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Baylis
Selected AbstractsAsymmetric Aza-Morita,Baylis,Hillman Reactions of Alkyl Vinyl Ketones with N -Protected Imines or In Situ Generated N -Protected IminesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2010Xiao-Yang Guan Abstract DABCO-catalyzed aza-MBH reactions of N -Boc imines with MVK and EVK have been thoroughly investigated in the paper. The asymmetric version of this aza-MBH reaction was also systematically investigated by using a chiral amine or a chiral phosphane catalyst. It was found that most of the N -protected imines are suitable substrates under the mild reaction conditions and are able to give the corresponding adducts in moderate yields with high ee values. The TQO- or LB1-catalyzed aza-MBH reactions of N -protected ,-amidoalkyl phenyl sulfones or ,-amidoalkyl p -tolyl sulfones with MVK could be well conducted, which provides a facile and direct route to obtain highly enantioselective aza-MBH adducts. The Boc protecting group of the aza-MBH product could be easily removed under acidic conditions to give the corresponding ,-methylene-,-amino ketone or ,-methylene-,-amino alcohol derivatives in good yields. [source] Stereodefined Access to 3-Deoxy Sugars Through a Tandem Baylis,Hillman and Lewis Acid Catalyzed Reaction SequenceEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2010Palakodety Radha Krishna Abstract An innovative synthetic protocol is reported for the ready access to 3-deoxy sugars in both D and L forms as exclusive products (des >95,%) in high yields through a stereodefined Lewis acid catalyzed reaction sequence of the sugar-derived Baylis,Hillman adducts. [source] Reductive-Cyclization-Mediated Synthesis of Fused Polycyclic Quinolines from Baylis,Hillman Adducts of Acrylonitrile: Scope and Limitations,,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2009Virender Singh Abstract The synthesis of a variety of polycyclic quinolines is described. The target molecules were obtained in two steps by an initial reductive cyclization followed by another intramolecular cyclization in the allylamines afforded from either the acetates or allyl bromides of Baylis,Hillman adducts of 2-nitrobenzaldehydes and acrylonitrile. The two steps proceeded in one-pot for those substrates in which a formyl or hydroxy group reacted with the amino group of the 2-aminoquinoline in the second intramolecular cyclization. In contrast, a basic medium was necessary for the second intramolecular cyclization reaction in substrates in which an alkoxycarbonyl group and the amino group participated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Mapping the Mechanism of Nickel-Ferrophite Catalysed Methylation of Baylis,Hillman-Derived SN2, ElectrophilesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2009Andrew Novak Abstract Enantioselective Ni-catalysed methylation of Baylis,Hillman-derived allylic electrophiles in the presence of ferrophite ligands has been investigated computationally and experimentally. The sense and degree of enantioselectivity attained is independent of both the leaving group and the isomeric structure of the initial allylic halide. DFT studies support the selective formation of a limited number of energetically favoured anti and syn ,-allyl intermediates. The observed regio- and enantioselectivity can be rationalised based on the energetics of these structures. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Straightforward Strategy for the Stereoselective Synthesis of Spiro-Fused (C-5)Isoxazolino- or (C-3)Pyrazolino-(C-3)quinolin-2-ones from Baylis,Hillman Adducts by 1,3-Dipolar Cycloaddition and Reductive Cyclization,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 32 2008Virender Singh Abstract A straightforward and general approach for the stereoselective synthesis of spiro-fused (C-5)isoxazolino- or (C-3)pyrazolino-(C-3)quinolin-2-ones from the adducts offorded from the Baylis,Hillman reaction of 2-nitrobenzaldehyde and ethyl acrylate by sequential 1,3-dipolar cycloaddition and reductive cyclization is presented. It was found that the reductive cyclization of the isoxazoline derivatives proceeded efficiently in the presence of In/HCl, whereas similar reductions of pyrazolines gave better yields when carried out in the presence of an Fe/AcOH mixture. However, similar attempts employing the Baylis,Hillman adduct of 2-nitrobenzaldehyde and methyl vinyl ketone did not yield the desired compounds.