, and carrying out organic-inorganic separation or solvent removal on reaction liquid at cooling or reaction temperature or raised temperature to obtain a crude product; and refining the crude product to obtain a pure product. According to the method disclosed by the invention, the reaction process can be simplified, the reaction time can be shortened, and the hydroxyl oxacycloalkane derivative can be more efficiently synthesized.
- -
-
Paragraph 0049-0070
(2021/08/14)
-
- Preparation method of hydroxytetrahydrofuran compound
-
The invention discloses a preparation method of a hydroxytetrahydrofuran compound. The method adopts a heterogeneous catalytic reaction step, and is characterized by taking a 3, 4-epoxy tetrahydrofuran compound as a raw material, and carrying out hydrolysis or alcoholysis ring opening, catalytic hydrogenolysis and other catalytic processes to obtain the 3-hydroxytetrahydrofuran compound. The method is green in process, simple to operate, low in catalyst price, relatively simple in separation, efficient and simple to operate, and beneficial to large-scale industrial production of the 3-hydroxytetrahydrofuran compound.
- -
-
Paragraph 0044-0069
(2021/08/19)
-
- Preparation of Highly Active Monometallic Rhenium Catalysts for Selective Synthesis of 1,4-Butanediol from 1,4-Anhydroerythritol
-
1,4-Butanediol can be produced from 1,4-anhydroerythritol through the co-catalysis of monometallic mixed catalysts (ReOx/CeO2+ReOx/C) in the one-pot reduction with H2. The highest yield of 1,4-butanediol was over 80 %, which is similar to the value obtained over ReOx–Au/CeO2+ReOx/C catalysts. Mixed catalysts of CeO2+ReOx/C showed almost the same performance, giving 89 % yield of 1,4-butanediol. The reactivity trends of possible intermediates suggest that the reaction mechanism over ReOx/CeO2+ReOx/C is similar to that over ReOx–Au/CeO2+ReOx/C: deoxydehydration (DODH) of 1,4-anhydroerythritol to 2,5-dihydrofuran over ReOx species on the CeO2 support with the promotion of H2 activation by ReOx/C, isomerization of 2,5-dihydrofuran to 2,3-dihydrofuran catalyzed by ReOx on the C support, hydration of 2,3-dihydrofuran catalyzed by C, and hydrogenation to 1,4-butanediol catalyzed by ReOx/C. The reaction order of conversion of 1,4-anhydroerythritol with respect to H2 pressure is almost zero and this indicates that the rate-determining step is the formation of 2,5-dihydrofuran from the coordinated substrate with reduced Re in the DODH step. The activity of ReOx/CeO2+ReOx/C is higher than that of ReOx–Au/CeO2+ReOx/C, which is probably related to the reducibility of ReOx/C and the mobility of the Re species between the supports. High-valent Re species such as Re7+ on the CeO2 and C supports are mobile in the solvent; however, low-valent Re species, including metallic Re species, have much lower mobility. Metallic Re and cationic low-valent Re species with high reducibility and low mobility can be present on the carbon support as a trigger for H2 activation and promoter of the reduction of Re species on CeO2. The presence of noble metals such as Au can enhance the reducibility through the activation of H2 molecules on the noble metal and the formation of spilt-over hydrogen over noble metal/CeO2, as indicated by H2 temperature-programmed reduction. The higher reducibility of ReOx–Au/CeO2 lowers the DODH activity of ReOx–Au/CeO2+ReOx/C in comparison with ReOx/CeO2+ReOx/C by restricting the movement of Re species from C to CeO2.
- Wang, Tianmiao,Tamura, Masazumi,Nakagawa, Yoshinao,Tomishige, Keiichi
-
p. 3615 - 3626
(2019/07/15)
-
- A strategy of ketalization for the catalytic selective dehydration of biomass-based polyols over H-beta zeolite
-
Biomass contains plentiful hydroxyl groups that lead to an oxygen-rich structure compared to petroleum-based chemicals. Dehydration is the most energy-efficient technique to remove oxygen; however, multiple similar vicinal hydroxyl groups in sugar alcohols impose significant challenges for their selective dehydration. Here, we present a novel strategy to control the etherification site in sugar alcohols by the ketalization of the vicinal-diol group for the highly selective formation of tetrahydrofuran derivatives. A ketone firstly reacts with terminal vicinal hydroxyl groups to form the 1,3-dioxolane structure. This structure of the constrained 1,3-dioxolane ring would improve the accessibility of reactive groups to facilitate intramolecular etherification. As a better leaving group than water, the ketone can also promote intramolecular etherification. Consequently, a range of tetrahydrofuran derivatives are produced in excellent yields with the H-beta zeolite catalyst under mild reaction conditions. This strategy opens up new opportunities for the efficient upgrading of biomass via the modification or protection of hydroxyl groups.
