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Mukaiyama Aldol Reaction (mukaiyama + aldol_reaction)
Selected AbstractsBismuth Triflate Catalyzed Mukaiyama Aldol Reaction in an Ionic LiquidEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2005Thierry Ollevier Abstract We have developed an efficient, bismuth triflate catalyzed Mukaiyama aldol reaction. The reaction proceeds rapidly and affords the corresponding ,-hydroxy carbonyl compound in moderate to very good yields (up to 92,%). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Organocatalyzed Highly Enantioselective and anti -Selective Construction of ,-Butenolides through Vinylogous Mukaiyama Aldol ReactionADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 8 2010Ning Zhu Abstract The formation of chiral ,-butenolides has been achieved with good yields (up to 90%), high enantioselectivity (up to 91%) and diastereoselectivity (up to 9/1, anti -selective) through an organocatalyzed vinylogous Mukaiyama aldol reaction of 2-(trimethylsilyloxy)furan and aldehydes. A wide range of chiral ,-butenolides was obtained under mild conditions by this methodology. [source] Efficient Heterogeneous Asymmetric Catalysis of the Mukaiyama Aldol Reaction by Silica- and Ionic Liquid-Supported Lewis Acid Copper(II) Complexes of Bis(oxazolines)ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2 2008S. Doherty Abstract Lewis acid complexes based on copper(II) and an imidazolium-tagged bis(oxazoline) have been used to catalyse the asymmetric Mukaiyama aldol reaction between methyl pyruvate and 1-methoxy-1-trimethylsilyloxypropene under homogeneous and heterogeneous conditions. Although the ees obtained in ionic liquid were similar to those found in dichloromethane, there was a significant rate enhancement in the ionic liquid with reactions typically reaching completion within 2,min compared with only 55,% conversion after 60,min in dichloromethane. However, this rate enhancement was offset by lower chemoselectivity in ionic liquids due to the formation of 3-hydroxy-1,3-diphenylbutan-1-one as a by-product. Supporting the catalyst on silica or an imidazolium-modified silica using the ionic liquid or in an ionic liquid-diethyl ether system completely suppressed the formation of this by-product without reducing the enantioselectivity. Although the heterogeneous systems were characterised by a drop in catalytic activity the system could be recycled up to five times without any loss in conversion or ee. [source] ChemInform Abstract: New Indenyl Phosphinooxazoline Complexes of Iron and Their Catalytic Activity in the Mukaiyama Aldol Reaction.CHEMINFORM, Issue 35 2010Matthew Lenze Abstract It is demonstrated that a new iron-indenyl PHOX complex is efficient for the title reaction of the 1-siloxy 1-methoxyethene with aromatic aldehydes. [source] A Tandem Enol Silane Formation,Mukaiyama Aldol Reaction Mediated by TMSOTf.CHEMINFORM, Issue 35 2007C. Wade Downey 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] Hydrogen Bond Catalyzed Enantioselective Vinylogous Mukaiyama Aldol Reaction.CHEMINFORM, Issue 18 2006Vijaya Bhasker Gondi 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] Highly Enantioselective Mukaiyama Aldol Reaction of ,,,-Dichloro Ketene Silyl Acetal: An Efficient Synthesis of a Key Intermediate for Diltiazem.CHEMINFORM, Issue 25 2003Ritsuo Imashiro Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Scope and Limitations of Chiral B-[3,5-Bis(trifluoromethyl)phenyl]oxazaborolidine Catalyst for Use in the Mukaiyama Aldol Reaction.CHEMINFORM, Issue 19 2001Kazuaki Ishihara 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] Catalytic, Asymmetric Vinylogous Mukaiyama Aldol Reactions of Pyrrole- and Furan-Based Dienoxy Silanes: How the Diene Heteroatom Impacts StereocontrolADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010Claudio Curti Abstract Denmark's chiral bisphosphoramide/silicon tetrachloride system performs as an excellent Lewis base-Lewis acid catalyst