Carbonyl-ene Reaction (carbonyl-ene + reaction)

Distribution by Scientific Domains
Chemistry100%

Kinds of Carbonyl-ene Reaction

  • enantioselective carbonyl-ene reaction
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    Selected Abstracts

    Enantioselective Carbonyl-Ene Reaction of Glyoxal Derivatives Catalyzed by Cationic 3-Oxobutylideneaminatocobalt(III) Complexes.

    CHEMINFORM, Issue 16 2003
    Satoko Kezuka
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    Enantioselective Carbonyl-Ene Reactions of Trifluoropyruvate in Ionic Liquid via a Recyclable Indium(III)-Pybox Complex

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010
    Jun Feng Zhao
    Abstract A highly enantioselective carbonyl-ene reaction of trifluoropyruvate catalyzed by a recyclable indium(III)-pybox complex in ionic liquid afforded trifluoromethyl-containing tertiary homoallylic alcohols with excellent yields (up to 98%) and enantioselectivities (up to 98% ee). Notably, this catalytic system can be recycled up to seven cycles. [source]

    Palladium(II) Complexes of C2 -Bridged Chiral Diphosphines: Application to Enantioselective Carbonyl-Ene Reactions

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 8 2010
    He-Kuan Luo
    Abstract (11bR,11,bR)-4,4,-(1,2-Phenylene)bis[4,5-dihydro-3H -dinaphtho[2,1- c:1,,2,- e]phosphepin] [abbreviated as (R)-BINAPHANE], (3R,3,R,4S,4,S,11bS,11,bS)-4,4,-bis(1,1-dimethylethyl)-4,4,,5,5,-tetrahydro-3,3,-bi-3H -dinaphtho[2,1- c:1,,2,- e]phosphepin [(S)-BINAPINE], (1S,1,S,2R,2,R)-1,1,-bis(1,1-dimethylethyl)-2,2,-biphospholane [(S,S,R,R)-TANGPHOS] and (2R,2,R,5R,5,R)-1,1,-(1,2-phenylene)bis[2,5-bis(1-methylethyl)phospholane] [(R,R) -i- Pr-DUPHOS] are C2 -bridged chiral diphosphines that form stable complexes with palladium(II) and platinum(II) containing a five-membered chelate ring. The Pd(II)-BINAPHANE catalyst displayed good to excellent enantioselectivities with ee values as high as 99.0% albeit in low yields for the carbonyl-ene reaction between phenylglyoxal and alkenes. Its Pt(II) counterpart afforded improved yields while retaining satisfactory enantioselectivity. For the carbonyl-ene reaction between ethyl trifluoropyruvate and alkenes, the Pd(II)-BINAPHANE catalyst afforded both good yields and extremely high enantioselectivities with ees as high as 99.6%. A comparative study on the Pd(II) catalysts of the four C2 -bridged chiral diphosphines revealed that Pd(II)-BINAPHANE afforded the best enantioselectivity. The ee values derived from Pd(II)-BINAPHANE are much higher than those derived from the other three Pd(II) catalysts. A comparison of the catalyst structures shows that the Pd(II)-BINAPHANE catalyst is the only one that has two bulky (R)-binaphthyl groups close to the reaction site. Hence it creates a deep chiral space that can efficiently control the reaction behavior in the carbonyl-ene reactions resulting in excellent enantioselectivity. [source]

    Enantioselective Carbonyl-Ene Reactions of Trifluoropyruvate in Ionic Liquid via a Recyclable Indium(III)-Pybox Complex

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010
    Jun Feng Zhao
    Abstract A highly enantioselective carbonyl-ene reaction of trifluoropyruvate catalyzed by a recyclable indium(III)-pybox complex in ionic liquid afforded trifluoromethyl-containing tertiary homoallylic alcohols with excellent yields (up to 98%) and enantioselectivities (up to 98% ee). Notably, this catalytic system can be recycled up to seven cycles. [source]

    Palladium(II) Complexes of C2 -Bridged Chiral Diphosphines: Application to Enantioselective Carbonyl-Ene Reactions