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis of Substituted 1H - and 3H -1-Benzazepines and Rearrangement of Alkyl 1H -1-Benzazepine-2-carboxylates into Isoquinolines,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2007Vijay Singh Abstract The SnCl2 -mediated reduction of nitro groups in 2-nitro-4-(2-nitrobenzylidene)alkanoates and 4-nitro-2-(2-nitroalkylidene)alkanoates allows the facile synthesis of substituted 1H -1-benzazepines and 3H -1-benzazepines. This reaction proceeds via SN2, reaction of ethyl nitroacetate and nitroethane with the acetyl derivatives of Baylis,Hillman adducts deriving from 2-nitro-substituted benzaldehydes. During the study, an unprecedented rearrangement of an alkyl 1H -benzazepine-2-carboxylate to a substituted isoquinoline has been observed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] The First Enantioselective Halo Aldol Reaction of Ethyl Propiolate and AldehydesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 15 2004Dianjun Chen Abstract The first enantioselective halo aldol reaction of ethyl propiolate with aldehydes has been established by using Jacobsen's chiral cyclohexylsalen ligand. The reaction was conducted at ,20 °C in dichloromethane with Et2AlI as the source of halogen and Lewis acid promoter. Excellent geometric selectivity (only the Z isomer) has been achieved for all 14 examples examined. The reaction works well with aromatic aldehydes; it also works with aliphatic aldehydes and ,,,-unsaturated aldehydes, albeit with diminished yields and ee. This method provides the first enantioselective synthesis of ,-iodo Morita,Baylis,Hillman (MBH) esters. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] A Rapid and Efficient Stereoselective Synthesis of (Z)- and (E)-Allyl Bromides from Baylis,Hillman Adducts Using Bromo(dimethyl)sulfonium Bromide,HELVETICA CHIMICA ACTA, Issue 7 2006Biswanath Das Abstract Treatment of Baylis,Hillman adducts 1 with bromo(dimethyl)sulfonium bromide, Br(Me2)S+Br,, in MeCN was found to stereoselectively afford (Z)- and (E)-allyl bromides 2. The reaction is rapid at room temperature, high-yielding, and highly stereoselective. [source] Synthesis of cis-Hedione® and Methyl Jasmonate via Cascade Baylis,Hillman Reaction and Claisen Ortho Ester RearrangementHELVETICA CHIMICA ACTA, Issue 12 2005Christian Chapuis The exocyclically unsaturated conjugated keto esters 10, obtained via a Claisen ortho ester rearrangement of the allylic hydroxy ketones 9, were either directly hydrogenated or partially isomerized into the endocyclically unsaturated tetrasubstituted didehydrojasmonoid intermediates 14, prior to a more selective hydrogenation with Pd/C in cyclohexane to the disubstituted oxocyclopentaneacetates 15 (Scheme,2). The key intermediates 9 were obtained either by a four-step sequence, including acetal protection/deprotection from enone 1, in the specific case of hydroxy ketone 9a (Scheme,1), or more directly and generally by a Baylis,Hillman reaction from cyclopent-2-en-1-one (16) and the appropriate aldehydes 17 (Scheme,2). The judicious choice of these aldehydes opens versatile modifications for the stereoselective introduction of the partially cis - or epimerized trans -C(2) jasmonoid side chain, while the Baylis,Hillman reaction, catalyzed by chiral [1,1,-binaphthalene]-2,2,-diols (BINOLs) 19 (Scheme,3), may be efficiently conducted in a one-pot cascade fashion including the ortho ester Claisen rearrangement. [source] A General Approach to the Synthesis of ,2 -Amino Acid Derivatives via Highly Efficient Catalytic Asymmetric Hydrogenation of ,-AminomethylacrylatesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Yujuan Guo Abstract A new strategy was developed for the synthesis of a valuable class of ,-aminomethylacrylates via the Baylis,Hillman reaction of different aldehydes with methyl acrylate followed by acetylation of the resulting allylic alcohols and SN2,-type amination of the allylic acetates. Asymmetric hydrogenation of these diverse olefinic precursors using rhodium(Et-Duphos) catalysts provided the corresponding ,2 -amino acid derivatives with excellent enantioselectivities and exceedingly high reactivities (up to >99.5% ee and S/C=10,000). The first hydrogenation of (Z)-configurated substrates was studied for the synthesis of ,2 -amino acid derivatives. The high influence of the substrate geometry and steric hindrance on the reactivity and enantioselectivity was also disclosed for this reaction. This protocol provides a highly practical, facile and scalable method for the preparation of optically pure ,2 -amino acids and their derivatives under mild reaction conditions. [source] Enantioselective Aza-Morita,Baylis,Hillman Reaction Using Aliphatic ,-Amidosulfones as Imine SurrogatesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2010Nacim Abermil Abstract The bifunctional catalyst 6,-deoxy-6,-acylamino-,-isocupreidine (1) served both as a base to trigger the in situ generation of N -sulfonylimine from readily available ,-amidosulfones and as a chiral nucleophile to initiate the enantioselective aza-Morita,Baylis,Hillman (aza-MBH) reaction. ,-Methylene-,-amino-,-alkyl carbonyl compounds, difficultly