for the vinylogous Mukaiyama aldol reaction of pyrrole- and furan-based dienoxy silanes with aromatic and heteroaromatic aldehydes. This asymmetric methodology provides a powerful synthetic entry to a variety of ,-hydroxylated ,-butenolide-type frameworks with high efficiency and valuable margins of regio-, diastereo-, and enantioselectivity. Notably, the nature of the heteroatom within the vinylogous dienoxy silane donor heavily impacts the diastereocontrol, with syn -configured aldol adducts emerging from pyrroles bearing electron-withdrawing N -protecting groups (Boc, Ts, and Cbz) and anti -configured adducts prevailing when furan- or N -alkyl/alkenylpyrrole donors are involved. [source] Bismuth Triflate Catalyzed Mukaiyama Aldol Reaction in an Ionic LiquidEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2005Thierry Ollevier Abstract We have developed an efficient, bismuth triflate catalyzed Mukaiyama aldol reaction. The reaction proceeds rapidly and affords the corresponding ,-hydroxy carbonyl compound in moderate to very good yields (up to 92,%). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Catalytic, Asymmetric Vinylogous Mukaiyama Aldol Reactions of Pyrrole- and Furan-Based Dienoxy Silanes: How the Diene Heteroatom Impacts StereocontrolADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010Claudio Curti Abstract Denmark's chiral bisphosphoramide/silicon tetrachloride system performs as an excellent Lewis base-Lewis acid catalyst for the vinylogous Mukaiyama aldol reaction of pyrrole- and furan-based dienoxy silanes with aromatic and heteroaromatic aldehydes. This asymmetric methodology provides a powerful synthetic entry to a variety of ,-hydroxylated ,-butenolide-type frameworks with high efficiency and valuable margins of regio-, diastereo-, and enantioselectivity. Notably, the nature of the heteroatom within the vinylogous dienoxy silane donor heavily impacts the diastereocontrol, with syn -configured aldol adducts emerging from pyrroles bearing electron-withdrawing N -protecting groups (Boc, Ts, and Cbz) and anti -configured adducts prevailing when furan- or N -alkyl/alkenylpyrrole donors are involved. [source] Fluorous Surface-Active Distannoxane CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Akihiro Orita Abstract Fluorous distannoxanes (XRf2SnOSnRf2X)2,n,H2O (Rf=C6F13C2H4) (1: X=C8F17SO3, n=10; 4: X=Cl, n=0) (1) catalyze the Mukaiyama aldol reaction and the allylation of aldehydes with tetraallyltin at room temperature in fluorous/organic biphasic solvent systems, in which the reactions proceed more rapidly than in a single organic or fluorous solvent. Due to the unique surface activity of 1, the catalyst, organic substrate(s), and reagent(s) are distributed in both organic and fluorous phases to facilitate smooth reactions. Upon dilution with toluene after the reaction, the catalyst concentrates to the fluorous phase, while the organic substances migrate to the organic phase to effect facile catalyst recovery and recycling. By virtue of such a unique solvophilicity, a new version of fluorous biphase technology has been developed. [source] Organocatalyzed Highly Enantioselective and anti -Selective Construction of ,-Butenolides through Vinylogous Mukaiyama Aldol ReactionADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 8 2010Ning Zhu Abstract The formation of chiral ,-butenolides has been achieved with good yields (up to 90%), high enantioselectivity (up to 91%) and diastereoselectivity (up to 9/1, anti -selective) through an organocatalyzed vinylogous Mukaiyama aldol reaction of 2-(trimethylsilyloxy)furan and aldehydes. A wide range of chiral ,-butenolides was obtained under mild conditions by this methodology. [source] Efficient Heterogeneous Asymmetric Catalysis of the Mukaiyama Aldol Reaction by Silica- and Ionic Liquid-Supported Lewis Acid Copper(II) Complexes of Bis(oxazolines)ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2 2008S. Doherty Abstract Lewis acid complexes based