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 8 2010
    He-Kuan Luo
    Abstract (11bR,11,bR)-4,4,-(1,2-Phenylene)bis[4,5-dihydro-3H -dinaphtho[2,1- c:1,,2,- e]phosphepin] [abbreviated as (R)-BINAPHANE], (3R,3,R,4S,4,S,11bS,11,bS)-4,4,-bis(1,1-dimethylethyl)-4,4,,5,5,-tetrahydro-3,3,-bi-3H -dinaphtho[2,1- c:1,,2,- e]phosphepin [(S)-BINAPINE], (1S,1,S,2R,2,R)-1,1,-bis(1,1-dimethylethyl)-2,2,-biphospholane [(S,S,R,R)-TANGPHOS] and (2R,2,R,5R,5,R)-1,1,-(1,2-phenylene)bis[2,5-bis(1-methylethyl)phospholane] [(R,R) -i- Pr-DUPHOS] are C2 -bridged chiral diphosphines that form stable complexes with palladium(II) and platinum(II) containing a five-membered chelate ring. The Pd(II)-BINAPHANE catalyst displayed good to excellent enantioselectivities with ee values as high as 99.0% albeit in low yields for the carbonyl-ene reaction between phenylglyoxal and alkenes. Its Pt(II) counterpart afforded improved yields while retaining satisfactory enantioselectivity. For the carbonyl-ene reaction between ethyl trifluoropyruvate and alkenes, the Pd(II)-BINAPHANE catalyst afforded both good yields and extremely high enantioselectivities with ees as high as 99.6%. A comparative study on the Pd(II) catalysts of the four C2 -bridged chiral diphosphines revealed that Pd(II)-BINAPHANE afforded the best enantioselectivity. The ee values derived from Pd(II)-BINAPHANE are much higher than those derived from the other three Pd(II) catalysts. A comparison of the catalyst structures shows that the Pd(II)-BINAPHANE catalyst is the only one that has two bulky (R)-binaphthyl groups close to the reaction site. Hence it creates a deep chiral space that can efficiently control the reaction behavior in the carbonyl-ene reactions resulting in excellent enantioselectivity. [source]

    A simple two steps ytterbium triflate-catalysed preparation of 2,2-dimethyl-2h -chromenes from salicylaldehydes and 2-methylpropene

    JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2006
    Soizic Prado
    The preparation of various 2,2-dimethyl-2H -chromenes was achieved in two steps via an ytterbium triflate-catalysed reaction between salicylaldehydes, trimethylorthoformate and 2-methylpropene. From salicylaldehyde, two reaction products were characterised: 4-methoxy-2,2-dimethylchroman and 2-(1,3-dimethoxy-3-methylbutyl)phenol. The former compound probably results from a Lewis acid-catalysed [2+4] cycloaddition between the intermediate quinonemethide and 2-methylpropene whereas the latter may occur via a reaction related to a carbonyl-ene reaction between the quinonemethide and 2-methylpropene. Both compounds were subjected to a catalytic acidic treatment leading to 2,2-dimethyl-2H -chromene. Starting from various salicylaldehydes, the scope of this method was investigated. [source]

    Lewis Acid-Assisted Ene Cyclization of 2-Azetidinone-Tethered Enals: Synthesis of Enantiopure Carbacepham Derivatives