- Che, Penghua,Lu, Fang,Si, Xiaoqin,Ma, Hong,Nie, Xin,Xu, Jie
-
supporting information
p. 634 - 640
(2018/02/14)
-
- One-pot catalytic selective synthesis of 1,4-butanediol from 1,4-anhydroerythritol and hydrogen
-
A physical mixture of ReOx-Au/CeO2 and carbon-supported rhenium catalysts effectively converted 1,4-anhydroerythritol to 1,4-butanediol with H2 as a reductant. The combination of these two catalysts in a one-pot reaction dramatically increased the selectivity of 1,4-butanediol as well as the conversion of 1,4-anhydroerythritol. The yield of 1,4-butanediol reached ~90%, which is the highest yield from erythritol and 1,4-anhydroerythritol so far, furthermore, at a relatively low reaction temperature of 413 K. This reaction involves the ReOx-Au/CeO2-catalyzed deoxydehydration of 1,4-anhydroerythritol to 2,5-dihydrofuran and ReOx/C-catalyzed successive isomerization, hydration and reduction reactions of 2,5-dihydrofuran.
- Wang, Tianmiao,Liu, Sibao,Tamura, Masazumi,Nakagawa, Yoshinao,Hiyoshi, Norihito,Tomishige, Keiichi
-
supporting information
p. 2547 - 2557
(2018/06/18)
-
- A pharmaceutical intermediates (S)-3 - hydroxy tetrahydrofuran preparation method (by machine translation)
-
The invention provides a pharmaceutical intermediate (S)- 3 - hydroxy tetrahydrofuran preparation method. The method other than racemic 1, 2, 4 - butanetriol as raw materials synthesis of racemic 3 - hydroxy tetrahydrofuran, then esterification of racemic tetrahydrofuran-yl - 3 - fatty acid ester. By lipase hydrolysis in the racemic mixture of (R)- tetrahydrofuran-based - 3 - fatty acid ester after, in in the hydrolysis product under the condition of separating, using the mitsunobu reaction will be hydrolyzed to obtain the of (R)- 3 - hydroxy tetrahydrofuran is converted into (S)- tetrahydrofuran-based - 3 - carboxylic acid ester, finally under alkaline condition all of the tetrahydrofuran ester hydrolyzed to obtain the final product (S)- 3 - hydroxy tetrahydrofuran. (by machine translation)
- -
-
Paragraph 0040
(2017/08/31)
-
- SYNTHESIS OF R-GLUCOSIDES, SUGAR ALCOHOLS, REDUCED SUGAR ALCOHOLS, AND FURAN DERIVATIVES OF REDUCED SUGAR ALCOHOLS
-
Disclosed herein are methods for synthesizing 1,2,5,6-hexanetetrol (HTO), 1,6 hexanediol (HDO) and other reduced polyols from C5 and C6 sugar alcohols or R glycosides. The methods include contacting the sugar alcohol or R-glycoside with a copper catalyst, most desirably a Raney copper catalyst with hydrogen for a time, temperature and pressure sufficient to form reduced polyols having 2 to 3 fewer hydoxy groups than the starting material. When the starting compound is a C6 sugar alcohol such as sorbitol or R-glycoside of a C6 sugar such as methyl glucoside, the predominant product is HTO. The same catalyst can be used to further reduce the HTO to HDO.
- -
-
Paragraph 0077
(2017/05/31)
-
- Selective C?O Hydrogenolysis of Erythritol over Supported Rh-ReOx Catalysts in the Aqueous Phase
-
Bimetallic Rh-ReOx (Re/Rh molar ratio 0.4–0.5) catalysts supported on TiO2 and ZrO2 were prepared by the successive impregnation of dried and calcined unreduced supported Rh catalysts. Their catalytic performances were evaluated in the hydrogenolysis of erythritol to butanetriols (BTO) and butanediols (BDO) in aqueous solution at 150–240 °C under 30–120 bar H2. The activity depended on the nature of the support, and the highest selectivity to BTO and BDO at 80 % conversion was 37 and 29 %, respectively, in the presence of 3.7 wt %Rh-3.5 wt %ReOx/ZrO2 at 200 °C under 120 bar. The characterization of the catalysts by CO chemisorption, TEM with energy-dispersive X-ray spectroscopy, thermogravimetric analysis with MS, and X-ray photoelectron spectroscopy suggests a different distribution and reducibility of Re species over the supported Rh nanoparticles, which depends on the support.
