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Allylic Substitution (allylic + substitution)
Kinds of Allylic Substitution Terms modified by Allylic Substitution Selected AbstractsSequential Copper-Catalyzed Rearrangement,Allylic Substitution of Bicyclic Hydrazines with Grignard ReagentsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2009Stefano Crotti Abstract The problem of the synthesis of trans- 1,4-disubstituted hydrazino- and aminocyclopentenes has been resolved by a sequential copper-catalyzed rearrangement,allylic alkylation of 2,3-diazabicyclo[2.2.1]heptenes. The cis -fused 5,5-membered allylic carbazate which is formed in situ by a novel copper(II) triflate [Cu(OTf)2]/(±)-BINAP-catalyzed rearrangement, can be alkylated with a broad spectrum of Grignard reagents with a predominant SN2,-regioselectivity. The N-Boc protecting group proved to be optimal as regards yields, reaction times and regioselectivities. [source] Allylic Substitution versus Suzuki Cross-Coupling: Capitalizing on Chemoselectivity with Bifunctional Substrates,ANGEWANDTE CHEMIE, Issue 10 2010Mahmud Ein Katalysator und zwei Reaktionen: Wenn Palladium die Wahl hat zwischen einem Allylacetat und einem Vinylboronatester, reagiert es bevorzugt mit dem Allylacetat, und es entsteht das Produkt einer allylischen Substitution. In Gegenwart eines Arylbromids und einer Base schließt sich eine Suzuki-Kreuzkupplung zu Allylaminen an (siehe Schema; pin=Pinakol, THF=Tetrahydrofuran). [source] ChemInform Abstract: Iridium-Catalyzed Enantioselective Allylic Substitution of O-Allyl Carbamothioates.CHEMINFORM, Issue 42 2010Qing-Long Xu Abstract Treatment of O-allyl carbamothioates with the Ir catalyst shown in the scheme results in regio- and enantioselective formation of branched S-allyl carbamothioates. [source] ChemInform Abstract: Selective C,S Bond Formation via Fe-Catalyzed Allylic Substitution.CHEMINFORM, Issue 48 2009Markus Jegelka 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] ChemInform Abstract: Copper-Catalyzed Asymmetric Allylic Substitution with Aryl and Ethyl Grignard Reagents.CHEMINFORM, Issue 11 2009Khalid B. Selim 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] ChemInform Abstract: Picolinoxy Group, a New Leaving Group for anti SN2, Selective Allylic Substitution with Aryl Anions Based on Grignard Reagents.CHEMINFORM, Issue 37 2008Yohei Kiyotsuka 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] ChemInform Abstract: Nickel(0) Triethyl Phosphite Complex Catalyzed Allylic Substitution with Retention of Regio- and Stereochemistry.CHEMINFORM, Issue 12 2008Yasutaka Yatsumonji 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] Sequential Catalytic Isomerization and Allylic Substitution.CHEMINFORM, Issue 1 2007Conversion of Racemic Branched Allylic Carbonates to Enantioenriched Allylic Substitution Products. 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] [Rh(CO)2Cl]2 -Catalyzed Domino Reactions Involving Allylic Substitution and Subsequent Carbocyclization Reactions.CHEMINFORM, Issue 37 2005Brandon L. Ashfeld Abstract For Abstract see ChemInform Abstract in Full Text. [source] Polymer-Supported Chiral Phosphinooxazolidine Ligands for Pd-Catalyzed Asymmetric Allylic Substitution.CHEMINFORM, Issue 29 2005Young-Mok Kim Abstract For Abstract see ChemInform Abstract in Full Text. [source] Construction of Chiral Quaternary Carbon Centers by Pd-Catalyzed Asymmetric Allylic Substitution with P,N-1,1,-Ferrocene Ligands.CHEMINFORM, Issue 12 2005Xue-Long Hou Abstract For Abstract see ChemInform Abstract in Full Text. [source] Aziridine-Derived Iminophosphine Ligands in Palladium-Catalyzed Allylic Substitution.CHEMINFORM, Issue 11 2005Shadi Dalili Abstract For Abstract see ChemInform Abstract in Full Text. [source] Novel Synthesis of O-Allylated Oxime Ethers Based on Allylic Substitution with Oximes.CHEMINFORM, Issue 8 2005Hideto Miyabe Abstract For Abstract see ChemInform Abstract in Full Text. [source] Regio- and