Asymmetric α-Allylation Research Articles

Asymmetric α-Allylation by Copper/Palladium Dual Catalysis

Asymmetric α-Allylation by Copper/Palladium Dual Catalysis

Cu/Pd Synergistic Dual Catalysis: Asymmetric α-Allylation of an α-CF3 Amide.

Despite the burgeoning demand for fluorine-containing chemical entities, the construction of CF3 -containing stereogenic centers has remained elusive. Herein, we report the strategic merger of CuI /base-catalyzed enolization of an α-CF3 amide and Pd0 -catalyzed allylic alkylation in an enantioselective manner to deliver chiral building blocks bearing a stereogenic carbon center connected to a CF3 , an amide carbonyl, and a manipulable allylic group. The phosphine complexes of CuI and Pd0 engage in distinct catalytic roles without ligand scrambling to render the dual catalysis operative to achieve asymmetric α-allylation of the amide. The stereoselective cyclization of the obtained α-CF3 -γ,δ-unsaturated amides to give tetrahydropyran and γ-lactone-fused cyclopropane skeletons highlights the synthetic utility of the present catalytic method as a new entry to non-racemic CF3 -containing compounds.

Cu/Pd Synergistic Dual Catalysis: Asymmetric α‐Allylation of an α‐CF3 Amide

AbstractDespite the burgeoning demand for fluorine‐containing chemical entities, the construction of CF3‐containing stereogenic centers has remained elusive. Herein, we report the strategic merger of CuI/base‐catalyzed enolization of an α‐CF3 amide and Pd0‐catalyzed allylic alkylation in an enantioselective manner to deliver chiral building blocks bearing a stereogenic carbon center connected to a CF3, an amide carbonyl, and a manipulable allylic group. The phosphine complexes of CuI and Pd0 engage in distinct catalytic roles without ligand scrambling to render the dual catalysis operative to achieve asymmetric α‐allylation of the amide. The stereoselective cyclization of the obtained α‐CF3‐γ,δ‐unsaturated amides to give tetrahydropyran and γ‐lactone‐fused cyclopropane skeletons highlights the synthetic utility of the present catalytic method as a new entry to non‐racemic CF3‐containing compounds.

On the regioselectivity and diastereoselectivity of ACC hydrazone alkylation

The asymmetric α-allylation of 3-pentanone using several different N-amino cyclic carbamate (ACC) auxiliaries is described. The level of asymmetric induction was found to range from er = 93:7 to er = 99:1. The factors that lead to compromised selectivity for the various auxiliaries have been determined. Significantly, we have established that using the easily accessible and inexpensive valine-derived ACC auxiliary, it is possible to obtain synthetically useful levels of asymmetric induction (er = 96:4).

ChemInform Abstract: Phosphoric Acid Based Heterodimers in Asymmetric Catalysis

AbstractReview: [59 refs.

Uniting C1-Ammonium Enolates and Transition Metal Electrophiles via Cooperative Catalysis: The Direct Asymmetric α-Allylation of Aryl Acetic Acid Esters.

The direct, catalytic, asymmetric α-functionalization of acyclic esters constitutes a significant challenge in the area of asymmetric catalysis, particularly where the configurational integrity of the products is problematic. Through the unprecedented merger of two independent, yet complementary, catalysis events it has been possible to facilitate the direct asymmetric α-allylation of readily available aryl acetic acid esters. Since enantioselection is determined by the nucleophile, this conceptual approach to cooperative catalysis constitutes a potentially general solution to the direct catalytic asymmetric α-functionalization of acyclic esters.

Asymmetric Catalysis with CO2: The Direct α‐Allylation of Ketones

Quaternary stereocenters are found in numerous bioactive molecules. The Tsuji-Trost reaction has proven to be a powerful C-C bond forming process, and, at least in principle, should be well suited to access quaternary stereocenters via the α-allylation of ketones. However, while indirect approaches are known, the direct, catalytic asymmetric α-allylation of branched ketones has been elusive until today. By combining "enol catalysis" with the use of CO2 as a formal catalyst for asymmetric catalysis, we have now developed a solution to this problem: we report a direct, highly enantioselective and highly atom-economic Tsuji-Trost allylation of branched ketones with allylic alcohol. Our reaction delivers products bearing quaternary stereocenters with high enantioselectivity and water as the sole by-product. We expect our methodology to be of utility in asymmetric catalysis and inspire the design of other highly atom-economic transformations.

