A Catalytic and Enantioselective Desymmetrization of <i>meso</i> Cyclic Allylic Bisdiethylphosphates with Organozinc Reagents

Piarulli, Umberto; Daubos, Philippe; Claverie, Christelle K.; Roux, Maryline; Gennari, Cesare

doi:10.1002/anie.200390088

Cited by 83 publications

(15 citation statements)

References 29 publications

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“…In the past decades, asymmetric allylic alkylation (AAA) reactions have emerged as powerful tools − that may accommodate both achiral and chiral substrates. Enantioselective Cu-catalyzed AAA to prochiral materials can now be readily achieved by an array of nucleophiles, ligands, and leaving groups. ,,,− While numerous mechanistic overviews have been outlined, detailed analyses of asymmetric Cu-catalyzed pathways are scarce and rely on analogy with work on stoichiometric nonenantioselective methods. To date, the most insight into these mechanisms has been brought by the Bäckvall, − Nakamura, ,− Alexakis, and Feringa groups, all of which clearly emphasize the complexity of these mechanisms and the challenges associated with their study.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Studies on a Cu-Catalyzed Asymmetric Allylic Alkylation with Cyclic Racemic Starting Materials

et al. 2017

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Mechanistic studies on Cu-catalyzed asymmetric additions of alkylzirconocene nucleophiles to racemic allylic halide electrophiles were conducted using a combination of isotopic labeling, NMR spectroscopy, kinetic modeling, structure-activity relationships, and new reaction development. Kinetic and dynamic NMR spectroscopic studies provided insight into the oligomeric Cu-ligand complexes, which evolve during the course of the reaction to become faster and more highly enantioselective. The Cu-counterions play a role in both selecting different pathways and in racemizing the starting material via formation of an allyl iodide intermediate. We quantify the rate of Cu-catalyzed allyl iodide isomerization and identify a series of conditions under which the formation and racemization of the allyl iodide occurs. We developed reaction conditions where racemic allylic phosphates are suitable substrates using new phosphoramidite ligand D. D also allows highly enantioselective addition to racemic seven-membered-ring allyl chlorides for the first time. H andH NMR spectroscopy experiments on reactions using allylic phosphates showed the importance of allyl chloride intermediates, which form either by the action of TMSCl or from an adventitious chloride source. Overall these studies support a mechanism where complex oligomeric catalysts both racemize the starting material and select one enantiomer for a highly enantioselective reaction. It is anticipated that this work will enable extension of copper-catalyzed asymmetric reactions and provide understanding on how to develop dynamic kinetic asymmetric transformations more broadly.

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Section: Introductionmentioning

confidence: 99%

Mechanistic Studies on a Cu-Catalyzed Asymmetric Allylic Alkylation with Cyclic Racemic Starting Materials

et al. 2017

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“…We have recently disclosed a new highly regio‐, diastereo‐,and enantioselective desymmetrisation of meso , cyclic allylic bis(diethyl phosphates) with organozinc reagents catalysed by copper( I ) complexes of chiral Schiff‐base ligands 1 7and of chiral, binaphthol derived, phosphoramidites 2 (Scheme ) 8…”

Section: Introductionmentioning

confidence: 99%

Copper‐Catalysed, Enantioselective Desymmetrisation of meso Cyclic Allylic Bis(diethyl phosphates) with Organozinc Reagents

et al. 2005

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A highly regio-, diastereo-and enantioselective desymmetrization of five-, six-, and seven-membered meso, cyclic allylic bis(diethyl phosphates) (3-5) with organozinc reagents was developed, using catalytic amounts (10 mol%) of [Cu(OTf)] 2 ·C 6 H 6 and two different classes of chiral ligands: Schiff bases 1 and phosphoramidites 2. Good to excellent enantioselectivities were obtained for every substrate by a subtle balance of ligand structure and experimental conditions. In particular, ee's of up to 88 % were obtained for the fivemembered ring substrate 3 with ligands 1cjo and 1cjm using Et 2 Zn (94 % ee with Me 2 Zn, 88 % ee with nBu 2 Zn). Schiffbase ligands 1 were not effective with the six-and seven-

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“…[48] The chiral copper(I) complex with the Schiff base promoted the asymmetric addition of diethylzinc to cyclic allylic bisdiethylphosphates with a high control over the regio-, diastereo-and enantioselectivity. As illustrated in Scheme 36, the reaction upon the cyclopentene substrate 90 produced a specific S N 2' adduct with an anti stereochemical mechanism.…”

Section: Organozinc Reagentsmentioning

confidence: 99%

Copper‐Catalyzed Asymmetric Allylic Alkylation

2008

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A Catalytic and Enantioselective Desymmetrization of meso Cyclic Allylic Bisdiethylphosphates with Organozinc Reagents

Cited by 83 publications

References 29 publications

Mechanistic Studies on a Cu-Catalyzed Asymmetric Allylic Alkylation with Cyclic Racemic Starting Materials

Mechanistic Studies on a Cu-Catalyzed Asymmetric Allylic Alkylation with Cyclic Racemic Starting Materials

Copper‐Catalysed, Enantioselective Desymmetrisation of meso Cyclic Allylic Bis(diethyl phosphates) with Organozinc Reagents

Copper‐Catalyzed Asymmetric Allylic Alkylation

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