Diastereoselective Rhodium-Catalyzed Allylic Substitution with Acyclic ,-Alkoxy-Substituted Copper(I) Enolates: Stereodivergent Approach to 2,3,6-Trisubstituted Dihydropyrans.CHEMINFORM, Issue 46 2004P. Andrew Evans No abstract is available for this article. [source] Palladium-Catalyzed Asymmetric Allylic Substitution Using Planar Chiral Hydrazone Ligands.CHEMINFORM, Issue 20 2003Takashi Mino Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis and Screening of New Chiral Ligands for the Copper-Catalyzed Enantioselective Allylic Substitution.CHEMINFORM, Issue 11 2003Sandrine Ongeri Abstract For Abstract see ChemInform Abstract in Full Text. [source] Iridium-Catalyzed Allylic Substitution: Stereochemical Aspects and Isolation of IrIII Complexes Related to the Catalytic Cycle.CHEMINFORM, Issue 4 2003Bjoern Bartels Abstract For Abstract see ChemInform Abstract in Full Text. [source] New Chiral Phosphinoimidazolidine Ligand in Palladium-Catalyzed Asymmetric Allylic Substitution.CHEMINFORM, Issue 52 2002Myung-Jong Jin Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Regioselective Palladium-Catalyzed Electrophilic Allylic Substitution in the Presence of Hexamethylditin.CHEMINFORM, Issue 37 2002Olov A. Wallner 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: Synergy or Competition Between Palladium-Catalysis and KF/Alumina-Mediation for the Allylic Substitution of the Acetates of Baylis,Hillman Adducts by Phenols.CHEMINFORM, Issue 6 2001Olivier Roy 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] A Unified Strategy for the Stereospecific Construction of Propionates and Acetate,Propionates Relying on a Directed Allylic SubstitutionCHEMISTRY - A EUROPEAN JOURNAL, Issue 26 2009Tomislav Reiss Dipl.-Ing. Abstract Flexible friends: A new strategy that relies on o -DPPB-directed allylic substitution has been implemented for the flexible and stereospecific construction of major polyketide and isoprenoid structural elements (see scheme; o -DPPB=ortho -diphenylphosphanyl benzoate; PG=protecting group). [source] Effect of the Leaving Group on the Rate and Mechanism of the Palladium-Catalyzed Isomerization of Cyclic Allylic Benzoates in Allylic SubstitutionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2006Christian Amatore Abstract In chloroform, the reaction of cis -5-phenylcyclohex-2-enyl 4-Z-benzoate (cis - 1Z, Z = NO2, Cl, H, Me, MeO) with Pd0 complexes ligated to PPh3 is reversible and proceeds with isomerization at the allylic position. The rate of isomerization of cis - 1Z to trans - 1Z depends on the catalytic precursor: Pd0(PPh3)4 > {Pd0(dba)2 + 2PPh3} in agreement with an SN2 mechanism in the rate-determining isomerization of the cationic (,3 -allyl)palladium complexes formed in the oxidative addition. For a given precursor, the rate of isomerization of cis - 1Z to trans - 1Z also depends on the substituent Z, i.e., on the leaving group. The isomerization rate follows the same order as the leaving group properties: 4-NO2,C6H4 -CO2,> 4-Cl,C6H4 -CO2, > C6H5 -CO2, > 4-Me,C6H4 -CO2, > 4-MeO,C6H4 -CO2,. The same tendency is found for the equilibrium constant between the neutral cis - 1Z and the cationic (,3 -allyl)palladium complex in DMF. The higher the concentration of the cationic (,3 -allyl)palladium complex, the faster the isomerization of cis - 1Z to trans - 1Z is. The isomerization of cis - 1Z to trans - 1Z and that of the cationic (,3 -allyl)palladium complexes are at the origin of the lack of stereospecificity observed in catalytic nucleophilic allylic substitutions. These isomerizations are affected by both the leaving groups and the Pd0 precursors, which therefore are not "innocent" but may play an important role in palladium-catalyzed nucleophilic substitutions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Better Performance of Monodentate P -Stereogenic Phosphanes Compared to Bidentate Analogues in Pd-Catalyzed Asymmetric Allylic AlkylationsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2010Arnald