accessible previously, can now be synthesized in excellent yields and enantioselectivities. [source] First Copper-Catalyzed Intramolecular Amidation in Substituted 4-Iodopyrazoles Leading to the Synthesis of Pyrazolo[4,3- b]- pyridin-5-ones,ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2009Somnath Nag Abstract An unprecedented copper-catalyzed intramolecular amidation of substituted 4-iodopyrazoles generated either via Baylis,Hillman or Horner,Wadsworth,Emmons chemistry for the synthesis of pyrazolo[4,3- b]pyridine-5-ones is described. In addition, the effect of the stereochemistry of the acrylamide on the cross-coupling reaction has been investigated and it is demonstrated that only the Z-isomer is favoured to undergo the intramolecular cyclization. [source] Cyclic Enones as Substrates in the Morita,Baylis,Hillman Reaction: Surfactant Interactions, Scope and Scalability with an Emphasis on FormaldehydeADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2009Brett Abstract Traditionally, cyclic enones and formalin are reactants notorious for displaying problematic behaviour (i.e., poor solubility and low yields) under Morita,Baylis,Hillman (MBH) reaction conditions. The body of research presented herein focuses on the use of surfactants in water as a solvent medium that offers a resolution to many of the issues associated with the MBH reaction. Reaction scope, scalability and small angle X-ray scattering have been studied to assist with the understanding of the reaction mechanism and industrial application. A comparison against known literature methods for reaction scale-up is also discussed. [source] Enantioselective Trifunctional Organocatalysts for Rate- Enhanced Aza-Morita,Baylis,Hillman Reactions at Room TemperatureADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 3 2009Jean-Marc Garnier Abstract A Brųnsted acid-activated trifunctional organocatalyst, based on the BINAP scaffold, was used for the first time to catalyze aza-Morita-Baylis,Hillman reactions between N -tosylimines and methyl vinyl ketone with fast reaction rates and good enantioselectivity at room temperature. This trifunctional catalyst, containing a Lewis base, a Brųnsted base, and a Brųnsted acid, required acid activation to confer its enantioselectivity and rate improvement for both electron-rich and electron-deficient imine substrates. The role of the amino Lewis base of 1a was investigated and found to be the activity switch in response to an acid additive. The counterion of the acid additive was found to influence not only the excess ratio but also the sense of asymmetric induction. [source] Dendritic Chiral Phosphine Lewis Bases-Catalyzed Asymmetric Aza-Morita,Baylis,Hillman Reaction of N -Sulfonated Imines with Activated OlefinsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1 2008Ying-hao Liu Abstract A series of polyether dendritic chiral phosphine Lewis bases was synthesized, and successfully applied to the asymmetric aza-Morita,Baylis,Hillman reaction of N -sulfonated imines (N -arylmethylidene-4-methylbenzenesulfonamides) with methyl vinyl ketone (MVK), ethyl vinyl ketone (EVK), and acrolein to give the adducts in good to excellent yields along with up to 97,% ee, which are more effective than our previously reported original chiral phosphine Lewis bases. In addition, the dendrimer-supported chiral phosphine Lewis bases can be easily recovered and reused. [source] 1,3,5-Triaza-7-phosphaadamantane (PTA): A Practical and Versatile Nucleophilic Phosphine OrganocatalystADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2007Xiaofang Tang Abstract In this paper, the air-stable and readily available 1,3,5-triaza-7-phosphaadmantane (PTA) is reported as a practical and versatile nucleophilic phosphine organocatalyst. Under the mediation of 15,30 mol,% of PTA, various electrophiles like aldehydes and imines readily undergo the Morita,Baylis,Hillman reactions with a variety of activated olefins, giving the corresponding adducts in high yields. In the phosphine-catalyzed [3+2] cycloaddition reaction of 4-substituted 2,3-butadienoates with N -tosylimines, PTA is also proven to be a comparable catalyst as tributylphosphine (PBu3). By systematic comparison with other structurally similar N,P catalysts, it is concluded that the superiority of PTA in the above nucleophilic catalysis is attributable to its comparable nucleophilicity with that of trialkylphosphines. The feasibility to use PTA as an alternative catalyst in place of the air-sensitive trialkylphosphines is also discussed. [source] Access to Stereodefined Trisubstituted Alkenes via Rhodium-Catalyzed 1,4-Addition of Potassium Trifluoro(organo)- borates to Baylis,Hillman AdductsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 3 2006Laure Navarre Abstract In the presence of a rhodium catalyst, unactivated