Hochenantioselektive katalytische 1,4‐Addition und kombinierte 1,4‐Addition/Aldolreaktion von Organozinkreagentien an Enone

Feringa, Ben L.; Pineschi, Mauro; Arnold, Leggy A.; Imbos, Rosalinde; Vries, André H.M. de

doi:10.1002/ange.19971092316

Cited by 100 publications

(48 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…On the basis of this information on the face-selectivity step, we consider that the role of effective chiral ligands reported recently [55] is to selectively accelerate reductive elimination of the CPop intermediate, most likely through complexation of the phosphorus moiety of the ligand to the Cu III atom in TScc. Note that this view is quite different from the prevailing views on enantiofacially selective conjugate addition that focus on the copper/olefin 1-complexation stage (e.g.…”

Section: Resultsmentioning

confidence: 99%

Density Functional Studies on Conjugate Addition of (Me2CuLi)2 to Cyclohexenone: Stereoselectivity and Rate-Determining Step

Mori

Nakamura

1999

Chem. Eur. J.

View full text Add to dashboard Cite

The reaction pathway of the conjugate addition of a dimeric cuprate (Me 2 CuLi) 2 to 2-cyclohexenone has been studied by means of the B3LYP hybrid density functional method, and intermediates and transition structures (TSs) on the potential surface of the reaction have been determined. A lithium/carbonyl coordination complex (CPli), a copper/olefin complex retaining a closed cuprate structure (CPcl), a copper/olefin complex with an open cuprate structure (CPop), and the TS of CÀC bond formation (TScc) have been located along the gas-phase pathway leading to the conjugate addition product (PD). We studied two diastereoisomeric pathways, and found that the pathway that results in the axial placement of the nucleophilic methyl group in the product was favored throughout the course of the reaction, except in the product complex. Thus, the stereoselectivity of the conjugate addition to cyclohexenone originates from the stereochemical preference of the final, ratelimiting C À C bond formation stage that mainly reflects the steric factors in the formation of 3-methylcyclohexanone enolate in its half-chair form (TSccax).Comparison of the calculated and experimental values for 13 C NMR chemical shift and kinetic isotope effects strongly suggests that the copper/olefin complex of the CPop structural type is the reactive intermediate that directly forms the product. Thus, the open complex CPop, rather than the closed complex CPcl hitherto considered, is a direct precursor of the product and crucial for the stereoselectivity of the conjugate addition. On the basis of theory and experiments, transition-state models for the conjugate addition to substituted cyclohexenones are provided.

show abstract

Section: Resultsmentioning

confidence: 99%

Density Functional Studies on Conjugate Addition of (Me2CuLi)2 to Cyclohexenone: Stereoselectivity and Rate-Determining Step

Mori

Nakamura

1999

Chem. Eur. J.

View full text Add to dashboard Cite

show abstract

“…Our approach is to apply the rhodium-catalyzed asymmetric 1,4-addition [8,9] to the asymmetric synthesis of a-aryl ketones. Herein we report that the asymmetric 1,4-addition of aryl-and alkenylboron reagents to quinone monoketals [10] is efficiently catalyzed by a chiral diene/rhodium complex [11][12][13][14] and one of the enantioenriched addition products (96-99 % ee) is readily converted into a 2-aryltetralone without loss of enantiomeric purity. …”

mentioning

confidence: 99%

Asymmetric 1,4‐Addition of Organoboron Reagents to Quinone Monoketals Catalyzed by a Chiral Diene/Rhodium Complex: A New Synthetic Route to Enantioenriched 2‐Aryltetralones