Grabulosa Abstract The cationic allylpalladium complexes 3a,3f, 4a, 4e, 5e of type [Pd(,3 -2-Me-C3H4)P2]PF6 were synthesized using a group of monodentate P -stereogenic phosphanes, P=PPhRR, (a,f) and diphosphanes (PhRPCH2)2 (1a, 1e) or PhRPCH2Si(Me)2CH2PPhR (2e). The analogous cationic complexes with the disubstituted allyl group (,3 -1,3-Ph2 -C3H3) and monodentate phosphanes were not isolated as stable solids; only [PdCl(,3 -1,3-Ph2 -C3H3)P] (6a, 6d) were obtained. Palladium allyl complexes were screened as precatalysts in the allylic substitution of rac -3-acetoxy-1,3-diphenyl-1-propene (I) and (E)-3-acetoxy-1-phenyl-1-propene (III) with dimethyl malonate as the nucleophile. The various catalytic precursors showed a wide range of activity and selectivity. The bismonodentate phosphane complexes 3 are more active than the bidentate analogues. With regard to the regioselectivity, precursors containing monodentate phosphanes favour the formation of the linear product in the allylic substitution of cinnamyl acetate (III) compared with those containing bidentate phosphanes. With substrate I, compounds with the diphosphanes 1a and 1e, containing a five-membered chelate ring, gave low enantioselectivities (less than 10,% ee), but those with the diphosphane 2e, forming a six-membered chelate ring or with two monodentate phosphanes, afforded products with moderate enantioselectivity under standard conditions (ee up to 74,%). The results show that the performance of precursors containing monodentate phosphanes was superior to those containing bidentate ligands in both activity and selectivity. [source] Norbornene Bidentate Ligands: Coordination Chemistry and Enantioselective Catalytic ApplicationsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 5 2010Fernando Fernández Abstract N - and P-donor derivatives have been prepared by functionalization of a readily available norbornene precursor. Palladium catalytic systems containing these new ligands were applied in allylic substitution, and yielded high activities and excellent enantioselectivities for the allylic alkylation and amination reactions (ee up to 97,%). A full coordination analysis of the catalytic precursors including modelling studies was also carried out. [source] Enantioselective Copper-Catalysed Allylic Alkylation of Cinnamyl Chlorides by Grignard Reagents using Chiral Phosphine-Phosphite LigandsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010Wibke Lölsberg Abstract The copper(I)-catalysed SN2,-type allylic substitution of E -3-aryl-allyl chlorides (cinnamyl chlorides) using Grignard reagents represents a powerful method for the synthesis of compounds carrying a benzylic stereocentre. By screening a small library of modular chiral phosphine-phosphite ligands a new copper(I)-based catalyst system was identified which allows the performance of such reactions with exceptional high degrees of regio- and enantioselectivity. Best results were obtained using TADDOL-derived ligands (3,mol%), copper(I) bromide,dimethyl sulfide (CuBr,SMe2) (2.5,mol%) and methyl tert -butyl ether (MTBE) as a solvent. Various (1-alkyl-allyl)benzene derivatives were prepared with up to 99% ee (GC) in isolated yields of up to 99%. In most cases the product contained less than 3% of the linear regioisomer (except for ortho -substituted substrates). Both electron-rich and electron-deficient cinnamyl chlorides were successfully employed. The absolute configuration of the products was assigned by comparison of experimental and calculated CD spectra. The substrates were prepared from the corresponding alcohols by reaction with thionyl chloride. Initially formed mixtures of regioisomeric allylic chlorides were homogenised by treatment with CuBr,SMe2 (2.5,mol%) in the presence of triphenyl phosphine (PPh3) (3,mol%) in MTBE at low temperature to give the pure linear isomers. In reactions with methylmagnesium bromide (MeMgBr) an ortho -diphenylphosphanyl-arylphosphite ligand with an