- Said, Achraf,Da Silva Perez, Denilson,Perret, Noémie,Pinel, Catherine,Besson, Michèle
-
p. 2768 - 2783
(2017/07/28)
-
- Origins of stereoselectivity in evolved ketoreductases
-
Mutants of Lactobacillus kefir short-chain alcohol dehydrogenase, used here as ketoreductases (KREDs), enantioselectively reduce the pharmaceutically relevant substrates 3-thiacyclopentanone and 3-oxacyclopentanone. These substrates differ by only the heteroatom (S or O) in the ring, but the KRED mutants reduce them with different enantioselectivities. Kinetic studies show that these enzymes are more efficient with 3-thiacyclopentanone than with 3-oxacyclopentanone. X-ray crystal structures of apo- and NADP+-bound selected mutants show that the substrate-binding loop conformational preferences are modified by these mutations. Quantum mechanical calculations and molecular dynamics (MD) simulations are used to investigate the mechanism of reduction by the enzyme. We have developed an MD-based method for studying the diastereomeric transition state complexes and rationalize different enantiomeric ratios. This method, which probes the stability of the catalytic arrangement within the theozyme, shows a correlation between the relative fractions of catalytically competent poses for the enantiomeric reductions and the experimental enantiomeric ratio. Some mutations, such as A94F and Y190F, induce conformational changes in the active site that enlarge the small binding pocket, facilitating accommodation of the larger S atom in this region and enhancing S-selectivity with 3-thiacyclopentanone. In contrast, in the E145S mutant and the final variant evolved for large-scale production of the intermediate for the antibiotic sulopenem, R-selectivity is promoted by shrinking the small binding pocket, thereby destabilizing the pro-S orientation.
- Noey, Elizabeth L.,Tibrewal, Nidhi,Jiménez-Osés, Gonzalo,Osuna, Sílvia,Park, Jiyong,Bond, Carly M.,Cascio, Duilio,Liang, Jack,Zhang, Xiyun,Huisman, Gjalt W.,Tang, Yi,Houk, Kendall N.
-
p. E7065 - E7072
(2016/01/09)
-
- METHOD FOR PRODUCING 3-HYDROXYTETRAHYDROFURAN AND METHOD FOR PRODUCING 1, 3-BUTANE DIOL
-
An object of the present invention is to provide a method for producing 3-hydroxytetrahydrofuran that can be used as a raw material for 1,3-butane diol, using as a raw material a compound that can be derived from biomass. The present invention relates to a method for producing 3-hydroxytetrahydrofuran including a step of reacting 1,4-anhydroerythritol and hydrogen to produce 3-hydroxytetrahydrofuran. In the production method, the step of reacting 1,4-anhydroerythritol and hydrogen is preferably allowed to proceed in the presence of a catalyst comprising a carrier and at least one oxide selected from the group consisting of an oxide of a Group 6 element and an oxide of a Group 7 element, the oxide being supported on the carrier.
- -
-
-
- Mild deprotection of PMB ethers using tert-butyl bromide
-
A convenient and high yielding method for the cleavage and scavenging of p-methoxybenzyl protecting group of several alcohols using tert-butyl bromide in refluxing acetonitrile is described. Under these mild conditions other protecting groups such as acid sensitive allyl, benzyl, and Me3CPh2Si ethers, or isopropylidene acetals were unchanged. Interestingly, a selective alkoxy-PMB cleavage was observed in the presence of a PMB phenoxy ether.
- Rival, Nicolas,Albornoz Grados, Arantxa,Schiavo, Lucie,Colobert, Fran?oise,Hanquet, Gilles
-
p. 6823 - 6826
(2015/11/27)
-
- Cyclic Ether Synthesis via Palladium-Catalyzed Directed Dehydrogenative Annulation at Unactivated Terminal Positions
-
Here, a palladium-catalyzed functionalization of unactivated sp3 C-H bonds with internal alcohol nucleophiles is described. Directed by an oxime-masked alcohol, annulation chemoselectively occurs at the β position, leading to a range of aliphatic cyclic ethers with four- to seven-membered rings. Tethered primary, secondary, and tertiary free hydroxyl groups can all react to give the corresponding cyclized products. In addition, benzyl and silyl protected alcohols can also be directly coupled. An sp3 C-H activation/intramolecular SN2 pathway was proposed.
- Thompson, Samuel J.,Thach, Danny Q.,Dong, Guangbin
-
supporting information
p. 11586 - 11589
(2015/09/28)
-
- Lewis acid promoted ruthenium(II)-catalyzed etherifications by selective hydrogenation of carboxylic acids/esters
-
Ethers are of fundamental importance in organic chemistry and they are an integral part of valuable flavors, fragrances, and numerous bioactive compounds. In general, the reduction of esters constitutes the most straightforward preparation of ethers. Unfortunately, this transformation requires large amounts of metal hydrides. Presented herein is a bifunctional catalyst system, consisting of Ru/phosphine complex and aluminum triflate, which allows selective synthesis of ethers by hydrogenation of esters or carboxylic acids. Different lactones were reduced in good yields to the desired products. Even challenging aromatic and aliphatic esters were reduced to the desired products. Notably, the in situ formed catalyst can be reused several times without any significant loss of activity. An assist from Al: A bifunctional catalyst system consisting of a Ru/phosphine complex and aluminum triflate allows selective hydrogenation of esters to ethers. A variety of lactones were reduced to the desired products in good yields. The catalyst further provides a general method for the reduction of linear esters and reductive etherification of carboxylic acids with alcohols.