    CHEMISTRY - AN ASIAN JOURNAL, Issue 10 2009
    Benito Alcaide Prof.
    Abstract Diastereocontrolled Lewis acid-catalyzed preparation of enantiopure carbacepham derivatives have been developed starting from 2-azetidinone-tethered enals. The BF3,Et2O-promoted reaction of alkenylaldehydes 1 and 16 is effective as carbocyclization protocol to afford 4-substituted 5-hydroxycarbacephams or 3-substituted 4,5-dihydroxycarbacephams, respectively, by a type I carbonyl-ene reaction, while the BF3,Et2O or SnCl4 -mediated type II carbonyl-ene cyclization of alkenylaldehydes 2 furnishes 3-methylene 5-hydroxycarbacephams along with the corresponding 3-halo 5-hydroxycarbacepham. The stereochemical outcome of these carbonyl-ene cyclizations leading to carbacepham derivatives can be explained in terms of six-membered, cyclic chair-like transition-state models. The formation of halocarbacepham derivatives is proposed to proceed by a stepwise mechanism. Se ha desarrollado una nueva metodología sintética a sistemas ,-lactámicos bicíclicos basada en ciclaciones oxoénicas de los tipos I y II catalizadas por ácidos de Lewis de diferentes alquenil-4-oxoazetidin-2-carbaldehídos. De esta forma, se ha podido acceder, de manera sencilla y diastereoselectiva, a sistemas de carbacefam funcionalizados en forma ópticamente pura. De interés particular resultan los 2-metoxicarbonil-5-hidroxicarbacefams, ya que la presencia de un grupo carbonilo contiguo al nitrógeno ,-lactámico en los sistemas bicíclicos es un requisito fundamental para la actividad biológica de los antibióticos ,-lactámicos. En las ciclaciones oxoénicas de tipo I se ha observado una fuerte influencia de la estereoquímica del aldehido ,-lactámico de partida sobre la estereoselectividad de la reacción, siendo total para los aldehidos cis y baja o moderada para los isómeros trans. En las ciclaciones oxoénicas de tipo II de diferentes aldehidos ,-lactámicos, utilizando tanto SnCl4 como BF3.Et2O como catalizador, junto con los hidroxi-metilencarbacefams esperados, se han obtenido, en casi todos los casos, los correspondientes 3-cloro- o 3-fluorocarbacefams, en proporción variable dependiendo del catalizador utilizado. Este comportamiento, descrito para ácidos de Lewis tales como Me2AlCl o TiCl4, es desconocido para los ácidos de Lewis utilizados por nosotros. [source]

    Palladium(II) Complexes of C2 -Bridged Chiral Diphosphines: Application to Enantioselective Carbonyl-Ene Reactions

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 8 2010
    He-Kuan Luo
    Abstract (11bR,11,bR)-4,4,-(1,2-Phenylene)bis[4,5-dihydro-3H -dinaphtho[2,1- c:1,,2,- e]phosphepin] [abbreviated as (R)-BINAPHANE], (3R,3,R,4S,4,S,11bS,11,bS)-4,4,-bis(1,1-dimethylethyl)-4,4,,5,5,-tetrahydro-3,3,-bi-3H -dinaphtho[2,1- c:1,,2,- e]phosphepin [(S)-BINAPINE], (1S,1,S,2R,2,R)-1,1,-bis(1,1-dimethylethyl)-2,2,-biphospholane [(S,S,R,R)-TANGPHOS] and (2R,2,R,5R,5,R)-1,1,-(1,2-phenylene)bis[2,5-bis(1-methylethyl)phospholane] [(R,R) -i- Pr-DUPHOS] are C2 -bridged chiral diphosphines that form stable complexes with palladium(II) and platinum(II) containing a five-membered chelate ring. The Pd(II)-BINAPHANE catalyst displayed good to excellent enantioselectivities with ee values as high as 99.0% albeit in low yields for the carbonyl-ene reaction between phenylglyoxal and alkenes. Its Pt(II) counterpart afforded improved yields while retaining satisfactory enantioselectivity. For the carbonyl-ene reaction between ethyl trifluoropyruvate and alkenes, the Pd(II)-BINAPHANE catalyst afforded both good yields and extremely high enantioselectivities with ees as high as 99.6%. A comparative study on the Pd(II) catalysts of the four C2 -bridged chiral diphosphines revealed that Pd(II)-BINAPHANE afforded the best enantioselectivity. The ee values derived from Pd(II)-BINAPHANE are much higher than those derived from the other three Pd(II) catalysts. A comparison of the catalyst structures shows that the Pd(II)-BINAPHANE catalyst is the only one that has two bulky (R)-binaphthyl groups close to the reaction site. Hence it creates a deep chiral space that can efficiently control the reaction behavior in the carbonyl-ene reactions resulting in excellent enantioselectivity. [source]