Phosphoric Acid Based Heterodimers in Asymmetric Catalysis

Chiral phosphoric acid diesters arguably constitute the most exploited class of catalysts in asymmetric Bronsted acid catalysis. Despite being highly investigated for their acidic properties, these compounds display an amphoteric nature, which has instead been considerably overlooked. The potential of this dichotomous polarity has recently been disclosed and applied to the development of novel reaction modes in organocatalysis. In this account, we present our recent advances in this area, focusing on the establishment of heterodimeric interactions toward the nucleophilic activation of carboxylic acids, thiocarboxylic acids and ketones (via their enols) in asymmetric transformations. 1 Introduction 2 Discovery of Heterodimeric Self-Assemblies 3 Activation of Carboxylic Acids 3.1 The Enantioselective Carboxylysis of Aziridines 3.2 An Asymmetric Hydrolysis of Epoxides 4 Activation of Thiocarboxylic Acids 5 Enol Catalysis 5.1 Asymmetric Michael Addition 5.2 Asymmetric α-Amination 5.3 Asymmetric α-Allylation 6 Concluding Remarks

Asymmetric α-Allylation of α-Branched Aldehydes with Allyl Alcohols by Synergistic Catalysis Using an Achiral Palladium Complex and a Chiral Primary Amino Acid

Highly enantioselective direct α-allylation of α-branched aldehydes with simple allyl alcohols was achieved by the combined use of an achiral transition-metal catalysis with a palladium complex and a chiral organocatalysis with a readily obtainable primary α-amino acid. Various α-allylated aldehydes possessing a stereocontrolled quaternary carbon stereogenic center were synthesized in high yields with high enantioselectivity.

Direct Asymmetric α-Allylation of α-Branched Aldehydes by Two Catalytic Systems with an Achiral Pd Complex and a Chiral Primary α-Amino Acid

Direct α-allylation of α-branched aldehydes was successfully carried out with a readily available allyl ester by combined use of two catalytic systems: Tsuji-Trost allylation reaction with an achiral palladium complex and enamine catalysis with a chiral primary α-amino acid. A quaternary carbon stereogenic center was constructed stereoselectively to give various 2,2-disubstituted pent-4-enals in good yields with high enantioselectivity.

Electrophilic Rearrangements of Chiral Amides: A Traceless Asymmetric α-Allylation

A one-pot protocol for the asymmetric α-allylation reaction is reported relying on a key efficient asymmetric Claisen rearrangement, triggered by electrophilic activation of chiral pseudoephedrine amides. Subsequent reduction or hydrolysis of the resulting iminium ions provides highly enantioenriched α-allylic aldehydes or carboxylic acids in a traceless manner. Compared to traditional alternatives which make use of strongly basic conditions, the work presented herein displays unprecedented functional group tolerance.

Corrigendum: Direct Asymmetric α-Allylation of Aldehydes with Simple Allylic Alcohols Enabled by the Concerted Action of Three Different Catalysts

Corrigendum: Direct Asymmetric α-Allylation of Aldehydes with Simple Allylic Alcohols Enabled by the Concerted Action of Three Different Catalysts

Direct Asymmetric α-Allylation of Ketones with Allylic Alcohols via Pd/Enamine Cooperative Function

Direct Asymmetric α-Allylation of Ketones with Allylic Alcohols via Pd/Enamine Cooperative Function

Asymmetric α-Allylation of Aldehydes with Simple Allylic Alcohols

Asymmetric α-Allylation of Aldehydes with Simple Allylic Alcohols

Intramolecular Asymmetric α-Allylation of Aldehydes via SOMO Umpolung

The authors expand SOMO catalysis to the intramolecular α-allylation of aldehydes using a secondary amine catalyst. Under the oxidative reaction conditions [using >2 equiv of ceric ammonium nitrate (CAN)], aldehyde-tethered allylsilanes could be converted into the desired cyclic compounds with good yield and enantioselecti­vity. Addition of water (2 equiv) could increase chemical yield and diastereoselectivity, however, not the enantioselectivity (see more mechanistic details: Angew. Chem. Int. Ed. 2010, 49, 6106). The presented methodology can be utilized to construct five- and six-membered cyclic compounds with aldehyde and olefin functionalities.