- Li, Yuehui,Topf, Christoph,Cui, Xinjiang,Junge, Kathrin,Beller, Matthias
-
supporting information
p. 5196 - 5200
(2015/04/27)
-
- NOVEL PROCESS FOR THE MANUFACTURE OF 3-OXO-TETRAHYDROFURAN
-
This invention relates to a novel method for the preparation of 3-oxotetrahydrofuran comprising oxidating 3-hydroxy-tetrahydrofuran in the presence of a catalytic amount of TEMPO with trichloroisocyanuric acid.
- -
-
Page/Page column 7
(2014/09/29)
-
- NOVEL PROCESS FOR THE MANUFACTURE OF 3-OXO-TETRAHYDROFURAN
-
This invention relates to a novel method for the preparationof 3-oxotetrahydrofurancomprising oxidating 3-hydroxy-tetrahydrofuran in the presence of a catalytic amount of TEMPO with trichloroisocyanuric acid.
- -
-
Page/Page column 6
(2014/09/29)
-
- NOVEL PROCESS FOR THE MANUFACTURE OF 3-OXO-TETRAHYDROFURAN
-
This invention relates to a novel method for the preparation of 3-oxo-tetrahydrofuran comprising oxidizing 3-hydroxy-tetrahydrofuran in the presence of a catalytic amount of 2,2,6,6-tetramethyl-piperidine-N-oxyl (TEMPO) with trichloroisocyanuric acid.
- -
-
Paragraph 0027
(2014/09/30)
-
- Oxorhenium-catalyzed deoxydehydration of glycols and epoxides
-
The conversion of renewable cellulosic biomass into hydrocarbons has attracted significant attention with a growing demand of sustainability. MeReO3 catalyzes the deoxydehydration (DODH) of glycols and epoxides to alkenes by primary and secondary alcohols (5-nonanol, 3-octanol, 1-butanol) in the benzene solvent. The product yield range from moderate to excellent.
- Davis, Jacqkis,Srivastava, Radhey S.
-
supporting information
p. 4178 - 4180
(2014/07/22)
-
- SPIROHYDANTOIN COMPOUNDS AND THEIR USE AS SELECTIVE ANDROGEN RECEPTOR MODULATORS
-
The present invention relates to a compound of formula (1-1 ) in free form or in pharmaceutically acceptable salt form in which the substituents are as defined in the specification; to its preparation, to its use as a medicament and to medicaments comprising it. The present invention further provides a combination of pharmacologically active agents and a pharmaceutical composition.
- -
-
Page/Page column 94
(2013/09/12)
-
- 3-PYRIDYL CARBOXAMIDE-CONTAINING SPLEEN TYROSINE KINASE (Syk) INHIBITORS
-
The invention provides certain 3-pyridyl carboxamide-containing compounds of the Formula (I) (I) or pharmaceutically acceptable salts thereof, wherein A and B are as defined herein. The invention also provides pharmaceutical compositions comprising such compounds, and methods of using the compounds for treating diseases or conditions mediated by Spleen Tyrosine Kinase (Syk) kinase.
- -
-
Paragraph 00181
(2013/04/24)
-
- 2-PYRIDYL CARBOXAMIDE-CONTAINING SPLEEN TYROSINE KINASE (SYK) INHIBITORS
-
The invention provides certain 2-pyridyl carboxamide-containing compounds of the Formula (I) or pharmaceutically acceptable salts thereof, wherein A and B are as defined herein. The invention also provides pharmaceutical compositions comprising such compounds, and methods of using the compounds for treating diseases or conditions mediated by Spleen Tyrosine Kinase (Syk) kinase.
- -
-
Paragraph 00265
(2013/04/24)
-
- Intramolecular etherification of five-membered cyclic carbonates bearing hydroxyalkyl groups
-
We report a new one-pot synthetic route to tetrahydrofuran derivatives, which were unexpectedly produced under basic conditions by intramolecular etherification of substituted five-membered cyclic carbonates. For alcohols with vicinal hydroxyl groups, and additional OH groups at the β-position, intramolecular etherification leading to 3-hydroxytetrahydrofuran derivatives was observed. These reactions were studied for compounds having from 2 to 6 hydroxyl groups per molecule, and the mechanism was proposed. The developed method provides a new environmentally friendly approach to the synthesis of five-membered cyclic ether derivatives under non-acidic conditions. The Royal Society of Chemistry.