on copper(II) and an imidazolium-tagged bis(oxazoline) have been used to catalyse the asymmetric Mukaiyama aldol reaction between methyl pyruvate and 1-methoxy-1-trimethylsilyloxypropene under homogeneous and heterogeneous conditions. Although the ees obtained in ionic liquid were similar to those found in dichloromethane, there was a significant rate enhancement in the ionic liquid with reactions typically reaching completion within 2,min compared with only 55,% conversion after 60,min in dichloromethane. However, this rate enhancement was offset by lower chemoselectivity in ionic liquids due to the formation of 3-hydroxy-1,3-diphenylbutan-1-one as a by-product. Supporting the catalyst on silica or an imidazolium-modified silica using the ionic liquid or in an ionic liquid-diethyl ether system completely suppressed the formation of this by-product without reducing the enantioselectivity. Although the heterogeneous systems were characterised by a drop in catalytic activity the system could be recycled up to five times without any loss in conversion or ee. [source] Multipurpose box- and azabox-Based Immobilized Chiral CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 12-13 2006Abstract Azabis(oxazolines) can be used as chiral ligands in the copper-catalyzed enantioselective Mukaiyama aldol reaction. When supported on solids, azabis(oxazoline)-copper complexes are more easily deactivated than their analogous bis(oxazoline)-copper complexes, and are not compatible with the use of coordinating solvents in the method of preparation. The performance of the immobilized catalysts (up to 86,% ee) depends on the support and the reaction solvent, with some positive effect on enantioselectivity due to surface effects. The deactivation is not irreversible and the deactivated catalysts show excellent performance in the cyclopropanation reaction, providing added value to the supported multipurpose catalysts. [source] Synthesis and Structure of an Extremely Air-Stable Binuclear Hafnocene Perfluorooctanesulfonate Complex and Its Use in Lewis Acid-Catalyzed ReactionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 26 2009Renhua Qiu Abstract Stable complexes: An extremely air-stable ,2 -hydroxy-bridged binuclear hafonocene perfluorooctanesulfoante complex shows high catalytic efficiency in Lewis acid-catalyzed reactions, such as esterification, Friedel,Crafts acylation, the Mukaiyama aldol reation, and the allylation of aldehyde (see scheme). An extremely air-stable ,2 -hydroxy-bridged binuclear hafonocene perfluorooctanesulfoante complex was successfully synthesized. This complex showed high catalytic efficiency in the esterification of alcohols, phenol, thiol, and amines, in the Friedel,Crafts acylation of alylaryl ethers, in the Mukaiyama aldol reaction, and in the allylation of aldehydes and could be reused. [source] Intramolecular Alkynylogous Mukaiyama Aldol Reaction Starting from Bicyclic Alkanones Tethered to Alkynyl Esters: Formal Total Synthesis of (±)-Hamigeran,BCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2009Laurence Miesch Dr. Abstract Selecting the ring: tert -Butyldimethylsilyltriflate (TBSOTf)/NEt3 treatment of alkynyl esters tethered to bicycloalkanones leads to the formation of tricyclic allenoates with total diasteroselectivity at the ring junction. An intramolecular alkynylogous Mukaiyama aldol reaction promoted by a TBSOTf/NEt3 dual activation is involved. This novel methodology was illustrated by a formal total synthesis of (±)-hamigeran,B. tert -Butyldimethylsilyltriflate (TBSOTf)/NEt3 treatment of alkynyl esters tethered to bicycloalkanones led to tricyclic allenoates with total diastereoselectivity for the ring junction. The allenoates result from an intramolecular alkynylogous Mukaiyama aldol reaction promoted by a TBSOTf/NEt3 dual activation, with key intermediates of silylalkynylketene acetals. This novel methodology was illustrated by a formal total synthesis of (±)-hamigeran,B. [source] | ||||||||||