Asymmetric Induction Reactions. VII. Palladium-Catalyzed Asymmetric .ALPHA.-Allylations of Carbonyl Compounds Using Chiral Sulfonamides as Chiral Ligands.

Palladium-catalyzed asymmetric α-allylations of carbonyl compounds were studied using various kinds of chiral sulfonamides derived from optically active α-amino acids as chiral ligands. Participation of the sulfonamide functionality in the palladium catalysis is discussed.

キラルπ‐アリル遷移金属錯体を経由する不斉反応の立体化学

Our recent works concerning asymmetric synthesis via chiral π-allyl transition metal complexes are reviewed; focussed on inter- and intramolecular asymmetric palladium-catalyzed allylations of chiral enamines, imines, and hydrazones bearing allyl esters or phosphine groups, and intramolecular asymmetric metallo-ene reactions. A novel and excellent method for asymmetric α-allylation of carbonyl compounds via their chiral enamines and imines bearing allyl esters has been developed. Readily available chiral allyl esters, (S) -proline and (S) -valine allyl ester, have been found to serve as good asymmetric allylating reagents in the palladium-catalyzed reactions of the chiral enamines and imines derived from them.

ChemInform Abstract: Asymmetric Induction Reactions. Part 5. Palladium‐Catalyzed Asymmetric α‐Allylations of Carbonyl Compounds with Chiral Allyl Esters via Enamines and Imines.

AbstractChemInform 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.

Asymmetric induction reactions. V. The palladium-catalyzed asymmetric .alpha.-allylation of carbonyl compounds with chiral allyl esters via enamines and imines

A novel and excellent method for asymmetric α-allylation of carbonyl compounds via their chiral enamines or imines bearing allyl esters has been developed. Readily available chiral allyl esters having chirality at the a-position of the ester carbonyl group, such as (S)-proline and other (S)-α-amino acid allyl esters, have been found to serve as good asymmetric allylating reagents in palladium-catalyzed reactions of the chiral enamines and imines derived from them. The use of (S)-proline or (S)-valine allyl esters as the amino parts in the enamines or imines provided the highest optical yields of the corresponding α-allyl carbonyl compounds. A mechanism for asymmetric induction is proposed based on the stereochemical results obtained

ChemInform Abstract: Palladium‐Catalyzed Asymmetric α‐Allylations of Carbonyl Compounds via Chiral Imines (III), (VI) Derived from Optically Active α‐Amino Acid Allyl Esters.

ChemInformVolume 21, Issue 40 Preparative Organic Chemistry ChemInform Abstract: Palladium-Catalyzed Asymmetric α-Allylations of Carbonyl Compounds via Chiral Imines (III), (VI) Derived from Optically Active α-Amino Acid Allyl Esters. K. HIROI, K. HIROI Dep. Synth. Org. Chem., Tohoku Coll. Pharm., Sendai, Miyagi 981, JapanSearch for more papers by this authorT. KOYAMA, T. KOYAMA Dep. Synth. Org. Chem., Tohoku Coll. Pharm., Sendai, Miyagi 981, JapanSearch for more papers by this authorK. ANZAI, K. ANZAI Dep. Synth. Org. Chem., Tohoku Coll. Pharm., Sendai, Miyagi 981, JapanSearch for more papers by this author K. HIROI, K. HIROI Dep. Synth. Org. Chem., Tohoku Coll. Pharm., Sendai, Miyagi 981, JapanSearch for more papers by this authorT. KOYAMA, T. KOYAMA Dep. Synth. Org. Chem., Tohoku Coll. Pharm., Sendai, Miyagi 981, JapanSearch for more papers by this authorK. ANZAI, K. ANZAI Dep. Synth. Org. Chem., Tohoku Coll. Pharm., Sendai, Miyagi 981, JapanSearch for more papers by this author First published: October 2, 1990 https://doi.org/10.1002/chin.199040114AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume21, Issue40October 2, 1990 RelatedInformation