- Tomczyk, Karolina M.,Gunka, Piotr A.,Parzuchowski, Pawel G.,Zachara, Janusz,Rokicki, Gabriel
-
p. 1749 - 1758
(2013/02/22)
-
- Iridium-catalyzed borylation of secondary C-H bonds in cyclic ethers
-
The borylation of secondary C-H bonds, specifically secondary C-H bonds of cyclic ethers, with a catalyst generated from tetramethylphenanthroline and an iridium precursor is reported. This borylation occurs with unique selectivity for the C-H bonds located β to the oxygen atoms over the weaker C-H bonds located α to oxygen atoms. Mechanistic studies imply that the C-H bond cleavage occurs directly at the β position rather than at the α position followed by isomerization of a reaction intermediate.
- Liskey, Carl W.,Hartwig, John F.
-
supporting information; experimental part
p. 12422 - 12425
(2012/09/05)
-
- METHODS OF PURIFYING 1,2,4-BUTANETRIOL AND COMPOSITIONS INCLUDING 1,2,4-BUTANETRIOL
-
Methods of purifying BT are disclosed. The method comprises adding at least one polyhydroxyl compound to a crude BT mixture comprising BT and at least one boron-containing compound to form a polyhydroxyl compound/BT mixture. In one embodiment, the polyhydroxyl compound/BT mixture is then heated to a temperature greater than the boiling point of BT but less than the boiling point of the at least one polyhydroxyl compound. In another embodiment, the polyhydroxyl compound/BT mixture is heated to a temperature greater than the melting point of the polyhydroxyl compound, and then to a temperature greater than the boiling point of BT but less than the boiling point of the at least one polyhydroxyl compound. A composition comprising BT is also disclosed.
- -
-
Page/Page column 3-4
(2011/06/10)
-
- Enhancement of cyclic ether formation from polyalcohol compounds in high temperature liquid water by high pressure carbon dioxide
-
Cyclic ethers were produced by a dehydration reaction of polyalcohol compounds in high temperature liquid water, which was accelerated by the presence of carbon dioxide dissolved in the water. 3-hydroxytetrahydrofuran was produced by the dehydration of 1,2,4-butanetriol. Both tetrahydrofurfuryl alcohol and 3-hydroxytetrahydropyran were produced by the dehydration of 1,2,5-pentanetriol. Five-membered cyclic ethers were formed faster than six-membered cyclic ethers and the formation rates of the cyclic ethers depended strongly on the structure of the polyalcohol compounds. The position of the hydroxyl groups is crucial for the efficient intramolecular dehydration.
- Yamaguchi, Aritomo,Hiyoshi, Norihito,Sato, Osamu,Bando, Kyoko K.,Shirai, Masayuki
-
experimental part
p. 48 - 52
(2010/04/22)
-
- Thermodynamic equilibria between polyalcohols and cyclic ethers in high-temperature liquid water
-
Thermodynamic equilibrium constants between polyalcohols and cyclic ethers in water at 573 K were determined by measuring their concentrations after the long-term reaction in a batch reactor. Intramolecular dehydration reactions of polyalcohols were important for conversion of biomass-derived carbohydrates; however, the yields of products were limited by thermodynamic equilibria between polyalcohols and products. All the thermodynamic equilibrium constants were estimated by the long-term dehydration reaction of 1 mol ·dm-3 polyalcohol aqueous solutions at 573 K. The thermodynamic equilibrium constants between butanepolyols or pentanepolyols and five-membered or six-membered cyclic ethers were within a range from (39 to 337) mol ·dm-3.
- Yamaguchi, Aritomo,Hiyoshi, Norihito,Sato, Osamu,Bando, Kyoko K.,Masuda, Yoshio,Shirai, Masayuki
-
experimental part
p. 2666 - 2668
(2010/07/08)
-
- METHOD FOR PREPARING 3-HYDROXYTETRAHYDROFURAN USING CYCLODEHYDRATION
-
Disclosed is a method of preparing 3-hydroxytetrahydrofuran using cyclodehydration. More particularly, this invention relates to a method of preparing 3-hydroxytetrahydrofuran, including subjecting 1,2,4-butanetriol to cyclodehydration under reaction conditions of a reaction temperature of 30~180°C and reaction pressure of 5000 psig or less in the presence of a strong acid cation exchange resin catalyst having a sulfonic acid group as an exchange group. According to the method of this invention, 3-hydroxytetrahydrofuran can be economically prepared at higher yield and productivity than when using conventional methods.
- -
-
Page/Page column 6
(2008/06/13)
-
- METHOD FOR PRODUCING 3-AMINOMETHYLTETRAHYDROFURAN DERIVATIVE
-
An object of the present invention is to provide a process for producing a 3-cyanotetrahydrofuran derivative in a high yield from inexpensive industrial materials. According to the present invention, a 3-aminomethyltetrahydrofuran derivative is produced by preparing a 3-cyanotetrahydrofuran derivative in a high yield from an inexpensive and industrially easily available malic acid derivative, and reducing the cyano group of the 3-cyanotetrahydrofuran derivative.
