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Enantioselective and Enantiospecific Transition-Metal-Catalyzed Cross-Coupling Reactions of Organometallic Reagents To Construct C-C Bonds.

Cherney AH, Kadunce NT, Reisman SE - Chem. Rev. (2015)

View Article: PubMed Central - PubMed

Affiliation: The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology , Pasadena, California 91125, United States.

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reagents in asymmetric alkyl cross-coupling reactions, with Hayashi, a single example of an asymmetric cross-coupling between sec-alkyl organic halides and organosilicon reagents has been reported stereoconvergent cross-coupling reactions between sec-alkyl electrophiles and either C(sp)- or C(sp)-hybridized organometallic reagents, Sestelo, Sarandeses, (Scheme 9a)... This result and π-allylmetal complex... Unselective reductive selectivity for the (Z)-alkene in most cases; MeMgBr resulted in decreased regioselectivity... increasing the C1–C1′ separation and disfavoring 1,1′ reductive elimination... use in asymmetric allylic alkylation reactions: any successful transformations the allenylmetal and its isomeric propargylmetal species prior to reductive elimination... the analogous asymmetric cross-coupling reactions of tert-alkyl partners represent a largely undeveloped area of great synthetic

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Stereochemical outcomeof allylsilanes in the Hiyama cross-coupling.
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fig35: Stereochemical outcomeof allylsilanes in the Hiyama cross-coupling.

Mentions: Following their studies of Pd-catalyzed enantiospecificcross-couplingreactions of benzyltrifluorosilanes, in 1994, Hiyama and co-workersreported the stereospecific coupling of enantioenriched allyltrifluorosilaneswith aryl triflates (Figure 35).109 Coupling of silane 118 and triflate 119 using Pd(PPh3)4 as the catalyst and CsF as a fluoride source furnished 120 with retention of configuration. However, the solventpolarity and the nature of the fluoride source determined the stereospecificityof the reaction. Replacing CsF with the nonmetallic fluoride sourceTASF delivered ent-120, the productof inversion. In addition, the use of DMF as a polar coordinatingsolvent provides ent-120 with inversionregardless of the fluoride source. As in the coupling of benzylictrifluorosilanes,137 two competing modelsfor transmetalation were proposed by Hiyama. In the presence of CsF,a fluoride bridge between Pd, Cs, and the trifluorosilane promotes syn SE′ transmetalation to Pd, leadingto retention of configuration. Disruption of the fluoride bridge inpolar, coordinating solvents, or by use of nonmetallic fluoride sources,would result in anti SE′ transmetalationto Pd, resulting in inversion of stereochemisty.


Enantioselective and Enantiospecific Transition-Metal-Catalyzed Cross-Coupling Reactions of Organometallic Reagents To Construct C-C Bonds.

Cherney AH, Kadunce NT, Reisman SE - Chem. Rev. (2015)

Stereochemical outcomeof allylsilanes in the Hiyama cross-coupling.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4566132&req=5

fig35: Stereochemical outcomeof allylsilanes in the Hiyama cross-coupling.
Mentions: Following their studies of Pd-catalyzed enantiospecificcross-couplingreactions of benzyltrifluorosilanes, in 1994, Hiyama and co-workersreported the stereospecific coupling of enantioenriched allyltrifluorosilaneswith aryl triflates (Figure 35).109 Coupling of silane 118 and triflate 119 using Pd(PPh3)4 as the catalyst and CsF as a fluoride source furnished 120 with retention of configuration. However, the solventpolarity and the nature of the fluoride source determined the stereospecificityof the reaction. Replacing CsF with the nonmetallic fluoride sourceTASF delivered ent-120, the productof inversion. In addition, the use of DMF as a polar coordinatingsolvent provides ent-120 with inversionregardless of the fluoride source. As in the coupling of benzylictrifluorosilanes,137 two competing modelsfor transmetalation were proposed by Hiyama. In the presence of CsF,a fluoride bridge between Pd, Cs, and the trifluorosilane promotes syn SE′ transmetalation to Pd, leadingto retention of configuration. Disruption of the fluoride bridge inpolar, coordinating solvents, or by use of nonmetallic fluoride sources,would result in anti SE′ transmetalationto Pd, resulting in inversion of stereochemisty.

View Article: PubMed Central - PubMed

Affiliation: The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology , Pasadena, California 91125, United States.

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Please rate it.

reagents in asymmetric alkyl cross-coupling reactions, with Hayashi, a single example of an asymmetric cross-coupling between sec-alkyl organic halides and organosilicon reagents has been reported stereoconvergent cross-coupling reactions between sec-alkyl electrophiles and either C(sp)- or C(sp)-hybridized organometallic reagents, Sestelo, Sarandeses, (Scheme 9a)... This result and π-allylmetal complex... Unselective reductive selectivity for the (Z)-alkene in most cases; MeMgBr resulted in decreased regioselectivity... increasing the C1–C1′ separation and disfavoring 1,1′ reductive elimination... use in asymmetric allylic alkylation reactions: any successful transformations the allenylmetal and its isomeric propargylmetal species prior to reductive elimination... the analogous asymmetric cross-coupling reactions of tert-alkyl partners represent a largely undeveloped area of great synthetic

No MeSH data available.