additional phenyl substituent in ortho, -position at the aryl backbone proved to be superior. In contrast, best results were obtained in the case of higher alkyl Grignard reagents (such as ethyl-, n -butyl-, isopropyl-, and 3-butenylmagnesium bromides) with a related ligand carrying an isopropyl substituent in ortho, -position. The method was tested on a multi-mmol scale and is suited for application in natural product synthesis. [source] A Combinatorial Approach to Heterogeneous Asymmetric Aquacatalysis with Amphiphilic Polymer-Supported Chiral Phosphine-Palladium ComplexesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 12-13 2006Yukinari Kobayashi Abstract A library of amphiphlic polystyrene-poly(ethylene glycol) (PS-PEG) resin-supported chiral phosphine ligands was prepared by the split method using porous miniature reactors. A polymeric (R)-2-(diphenylphosphino)binaphthyl (MOP) ligand anchored onto the PS-PEG resin by an (S)-alanine tether unit was identified through the library-based screening to be an effective chiral ligand for the asymmetric palladium-catalyzed ,-allylic substitution under heterogeneous aqueous conditions. [source] New Carbohydrate-Based Phosphite-Oxazoline Ligands as Highly Versatile Ligands for Palladium-Catalyzed Allylic Substitution ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 15 2005Yvette Mata Abstract We have designed and synthesized a new family of readily available phosphite-oxazoline ligands for Pd-catalyzed asymmetric allylic substitution reactions. These ligands can be tuned in two regions to explore their effect on catalytic performance. By carefully selecting the ligand components, we obtained high enantioselectivities in the Pd-catalyzed allylic substitution in substrates with different steric properties [source] Modular Furanoside Diphosphite Ligands for Pd-Catalyzed Asymmetric Allylic Substitution Reactions: Scope and LimitationsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2005Montserrat Diéguez Abstract We have synthesized a library of furanoside diphosphite ligands for the Pd-catalyzed allylic substitution reactions of acyclic and cyclic allylic esters. The library has been designed to rapidly screen the ligands to uncover their important structural features and to determine the scope of diphosphite ligands in these catalytic reactions. After the systematic variation of the sugar backbone, the substituent at C-5 and the phosphite moieties, the diphosphite ligand 4c was found to be optimal in the Pd-catalyzed asymmetric allylic substitution of hindered (S1) and unhindered (S2,S5) substrates, yielding high activities [TOFs up to >3000,mol×(mol×h),1] and enantioselectivities (ees up to 99%). In addition, the screening of the library enabled us to find other suitable ligands for hindered disubstituted linear substrate S1 (ligands 1b,d, g and 4b, d, g) and for unhindered cyclic substrates S3,S5 (ligands 6c and 7c). [source] A Unified Strategy for the Stereospecific Construction of Propionates and Acetate,Propionates Relying on a Directed Allylic SubstitutionCHEMISTRY - A EUROPEAN JOURNAL, Issue 26 2009Tomislav Reiss Dipl.-Ing. Abstract Flexible friends: A new strategy that relies on o -DPPB-directed allylic substitution has been implemented for the flexible and stereospecific construction of major polyketide and isoprenoid structural elements (see scheme; o -DPPB=ortho -diphenylphosphanyl benzoate; PG=protecting group). [source] Novel chiral sulfur-containing ferrocenyl ligands for palladium-catalyzed asymmetric allylic substitutionCHIRALITY, Issue 1 2004Shuichi Nakamura Abstract New chiral ferrocenyl ligands having chiral sulfinyl and phosphinyl groups were prepared. The palladium-catalyzed allylic substitution reaction using these chiral ligands showed good enantioselectivity. The mechanism for the asymmetric reaction is proposed on the basis of the stereochemical outcome. Chirality 16:10,12, 2004. © 2003 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||