- -
-
-
- METHOD FOR PRODUCING 3-AMINOMETHYLTETRAHYDROFURAN DERIVATIVE
-
Disclosed is a method for highly efficiently producing a 3-aminomethyltetrahydrofuran derivative from a low-cost industrial raw material. Specifically, a 3-cyanotetrahydrofuran derivative is produced at high yield from a low-cost, industrially easily-available malic acid derivative, and then a 3-aminomethyltetrahydrofuran derivative is produced by reducing the cyano group of the 3-cyanotetrahydrofuran derivative.
- -
-
Page/Page column 33
(2008/06/13)
-
- Deprotection of benzyl and p-methoxybenzyl ethers by chlorosulfonyl isocyanate-sodium hydroxide
-
CSI-NaOH procedure provided a new and mild methodology for the deprotection of benzyl and p-methoxybenzyl ethers without affecting the other functional groups under similar reaction conditions.
- Kim, Ji Duck,Han, Gyoonhee,Zee, Ok Pyo,Jung, Young Hoon
-
p. 733 - 735
(2007/10/03)
-
- Intramolecular rearrangement of epoxides generated in situ over titanium silicate molecular sieves
-
Open chain unsaturated alcohols 1, having the general formula R1R2C=CH(CH2)CR1R2OH (where R1, R2 = H or CH3, and n = 1-3) and carbocyclic unsaturated alcohols of similar type have been efficiently cyclized to the corresponding hydroxytetrahydrofuran or hydroxytetrahydropyran over titanium silicate molecular sieves (TS-1 and Ti-beta), in one pot under mild liquid phase reaction conditions using dilute hydrogen peroxide as oxidant. When the hydroxy nucleophile may attack either of the activated carbon atoms of the epoxides generated in situ, to lead to a derivative of tetrahydrofuran or tetrahydropyran, the former exclusively formed. The regioselectively for such reaction is 100%. When R1 or R2 = CH3, among the diasteroisomeric products trans predominates over cis. In this cyclization reaction titanium silicate epoxidizes the olefin and successively catalyzes the opening of the oxirane ring via intramolecular attack of hydroxy oxygen. Thus the behavior of titanium sites is bifunctional in nature. However, for bicyclic unsaturated alcohols, because of geometric restriction, activity of medium pore TS-1 is very low. Ti-beta synthesized by dry gel conversion has been found to be an efficient catalyst in oxidative cyclization of such bulky organic substrates as α-terpineol, isopulegol, and trans-p-menth-6-ene-2,8-diol to their corresponding tetrahydrofuranols or tetrahydropyranols with a very high regioselectivity.
- Bhaumik, Asim,Tatsumi, Takashi
-
p. 349 - 356
(2007/10/03)
-
- Regio- and enantioselective cyclization of epoxy alcohols catalyzed by a [Co(III)(salen)] complex
-
The intramolecular cyclization of epoxy alcohols was catalyzed with excellent regio- and enantiocontrol by a [Co(III)(salen)] complex. High endo selectivity was observed for the enantioselective cyclization of terminal epoxy alcohols [Eq. (a)], while the reaction of meso substrates produced novel cyclic and bicyclic ethers in good yields and high enatiopurity. TBME = tert-butyl methyl ether.
- Wu, Michael H.,Hansen, Karl B.,Jacobsen, Eric N.
-
p. 2012 - 2014
(2007/10/03)
-
- Highly efficient and regioselective cyclization catalyzed by titanium silicate-1
-
Highly regioselective cyclization of 3,4, 4,5 and 5,6 unsaturated alcohols to tetrahydrofuranols and tetrahydropyranols is reported using the TS-1-H2O2 system for the first time.
- Bhaumik, Asim,Tatsumi, Takashi
-
p. 463 - 464
(2007/10/03)
-
- rac-3,4-DIHYDROXYBUTYLARSONIC ACID: A KEY INTERMEDIATE FOR ISOSTERIC ARSONOLIPIDS
-
Synthetic routes starting from 4-bromobut-1-ene and leading to rac-dihydroxybutylarsonic acid and diphenyl rac-3,4-dihydroxybutyldithioarsonite were explored.All of them gave overall yields 5-16percent.Some properties of the free acid and its dilithium salt are described. Key words: Arsonic acids, (diethylamino)chlorarsine, the Mayer reaction,salts of arsonic acids, cyclization of arsonic acids.
- Serves, Spyros V.,Sotiropoulos, Demetrios N.,Ioannou, Panayiotis V.,Mutenda, Esther K.,Sparkes, Michael J.,Dixon, Henry B.F.