Baylis,Hillman adducts reacted regioselectively with potassium trifluoro(organo)borates to afford stereodefined trisubstituted alkenes with good yields. This highly efficient reaction (aerobic conditions, low temperature, absence of added phosphane ligand) is believed to proceed via a 1,4-addition/,-hydroxy elimination mechanism. [source] Baylis,Hillman adducts with molluscicidal activity against Biomphalaria glabrataPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 3 2006Mįrio LAA Vasconcellos Abstract The molluscicidal activities of ten Baylis,Hillman adducts against Biomphalaria glabrata (Say) snails, the intermediate host of schistosomiasis, have been determined. Nine of these compounds showed significant molluscicidal activity against B. glabrata, falling below the threshold of 100 µg ml,1 set for potential molluscicidal activity by the World Health Organisation. Among these compounds, 3-hydroxy-2-methylene-3-(4-nitrophenyl)propanenitrile had the highest activity, with LC50 = 6.64 µg ml,1. Copyright © 2006 Society of Chemical Industry [source] Chemoselective Asymmetric N-Allylic Alkylation of Indoles with Morita,Baylis,Hillman Carbonates,ANGEWANDTE CHEMIE, Issue 31 2009Hai-Lei Cui Einfach praktisch: Die Titelreaktion gelingt durch metallfreie Katalyse mit modifizierten Chinaalkaloiden. Mäßige bis ausgezeichnete Enantioselektivitäten wurden für eine Vielzahl an Substraten erreicht (siehe Schema). Die Reaktion bietet zudem einen bequemen Zugang zu mehrfach funktionalisierten Pyrrolo[1,2- a]indol- und Pyrrolo[3,2,1- ij]chinolinderivaten. [source] Novel methodologies for the synthesis of functionalized lipophilic carboranesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 4 2010Subash C. Jonnalagadda Abstract Novel synthetic protocols for the synthesis of lipophilic carboranes were developed utilizing two CC bond forming reactions, namely Baylis,Hillman and enynedioate cycloaddition reactions. Some of these carboranes were converted into further functionalized carboranes via nucleophilic allylic isomerization. Copyright © 2009 John Wiley & Sons, Ltd. [source] Les Sohettes: A model for integrated biorefineriesBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 2 2010Alan BaylisArticle first published online: 19 MAR 2010 With its abundant supply of biomass and its network of farmer cooperatives, companies, universities and research centers, Les Sohettes is a model integrated biorefinery. Alan Baylis takes a closer look and examines what the future holds for the French biorefinery. Copyright © 2010 Society of Chemical Industry and John Wiley & Sons, Ltd [source] ChemInform Abstract: Facile Synthesis of Benzofulvene Derivatives from Baylis,Hillman Adducts: In-Mediated Barbier Reaction Combined with Pd(0)-Catalyzed Intramolecular Heck-Elimination Cascade.CHEMINFORM, Issue 40 2010Ko Hoon Kim Abstract Precursors (V), (VIII), and (XI), derived from Baylis,Hillman adducts via bromination, Barbier reaction with aldehydes and acetylation, are subjected to Pd-catalyzed conditions A) or B). [source] ChemInform Abstract: 3,5-Disubstituted 6H-Pyrrolo[1,2-c][1,2,3]triazoles (VII), (XII) from Morita,Baylis,Hillman Adducts of Propargyl Aldehydes.CHEMINFORM, Issue 39 2010Sun Pil Park No abstract is available for this article. [source] ChemInform Abstract: Direct Asymmetric Allylic Alkylation of Butenolides with Morita,Baylis,Hillman Carbonates.CHEMINFORM, Issue 27 2010Hai-Lei Cui 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: A Convenient Synthesis of 1,5-Diarylpyrazoles from Baylis,Hillman Adducts Using HY-Zeolite.CHEMINFORM, Issue 20 2010Mohammad Nikpassand 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: Valine-Derived Phosphinothiourea as Organocatalyst in Enantioselective Morita,Baylis,Hillman Reactions of Acrylates with Aromatic Aldehydes.CHEMINFORM, Issue 9 2010Jing-Jing Gong 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: Baylis,Hillman Reaction Promoted by a Recyclable Protic,Ionic,Liquid Solvent,Catalyst System: DABCO,AcOH,H2O.CHEMINFORM, Issue 8 2010Ying 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] ChemInform Abstract: Iron(III) Chloride-Catalyzed Direct Nucleophilic ,-Substitution of Morita,Baylis,Hillman Alcohols with Alcohols, Arenes, 1,3-Dicarbonyl Compounds and Thiols.CHEMINFORM, Issue 8 2010Xiaoxiang Zhang 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: Solvent-Free Synthesis of 1,5-Disubstituted Tetrazoles Derived from Baylis,Hillman Acetates as Potential TNF-, Inhibitors.CHEMINFORM, Issue 8 2010P. Srihari 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: Novel DABCO-Catalyzed Regio- and Diastereoselective Nucleophilic Substitution of Baylis,Hillman Acetates with TosMIC.CHEMINFORM, Issue 5 2010Palakodety Radha Krishna 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] | |||||||||||||||||||||||||