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Asymmetric Dihydroxylation (asymmetric + dihydroxylation)
Kinds of Asymmetric Dihydroxylation Selected AbstractsAsymmetric Dihydroxylation of ,,,-Unsaturated Carboxylic Esterswith Trisubstituted C=C Bonds , Enantioselective Syntheses of Trisubstituted ,-ButyrolactonesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2006Tobias Kapferer Abstract ,,,-Unsaturated esters with stereodefined trisubstitued C=C double bonds were prepared by the Arndt,Eistert homologation of ,,,-unsaturated carboxyl halides, by two-step methoxycarbonylation of allylbarium reagents, by deconjugation of ,,,-unsaturated esters, and by Horner,Wadsworth,Emmons variants of the Stobbe condensation. Sharpless asymmetric dihydroxylation of the ,,,-unsaturated esters, followed by spontaneous cyclization, afforded ,-hydroxy-,-lactones in moderate to good yields and with enantiomeric excesses of up to 97,%. Similarly, tetrahydroxy-,-lactones were obtained from diunsaturated esters; these lactones were converted into a bislactone and an unsaturated ,-hydroxy ,-lactone. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Sharpless Asymmetric Dihydroxylation of Olefins in WaterSurfactant Media with Recycling of the Catalytic System by Membrane NanofiltrationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2008Abstract This paper presents a new and more sustainable alternative approach for the Sharpless catalytic asymmetric dihydroxylation (AD) of olefins using a water/surfactant system as reaction media. The AD reaction was performed using several cationic and anionic surfactants allowing yields and enantiomeric excesses higher or comparable with the conventional systems (using organic mixtures). The use of this water/surfactant medium offers the additional advantage of performing the reactions without the need of a slow addition of olefins. Asymmetric dihydroxylation of 1-hexene in a 1.5,mM sodium cholate aqueous solution, using N -methylmorpholine N -oxide (NMO) as co-oxidant was selected as model system to evaluate the feasibility of recycling the Sharpless catalytic system by nanofiltration. The reaction media was processed by nanofiltration, the product was isolated in the permeate, whereas the catalytic system and surfactant were retained by the membrane and recycled through six successive reactions, improving the catalyst turn-over number. The experimental results were compared with the ones calculated on the basis of mass balances, membrane rejections to product and reaction yields. [source] A Novel Microencapsulated Osmium Catalyst Using Cross-Linked Polystyrene as an Efficient Catalyst for Asymmetric Dihydroxylation of Olefins in WaterADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2005Tasuku Ishida Abstract A novel microencapsulated osmium catalyst (PSresin-MC Os) was developed using cross-linked polystyrene. The concept of this method may go beyond that of microencapsulation. The catalyst was successfully used in asymmetric dihydroxylation in water, and it was recovered quantitatively by simple filtration and reused several times without loss of activity. The shape of the catalyst was maintained even after several uses. Moreover, no leaching of the Os component was detected. [source] Biocatalytic Asymmetric Dihydroxylation of Conjugated Mono- and Poly-alkenes to Yield Enantiopure Cyclic cis -DiolsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2005Derek Abstract Dioxygenase-catalysed asymmetric dihydroxylation, of a series of conjugated monoalkenes and polyenes, was found to yield the corresponding monols and 1,2-dihydrodiols. The diol metabolites were obtained from monosubstituted, gem -disubstituted, cis -disubstituted, and trisubstituted alkene substrates, using whole cells of Pseudomonas putida strains containing toluene and naphthalene dioxygenases. Dioxygenase selection and alkene type were established as important factors, in the preference for dioxygenase-catalysed 1,2-dihydroxylation of conjugated alkene or arene groups, and monohydroxylation at benzylic or allylic centres. Competition from allylic hydroxylation of methyl groups was observed only when naphthalene dioxygenase was used as biocatalyst. The structures, enantiomeric excess values and absolute configurations of the bioproducts, were determined by a combination of stereochemical correlation, spectroscopy (NMR and CD) and X-ray diffraction methods. cis -1,2-Diol metabolites from arenes, cyclic alkenes and dienes were generally observed to be enantiopure (>98% ee), while 1,2-diols from acyclic alkenes had lower enantiomeric excess values (<88% ee). The enantiopure cis -diol metabolite of a gem -disubstituted fulvene was used as precursor in a new chemoenzymatic route to a novel C2 -symmetrical ketone. [source] ChemInform Abstract: Osmium-Catalyzed Asymmetric Dihydroxylation by Carbon Dioxide Activated Hydrogen Peroxide and N-Methylmorpholine.CHEMINFORM, Issue 23 2008Bharathi Balagam Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Catalytic Asymmetric Dihydroxylation of Olefins with Recyclable