-
-
- Stereocontrolled Formation of Functionalized erythro-1,2-Diols via Hydroboration of 2-Alkyl-4,5-dihydrofurans
-
trans-2-Alkyl-3-hydroxytetrahydrofurans, prepared by the stereospecific hydroboration / oxidation reaction of 2-alkyl-4,5-dihydrofurans, were regioselectively cleaved with (CH3)3SiCl/NaI to afford 1-iodo-erythro-3,4-diols in CH3CN or the corresponding acetonide derivatives in CH3COCH3.
- Amouroux, Roger,Slassi, Abdelmalik,Saluzzo, Christine
-
p. 1965 - 1970
(2007/10/02)
-
- ORGANOTINS AS ETHERIFICATION CATALYSTS. III. ETHERIFICATIONS AND HYDRO-HYDROXY-ELIMINATIONS PROMOTED BY BUTYLTIN TRICHLORIDE
-
Butyltin trichloride, as a catalyst precursor, promotes the following processes: (i) etherification of 2,3-unsaturated alcohols, (ii) etherification of functional diols, (iii) cyclization of 2,5-hexanedione, and (iv) dehydration of cyclic diols.Many examples are reported.
- Marton, Daniele,Slaviero, Pierangelo,Tagliavini, Giuseppe
-
p. 7099 - 7108
(2007/10/02)
-
- Hydroboration of Prochiral Olefins with Chiral Lewis Base-Borane Complexes: Relationship to the Mechanism of Hydroboration
-
Alcohols with up to 19percent enantiomeric excess were obtained on hydroboration/oxidation of representative prochiral olefins using N-isobornyl-N-methylaniline-borane or N-benzyl-N-isopropyl-α-methylbenzylamine-borane indicating that the Lewis base is present in the hydroboration transition state.
- Narayana, Chatla,Periasamy, Mariappan
-
p. 1857 - 1859
(2007/10/02)
-
- Catalytic Formation of Hydrogen and C-C Bonds on Illuminated Zinc Sulfide Generated from Zinc Dithiolenes
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UV irradiation of bis(cis-1,2-dicyano-1,2-ethylenedithiolate)zinc bis(tetrabutylammonium) in aqueous tetrahydrofuran (THF) or 2,5-dihydrofuran (2,5-DHF) leads to the semiconductor n-ZnS which photocatalyses an efficient H2 evolution (Φ300nm =/>0.1) coupled to a chemoselective dehydrodimerization of the cyclic ether.The reacion does not occur in pure water nor in dry ethers. n-ZnS, which immediately photocorrodes in pure water, becames very stable in the presence of 2,5-DHF. 2,3-DHF and six-membered ethers do not dehydrodimerize or prevent photocorrosion.The H2-evolution rate increases linearity with light intensity and does not change as a function of temperature (20-50 deg C) or pH (4-10).In the case of 2,5-DHF, the previously unknown 2,2'-, 2,3', and 3,3'-dehydrodimers are formed in the ratio of 1:2:1, respectively, on analytical and preparative scales.With THF, the reaction proceeds regioselectively with the exclusive formation of the 2,2'-dihydrodimer.A complete material balance shows that no water is consumed although the initial gas phase contains more than 90percent D2 when D2O is used.The latter value decreases with increasing turnover and is accompained by the formation of HD and H2.These results are compatible with the reduction of water to hydrogen by conduction band electrons.The dehydrodimers are produced by dimerization of the corresponding radicals formed most likely by hole oxidation of the cyclic ether with subsequent deprotonation.Comparison with reactions of OH generated in homogeneous solution reveals a higher selectivity for the catalytic ZnS system.
- Zeug, N.,Buecheler, J.,Kisch, H.
