Asymmetric synthesis of optically active β-substituted ketones by highly enantioselective catalytic conjugate addition of dialkylzinc reagents to enones using a catalyst system of nickel(<scp>II</scp>)-chiral ligand–achiral ligand in acetonitrile/toluene

Soai, Kenso; Hayasaka, Tomoiki; Ugajin, S.

doi:10.1039/c39890000516

Cited by 109 publications

(14 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Soai et al investigated enantioselective alkylations using dialkylzinc reagents 59a. They used N -diphenylphosphinyl imines as electrophiles, and under the influence of an equimolar amount of a chiral amino alcohol such as 41b or 41c , diethylzinc reacted with imine 43 to afford the corresponding amide derivative in a high yield with a high enantioselectivity (Table , entry 5). The catalytic reactions were also investigated.…”

Section: 2 Catalytic Enantioselective Alkylation Of Iminesmentioning

confidence: 99%

Catalytic Enantioselective Addition to Imines

1999

View full text Add to dashboard Cite

Section: 2 Catalytic Enantioselective Alkylation Of Iminesmentioning

confidence: 99%

Catalytic Enantioselective Addition to Imines

1999

View full text Add to dashboard Cite

“…In contrast, in palladium‐catalyzed reductive Heck arylation, mostly different organometallic compounds have been applied as the source of the aryl group. Grignard compounds, organoboron compounds, organozincs, organosilicons and other organometallic reagents have been used in the presence of copper, rhodium, or palladium catalysts. However, due to the high cost of these reagents, their low stability in reaction conditions or in the presence of water, replacing them with aryl halides is a favorable alternative.…”

Section: Introductionmentioning

confidence: 99%

Ligand‐free palladium‐catalyzed tandem pathways for the synthesis of 4,4‐diarylbutanones and 4,4‐diaryl‐3‐butenones under microwave conditions

Wirwis

Trzeciak

2019

Applied Organom Chemis

View full text Add to dashboard Cite

Two efficient Pd‐catalyzed tandem pathways for the synthesis of 4,4‐diaryl‐2‐butanones and 4,4‐diaryl‐3‐buten‐2‐ones were elaborated. The first step in both procedures was the Heck coupling of methyl vinyl ketone (MVK) and various aryl iodides leading to 4‐aryl‐3‐buten‐2‐one with the yield of up to 92% in 1 hr. The second step performed with the same catalyst and a new portion of aryl iodide in the presence K2CO3 as a base produced 4,4‐diaryl‐3‐buten‐2‐ones in high yield. Reaction selectivity changed completely to saturated 4,4‐diaryl‐2‐butanones, reductive Heck products, when a tertiary amine was used instead of K2CO3. Due to the application of microwave irradiation (MW), the desired products were obtained in high yield in a short time (4 hr), using 0.5 mol% of the Pd (OAc)2 catalyst without additional ligands.

show abstract

“…Since chiral ligands based on ephedrine or norephedrine have been and still are widely used in asymmetric catalysis, it appeared important to study other derivatives of this family in the context of non-linear effect. Among all the derivatives, N-pyrrolidinyl norephedrine (NPNE) attracted our attention [11,12] because it has not been probed yet for NLEs in a systematic way, although it is one of the most enantioselective ligands in ephedrine-based catalytic organozinc additions.…”

Section: Introductionmentioning

confidence: 99%

Observation of Hyperpositive Non-Linear Effect in Asymmetric Organozinc Alkylation in Presence of N-Pyrrolidinyl Norephedrine

2022

View full text Add to dashboard Cite

Phenomena related to asymmetric amplification are considered to be key to understanding the emergence of homochirality in life. In asymmetric catalysis, theoretical and experimental models have been studied to understand such chiral amplification, in particular based on non-linear effects. Three decades after the theoretical demonstration that a chiral catalyst, when not enantiopure, could be more enantioselective than its enantiopure counterpart, we show here a new experimental example of nonlinear hyperpositive effect. We report here our investigations in the enantioselective zinc-catalyzed alkylation of benzaldehyde with N-pyrrolidinyl norephedrine as partially resolved chiral ligand, which shows a significant hyperpositive non-linear effect. A study of the underlying mechanism was conducted, which allows us to confirm a mechanism that implies a monomeric and a dimeric complex both catalyzing the reaction at a steady state and giving different enantioselectivities.

show abstract

Asymmetric synthesis of optically active β-substituted ketones by highly enantioselective catalytic conjugate addition of dialkylzinc reagents to enones using a catalyst system of nickel(II)-chiral ligand–achiral ligand in acetonitrile/toluene

Abstract: Highly enantioselective conjugate addition of dialkylzinc reagents to aryl substituted enones using Ni(ii)-bipyridyl-chiral ligand in acetonitrile (MeCN)/toluene as an in situ prepared catalyst system affords P-substituted ketones in up to 90% enantiomeric excess (e.e.).

Cited by 109 publications

References 0 publications

Catalytic Enantioselective Addition to Imines

Catalytic Enantioselective Addition to Imines

Ligand‐free palladium‐catalyzed tandem pathways for the synthesis of 4,4‐diarylbutanones and 4,4‐diaryl‐3‐butenones under microwave conditions

Observation of Hyperpositive Non-Linear Effect in Asymmetric Organozinc Alkylation in Presence of N-Pyrrolidinyl Norephedrine

Contact Info

Product

Resources

About