Osmate-Exchanged Chloroapatite Catalyst.CHEMINFORM, Issue 28 2007Sanjay K. Dehury Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] An Economical, Highly Efficient and Recyclable Catalyst System for Asymmetric Dihydroxylation of Olefins.CHEMINFORM, Issue 35 2005Ying Jin Abstract For Abstract see ChemInform Abstract in Full Text. [source] Asymmetric Synthesis of Aryloxypropanolamines via OsO4 -Catalyzed Asymmetric Dihydroxylation.CHEMINFORM, Issue 29 2005Iliyas A. Sayyed Abstract For Abstract see ChemInform Abstract in Full Text. [source] Osmylated Macroporous Cinchona Alkaloid Resins: Highly Efficient and Recyclable Catalysts for Asymmetric Dihydroxylation of Olefins.CHEMINFORM, Issue 13 2005Yil Sung Park Abstract For Abstract see ChemInform Abstract in Full Text. [source] Asymmetric Synthesis of Cyclic Hydroxy Ketones Derived from Enol Ethers via Sharpless Asymmetric Dihydroxylation.CHEMINFORM, Issue 9 2004A Study in the Correlation of the Enol Ether Chain Length, Enantioselectivity. Abstract For Abstract see ChemInform Abstract in Full Text. [source] Osmium Tetroxide in Poly(ethylene glycol) (PEG): A Recyclable Reaction Medium for Rapid Asymmetric Dihydroxylation under Sharpless Conditions.CHEMINFORM, Issue 43 2003S. Chandrasekhar Abstract For Abstract see ChemInform Abstract in Full Text. [source] On the Origin of the Facial Selectivity of the Sharpless Asymmetric Dihydroxylation of Styrene Derivatives.CHEMINFORM, Issue 26 2003Nicolas Moitessier Abstract For Abstract see ChemInform Abstract in Full Text. [source] Asymmetric Dihydroxylation of Heteroaromatic Acrylates.CHEMINFORM, Issue 15 2003Zhi-Xiang Feng Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Mechanistically Designed Cinchona Alkaloid Ligand in the Osmium Catalyzed Asymmetric Dihydroxylation of Alkenes.CHEMINFORM, Issue 39 2002B. B. Lohray Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Asymmetric Dihydroxylation of Olefins Using Cinchona Alkaloids on Highly Ordered Inorganic Supports.CHEMINFORM, Issue 46 2001Irina Motorina Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Asymmetric Dihydroxylation of trans-Cinnamates under High-Pressure Conditions: Substantial Increase of Turnover Number.CHEMINFORM, Issue 46 2001Choong Eui Song Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Sharpless Asymmetric Dihydroxylation of Olefins in WaterSurfactant Media with Recycling of the Catalytic System by Membrane NanofiltrationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2008Abstract This paper presents a new and more sustainable alternative approach for the Sharpless catalytic asymmetric dihydroxylation (AD) of olefins using a water/surfactant system as reaction media. The AD reaction was performed using several cationic and anionic surfactants allowing yields and enantiomeric excesses higher or comparable with the conventional systems (using organic mixtures). The use of this water/surfactant medium offers the additional advantage of performing the reactions without the need of a slow addition of olefins. Asymmetric dihydroxylation of 1-hexene in a 1.5,mM sodium cholate aqueous solution, using N -methylmorpholine N -oxide (NMO) as co-oxidant was selected as model system to evaluate the feasibility of recycling the Sharpless catalytic system by nanofiltration. The reaction media was processed by nanofiltration, the product was isolated in the permeate, whereas the catalytic system and surfactant were retained by the membrane and recycled through six successive reactions, improving the catalyst turn-over number. The experimental results were compared with the ones calculated on the basis of mass balances, membrane rejections to product and reaction yields. [source] An Efficient Total Synthesis of Decarestrictine D,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 7 2008Priti Gupta Abstract An efficient total synthesis of decarestrictine D has been achieved using cross-metathesis or ring-closing metathesis and Yamaguchi macrolactonization as key steps. The stereogenic centres were generated by means of hydrolytic kinetic resolution (HKR) and Sharpless asymmetric dihydroxylation (AD). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Efficient Total Synthesis of (,)-(3S,6R)-3,6-Dihydroxy-10-methylundecanoic AcidEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2007Satyendra Kumar Pandey Abstract An efficient enantioselective synthesis of (,)-(3S,6R)-3,6-dihydroxy-10-methylundecanoic acid (1) from epichlorohydrin is described. The key steps include Jacobsen's HKR, Sharpless asymmetric dihydroxylation, regioselective opening of epoxide and cyclic sulfate. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Enantioselective Butenolide Preparation for Straightforward Asymmetric Syntheses of ,-Lactones , Paraconic Acids, Avenaciolide, and Hydroxylated EleutherolEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2006Stefan Braukmüller Abstract The naturally occurring ,-lactones (+)-methylenolactocin (13) and its enantiomer, (+)-protolichesterinic acid (14) and its enantiomer, (+)-rocellaric acid (15), and the methylene bis(,-lactone) (,)-avenaciolide (16) were synthesized with 95,98,% ees in very few steps. Enantiocontrol was imposed by the asymmetric dihydroxylation of trans -configured ,,,-unsaturated carboxylic esters (namely compounds 1i, 1j, and 1n) with AD mix-,® [for the levorotatory target structures, except for (,)-avenaciolide] or AD mix-,® [for the dextrorotatory target structures plus (,)-avenaciolide]. ,,,-Unsaturated carboxylic ester 1e required increased amounts of the oxidant and auxiliary to produce the hydroxy lactone R,R - 3e, a precursor of the naphtho-,-lactone (+)-9-hydroxyeleutherol (12; 96,% ee). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Asymmetric Dihydroxylation of ,,,-Unsaturated Carboxylic Esterswith Trisubstituted C=C Bonds , Enantioselective Syntheses of Trisubstituted ,-ButyrolactonesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2006Tobias Kapferer Abstract ,,,-Unsaturated esters with stereodefined trisubstitued C=C double bonds were prepared by the Arndt,Eistert homologation of ,,,-unsaturated carboxyl halides, by two-step methoxycarbonylation of allylbarium reagents, by deconjugation of ,,,-unsaturated esters, and by Horner,Wadsworth,Emmons variants of the Stobbe condensation. Sharpless asymmetric dihydroxylation of the ,,,-unsaturated esters, followed by spontaneous cyclization, afforded ,-hydroxy-,-lactones in moderate to good yields and with enantiomeric excesses of up to 97,%. Similarly, tetrahydroxy-,-lactones were obtained from diunsaturated esters; these lactones were converted into a bislactone and an unsaturated ,-hydroxy ,-lactone. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] A Symmetry-Based Synthesis of the Heterobicyclic Core of the Zaragozic Acids/SqualestatinsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009Yuzhou Wang Abstract The pseudo C2 -symmetrical diketone 22 was efficiently constructed from furan-3,4-dimethanol (7) using a two-directional route featuring a double asymmetric dihydroxylation. Acidic hydrolysis of the cyclopentylidene acetals of 22 triggered a selective cyclization of the resulting hexaol diketone to generate the 2,8-dioxabicyclo[3.2.1]octane core of the zaragozic acids/squalestatins. Chemoselective oxidative cleavage of a superfluous two-carbon appendage and further functional group manipulations yielded the enantiomerically pure triester 30, which offers itself as a general heterobicyclic building block for naturally occurring zaragozic acids/squalestatins and unnatural analogues. [source] Total Synthesis of (+)-RutamarinADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2008Yi-Nan Zhang Abstract The first enantioselective total synthesis of (+)-rutamarin (1) is described. The synthetic route features the highly enantioselective construction of the stereogenic center via the Sharpless asymmetric dihydroxylation (99% ee), the facile assembly of quaternary carbon-centered 3-substituted side chain and high synthetic efficiency from readily available starting materials. Furthermore, the synthetic strategy could be readily adopted for the synthesis of (+)-rutamarin analogues. [source] Sharpless Asymmetric Dihydroxylation of Olefins in WaterSurfactant Media with Recycling of the Catalytic System by Membrane NanofiltrationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2008Abstract This paper presents a new and more sustainable alternative approach for the Sharpless catalytic asymmetric dihydroxylation (AD) of olefins using a water/surfactant system as reaction media. The AD reaction was performed using several cationic and anionic surfactants allowing yields and enantiomeric excesses higher or comparable with the conventional systems (using organic mixtures). The use of this water/surfactant medium offers the additional advantage of performing the reactions without the need of a slow addition of olefins. Asymmetric dihydroxylation of 1-hexene in a 1.5,mM sodium cholate aqueous solution, using N -methylmorpholine N -oxide (NMO) as co-oxidant was selected as model system to evaluate the feasibility of recycling the Sharpless catalytic system by nanofiltration. The reaction media was processed by nanofiltration, the product was isolated in the permeate, whereas the catalytic system and surfactant were retained by the membrane and recycled through six successive reactions, improving the catalyst turn-over number. The experimental results were compared with the ones calculated on the basis of mass balances, membrane rejections to product and reaction yields. [source] Preparation, Characterization and Catalytic Properties of Polyaniline-Supported Metal ComplexesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 12-13 2006Boyapati Abstract Polyaniline-supported Sc, In, Pd, Os and Re catalysts were prepared by using a simple protocol and the thus prepared catalysts were well characterized using FTIR, XPS, UV-Vis/DRS, TGA-DTA. All the catalysts were successfully employed in a wide range of organic transformations such as cyanation and allylation of carbonyl compound, Suzuki coupling of aryl halides and boronic acids, and, most importantly, in