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p. 1459 - 1465
(2007/10/02)
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- Hydroboration. 71. Hydroboration of Representative Heterocyclic Olefins with Borane-Methyl Sulfide, 9-Borabicyclononane, Dicyclohexylborane, and Disiamylborane. Synthesis of Heterocyclic Alcohols
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The hydroboration of representative heterocycles bearing an endocyclic double bond with borane-methyl sulfide (BMS), 9-borabicyclononane (9-BBN), dicyclohexylborane (Chx2BH), and disiamylborane (Sia2BH) was investigated systematically to establish the optimum conditions for the clean and quantitative hydroboration.The hydroboration of 2,3- and 2,5-dihydrofurans with BMS (3:1 molar ratio) at 25 deg C for 1 h affords the trialkylborane, readily oxidized to 3-hydroxytetrahydrofuran in excellent yield.However, preparation of the corresponding dialkylboranes from these olefins using 2 olefin/BMS was not possible even at 0 deg C.Excess hydride and prolongated reaction time cause ring cleavage of the alkylboranes to yield both unsaturated alcohol and the dihydroborated products 1,3- and 1,4-pentanediols.Hydroboration of both 2,3-dihydrothiophene and 2-methyl-4,5-dihydrofuran with BMS proceeds cleanly to the trialkylborane stage, oxidized to the corresponding alcohols in almost quantitative yields.Hydroboration of 3-pyrroline with BMS could not be achieved with the unprotected nitrogen atom.Such hydroboration could be accomplished by protecting the nitrogen atom with the benzyloxycarbonyl group affording the trialkylborane, readily converted to N-(benzyloxycarbonyl)-3-pyrrolidinol in good yield.Conditions for a clean hydroboration of these heterocyclic five-membered olefins with 9-BBN, Chx2BH, and Sia2BH were also established.In all cases clean trialkylboranes were obtained, readily oxidized to heterocyclic alcohols in high yields. 3,4-Dihydropyran, on hydroboration with BMS, followed by oxidation, affords 3-hydroxytetrahydropyran in good yield.However, ring cleavage in this case is greater when compared to 2,3-dihydrofuran. 2-Methoxy- or 2-ethoxy-3,4-dihydro-2H-pyran readily undergo hydroboration with BMS to the trialkylboranes, oxidized to the corresponding trans and cis alcohols in a 7:3 ratio.As the steric requirements of the dialkylborane are increased, more trans alcohol is formed.Thus at 0 deg C, the ratios of trans to cis alcohols were increased from 1:1 to 7:3 and then to 8:2 with 9-BBN, Chx2BH, and Sia2BH, respectively.N-(Benzyloxycarbonyl)-1,2,3,6-tetrahydropyridine is readily hydroborated with BMS, 9-BBN, Chx2BH, and Sia2BH to the corresponding trialkylboranes, readily oxidized to N-(benzyloxycarbonyl)-3- and -4-piperidinols in good yield.Strongly basic groups in the heterocyclic ring can greatly reduce the ease of hydroboration, and the introduction of boron β to the heteroatom can lead to elimination.However, both problems can be avoided to provide ready hydroboration-oxidation of heterocyclic olefins.
- Brown, Herbert C.,Prasad, J. V. N. Vara,Zee, Sheng-Hsu
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p. 1582 - 1589
(2007/10/02)
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- REGIO- AND STEREO-SELECTIVITIES IN THE TITANIUM COMPLEX CATALYZED HYDROBORATION OF CARBON-CARBON DOUBLE BONDS IN VARIOUS UNSATURATED COMPOUNDS
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The titanium complex prepared from TiCl3 and NaBH4 in THF in the presence of 18-crown-6 promotes the catalytic hydroboration of carbon-carbon double bonds in alkenes, alkadienes and unsaturated ethers with NaBH4, giving sodium organoborates which can be converted into alcohols by oxidation with H2O2/CH3ONa.The reaction proceeds with high regio- and stereo-selectivities.
- Lee, Hyung Soo,Isagawa, Kakuzo,Toyoda, Hiromu,Otsuji, Yoshio
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p. 673 - 676
(2007/10/02)
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- TRANSPOSITION DES OXIRANNES-ETHANOLS PAR L'INTERMEDIAIRE D'ALCOXYETAINS
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Oxiraneethoxytributyltins prepared from the corresponding oxiraneethanols, on heating at 200 deg C gave, after demetalation with isophthalic acid, 2-oxetanemethanols and/or 3-oxolanols.As appears from about thirty rearrangements the choice between oxetane and oxolane formation is dependent on: (1) the relative degree of substitution of the oxirane ring; cyclization occuring predominantly at the more substituted carbon; and (2) the configuration of the oxirane ring, when both its ends are equally substituted; cis form being more suitable for genaration of the smaller ring.The reaction is shown to proceed with inversion of configuration at the site of oxygen attack.The results of attempts to perform the rearrangement in dilute-phase or throught alkaline metal alkoxides in various media support the conclusion that there is a large contribution by electrophilic assistance to the oxirane ring opening.Such assistance can be efficiently provided by a tin atom in a push-pull mechanism which accomodates all the facts.The present method of oxiraneethanol rearrangement may offer a convenient route to functional oxetanes.
- Bats, J. -P.,Moulines, J.,Picard, P.,Leclercq, D.
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p. 2139 - 2146
(2007/10/02)
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- TRANSPOSITION DES OXIRANNES-ETHANOLS PAR L'INTERMEDIAIRE D'ALCOXYETAINS. INFLUENCE DE LA CONFIGURATION DE L'OXIRANNE
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The transposition of oxirane-ethanols, through alkoxytin compounds, into oxetane-2-methanols and/or oxolan-3-ols (tetrahydrofuran-3-ols) is dependent upon the oxirane configuration.Cis configuration is more suitable for the formation of the smallest ring.Steric hindrance is not sufficient enough to explain the results.
- Bats, J.-P.,Moulines, J.,Picard, P.,Leclerq, D.
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p. 3051 - 3054
(2007/10/02)
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