Tokunaga

Hayashi

2007

Adv Synth Catal

View full text Add to dashboard Cite

A novel synthetic approach to 2-aryltetralones with high ee has been developed through asymmetric 1,4-addition of arylboronic acids to naphthoquinone monoketals catalyzed by a rhodium complex with the (R,R)-Ph-bod* ligand. The asymmetric addition proceeded in high yields with excellent enantioselectivity.Keywords: asymmetric catalysis; boron; chiral diene ligands; conjugate addition; quinone monoketals; rhodium Enantiomerically pure carbonyl compounds bearing aryl or alkenyl groups at the a position to the carbonyl moiety, which are represented by the 2-aryltetralones, constitute key intermediates to biologically important compounds.[1] Although their preparation using a stoichiometric amount of chiral reagents has been reported, [1,2] their catalytic asymmetric synthesis has not been well developed. The palladium-or nickel-catalyzed asymmetric a-arylation [3] and a-alkenylation [4] of carbonyl compounds provides an efficient method for the synthesis of chiral ketones substituted with quaternary stereogenic centers, but their application to the asymmetric synthesis of products containing hydrogen at the chiral carbon should present a problem due to the difficulty in keeping the stereogenic character of the chiral carbon center bound to an acidic hydrogen under basic conditions at a high reaction temperature. Another important method of providing a-chiral ketones is the catalytic asymmetric protonation of enolates, [5][6][7] but the asymmetric synthesis at the stage of carbon-carbon bond formation is more desirable. Our approach is to apply the rhodium-catalyzed asymmetric 1,4-addition [8,9] to the asymmetric synthesis of a-aryl ketones. Herein we report that the asymmetric 1,4-addition of aryl-and alkenylboron reagents to quinone monoketals [10] is efficiently catalyzed by a chiral diene/rhodium complex [11][12][13][14] and one of the enantioenriched addition products (96-99 % ee) is readily converted into a 2-aryltetralone without loss of enantiomeric purity.

show abstract

“…For example, the hydrogenation of 1a was completed within 6 h in the presence of 10 mol% KI, yielding the product (R)-2a in the same ee value as that with added I 2 (entry 12 vs. 1). Ligand comparison showed that the binaphthol-based phosphoramidites (S a ,S,S)-Monophos-pe [(S a ,S,S)-4a] and (S a ,R,R)-Monophos-pe [(S a ,R,R)-4b] [25] were also suitable ligands for the reaction (80% ee and 94% ee, respectively) and the configuration of product was interestingly mainly determined by the chirality of the amino moiety of the ligand Monophos-pe (entries 21 and 22). In contrast, other monodentate phosphorus ligands (entries [15][16][17][18][19][20] and bidentate phosphine ligands such as SDP, BINAP and Josiphos (data not shown) were unsuitable for this reaction, giving very low ee values.…”

Section: Resultsmentioning

confidence: 99%

Enantioselective Synthesis of Chiral Tetrahydroisoquinolines by Iridium‐Catalyzed Asymmetric Hydrogenation of Enamines

et al. 2009

View full text Add to dashboard Cite

Chiral iridium complexes based on spiro phosphoramidite ligands are demonstrated to be highly efficient catalysts for the asymmetric hydrogenation of unfunctionalized enamines with an exocyclic double bond. In combination with excess iodine or potassium iodide and under hydrogen pressure, the complex Ir/A C H T U N G T R E N N U N G (S a ,R,R)-3a provides chiral N-alkyl-A C H T U N G T R E N N U N G tetrahydroisoquinolines in high yields with up to 98% ee. The L/Ir ratio of 2:1 is crucial for obtaining a high reaction rate and enantioselectivity. A deuterium labeling experiment showed that an inverse isotope effect exists in this reaction. A possible catalytic cycle including an iridiumA C H T U N G T R E N N U N G (III) species bearing two monophosphoramidite ligands is also proposed.

show abstract

Hochenantioselektive katalytische 1,4‐Addition und kombinierte 1,4‐Addition/Aldolreaktion von Organozinkreagentien an Enone

Cited by 100 publications

References 28 publications

Density Functional Studies on Conjugate Addition of (Me2CuLi)2 to Cyclohexenone: Stereoselectivity and Rate-Determining Step

Density Functional Studies on Conjugate Addition of (Me2CuLi)2 to Cyclohexenone: Stereoselectivity and Rate-Determining Step

Asymmetric 1,4‐Addition of Organoboron Reagents to Quinone Monoketals Catalyzed by a Chiral Diene/Rhodium Complex: A New Synthetic Route to Enantioenriched 2‐Aryltetralones

Enantioselective Synthesis of Chiral Tetrahydroisoquinolines by Iridium‐Catalyzed Asymmetric Hydrogenation of Enamines

Contact Info

Product

Resources

About