asymmetric dihydroxylation of olefins to afford optically active vicinal diols. All the catalysts were separated from the reaction mixture by simple filtration and reused with consistent activity for five cycles without noticeable leaching of metal from the support. [source] A Novel Microencapsulated Osmium Catalyst Using Cross-Linked Polystyrene as an Efficient Catalyst for Asymmetric Dihydroxylation of Olefins in WaterADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2005Tasuku Ishida Abstract A novel microencapsulated osmium catalyst (PSresin-MC Os) was developed using cross-linked polystyrene. The concept of this method may go beyond that of microencapsulation. The catalyst was successfully used in asymmetric dihydroxylation in water, and it was recovered quantitatively by simple filtration and reused several times without loss of activity. The shape of the catalyst was maintained even after several uses. Moreover, no leaching of the Os component was detected. [source] Biocatalytic Asymmetric Dihydroxylation of Conjugated Mono- and Poly-alkenes to Yield Enantiopure Cyclic cis -DiolsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2005Derek Abstract Dioxygenase-catalysed asymmetric dihydroxylation, of a series of conjugated monoalkenes and polyenes, was found to yield the corresponding monols and 1,2-dihydrodiols. The diol metabolites were obtained from monosubstituted, gem -disubstituted, cis -disubstituted, and trisubstituted alkene substrates, using whole cells of Pseudomonas putida strains containing toluene and naphthalene dioxygenases. Dioxygenase selection and alkene type were established as important factors, in the preference for dioxygenase-catalysed 1,2-dihydroxylation of conjugated alkene or arene groups, and monohydroxylation at benzylic or allylic centres. Competition from allylic hydroxylation of methyl groups was observed only when naphthalene dioxygenase was used as biocatalyst. The structures, enantiomeric excess values and absolute configurations of the bioproducts, were determined by a combination of stereochemical correlation, spectroscopy (NMR and CD) and X-ray diffraction methods. cis -1,2-Diol metabolites from arenes, cyclic alkenes and dienes were generally observed to be enantiopure (>98% ee), while 1,2-diols from acyclic alkenes had lower enantiomeric excess values (<88% ee). The enantiopure cis -diol metabolite of a gem -disubstituted fulvene was used as precursor in a new chemoenzymatic route to a novel C2 -symmetrical ketone. [source] Enantioselective separation of chiral vicinal diols in capillary electrophoresis using a mono-6A -aminoethylamino-,-cyclodextrin as a chiral selectorJOURNAL OF SEPARATION SCIENCE, JSS, Issue 1 2009Peng Liu Abstract This paper describes an improved access to mono-6A -aminoethylamino-,-CD (,-CDen), a very efficient cationic chiral selector for CZE in the separation of eight chiral aromatic vicinal diols. The ,-CDen concentration has a strong influence on the efficiency of enantioseparation. The effects of the pH and concentration of the BGE, the capillary temperature, and the applied voltage on the resolution and separation selectivity have been studied. Excellent chiral resolution was achieved under the optimal conditions of ,-CDen 10 mM, pH 10, 200 mM borate buffer at 15 kV and 20°C within 20 min. Moreover, the developed method was successfully applied to the determination of the enantiomeric purity of the catalytic asymmetric dihydroxylation (AD) reaction products. [source] Vinyl sulfones: Synthetic preparations and medicinal chemistry applicationsMEDICINAL RESEARCH REVIEWS, Issue 6 2006D. Christopher Meadows Abstract Vinyl sulfones have long been known for their synthetic utility in organic chemistry, easily participating in 1,4-addition reactions and cycloaddition reactions. This functional group has also recently been shown to potently inhibit a variety of enzymatic processes providing unique properties for drug design and medicinal chemistry. This review includes traditional methods used for the synthesis of vinyl sulfones, but focuses mainly on newer reactions applied to vinyl sulfones, including olefin metathesis, conjugate reduction, asymmetric dihydroxylation (AD), and the use of vinyl sulfones to arrive at highly functionalized targets, all illustrating the rich and versatile chemistry this group can efficiently perform. In addition, geminal disulfones are discussed with respect to their formation, reactions, and medicinal applications of this underutilized functional group. © 2006 Wiley Periodicals, Inc. Med Res Rev [source] Enantioselective Dihydroxylation of Alkenes Catalyzed by a PEG-Bound Bi-Cinchona Alkaloid LigandCHINESE JOURNAL OF CHEMISTRY, Issue 1 2005Xi-Wen Yang Abstract The recyclable PEG-bound bi-cinchona alkaloid ligand has been successfully applied to the homogeneous catalytic asymmetric dihydroxylation of various alkenes; good yields and excellent enantioselectivities were obtained. The ligand could be easily recovered and reused for 10 times without any apparent loss of its catalyst efficiency. [source] | ||||||||||