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Allylic Chlorides (allylic + chloride)
Selected AbstractsChemInform Abstract: Cyclopropylmethylation of Benzylic and Allylic Chlorides with Cyclopropylmethylstannane Catalyzed by Gallium or Indium Halide.CHEMINFORM, Issue 31 2010Kensuke Kiyokawa 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] Palladium(II)-Catalyzed Domino Reaction of 2-(1-Alkynyl)-2-alken-1-ones with Nucleophiles: Scope, Mechanism and Synthetic Application in the Synthesis of 3,4-Fused Bicyclic Tetrasubstituted FuransADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2009Yuanjing Xiao Abstract Described herein is the development of a palladium(II)-catalyzed two- or three-component reaction of 2-(1-alkynyl)-2-alken-1-ones with nucleophiles and allylic chlorides. Various types of nucleophiles such as O- , N- , C -based nucleophiles and olefin-tethered O- , N- , C -based nucleophiles were investigated. The scope, mechanism and application of this Pd(II)-catalyzed domino reaction were studied. In these transformations, the palladium catalyst exhibits a dual role, serving simultaneously as a Lewis acid and a transition metal. Two possible reaction pathways (cross-coupling reaction vs. Heck reaction) from the same intermediate furanylpalladium species were observed. The reaction pathway is dependent on the property of the nucleophile and the length of the tethered chain as well. When olefin-tethered O -based nucleophiles were used, only the cross-coupling reaction pathway was observed, in contrast, both reaction pathways were observed when olefin-tethered C -based nucleophiles were employed. The product ratio is dependent on the length of the tethered chain. Furthermore, ring-closing metathesis (RCM) of corresponding furans with CC bonds provides an easy method for the preparation of functionalized oxygen-heterocycles , 3,4-fused bicyclic furans. It is also noteworthy that allylic chloride can be as an oxidant besides its well known function as an alkylating reagent. [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] Palladium(II)-Catalyzed Domino Reaction of 2-(1-Alkynyl)-2-alken-1-ones with Nucleophiles: Scope, Mechanism and Synthetic Application in the Synthesis of 3,4-Fused Bicyclic Tetrasubstituted FuransADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2009Yuanjing Xiao Abstract Described herein is the development of a palladium(II)-catalyzed two- or three-component reaction of 2-(1-alkynyl)-2-alken-1-ones with nucleophiles and allylic chlorides. Various types of nucleophiles such as O- , N- , C -based nucleophiles and olefin-tethered O- , N- , C -based nucleophiles were investigated. The scope, mechanism and application of this Pd(II)-catalyzed domino reaction were studied. In these transformations, the palladium catalyst exhibits a dual role, serving simultaneously as a Lewis acid and a transition metal. Two possible reaction pathways (cross-coupling reaction vs. Heck reaction) from the same intermediate furanylpalladium species were observed. The reaction pathway is dependent on the property of the nucleophile and the length of the tethered chain as well. When olefin-tethered O -based nucleophiles were used, only the cross-coupling reaction pathway was observed, in contrast, both reaction pathways were observed when olefin-tethered C -based nucleophiles were employed. The product ratio is dependent on the length of the tethered chain. Furthermore, ring-closing metathesis (RCM) of corresponding furans with CC bonds provides an easy method for the preparation of functionalized oxygen-heterocycles , 3,4-fused bicyclic furans. It is also noteworthy that allylic chloride can be as an oxidant besides its well known function as an alkylating reagent. [source] | ||||||||||