Enantioselektive 1,2‐Additionen von Li‐, Mg‐, Zn‐ und Cu‐organischen Verbindungen und von Li‐Enolaten an Carbonylverbindungen im chiralen Medium DDB

Abstract

Enantioselective 1,2-addition of Li-, Mg-, Zn-, and Cu-organic compounds and of Li-enolates to carbonyl derivatives in the chiral medium DDB') SummaryThe (+ )-enantiomer of the methoxyamine DDB is used as a chiral cosolvent in the title reactions. As evident from the results listed in the

Chiral Ligands in the Asymmetric Reformatsky Reaction

“…(6)). Similar results were observed by Soai [30,31]. They observed an increase in the size of the alkyl group on the nitrogen led to a decrease in the rate of reaction with a similar enantioselectivity.…”

“…The enantioselectivities were moderate (21 to 70% e.e.) As observed by Soai et al, these reactions showed that the presence of free hydroxyl group is a significant factor [30,31]. Similar results were observed by Soai [30,31].…”

“…In these studies, aldehyde (benzaldehyde) and ketones (acetophenone and phenylethylketone) were used as carbonyl compounds (CC), (-)-sparteine (1) (Fig. [30]. The molar ratio applied in these reactions were 1:1.1:1.1 (CC:L*:RR), which led from poor to moderate chemical yields (13 -62%).…”

Prediction of enhanced solvent-induced enantioselectivity for a ring opening with a bifurcating reaction path

“…[5][6][7][8] So far, larger effects have been found only when the solvent becomes covalently bound to a reactant or reagent. [9][10][11] This is presumably because noncovalent solvent-solute interactions are usually rather weak, and differences between the interactions of the two enantiomers of a chiral solute with a given enantiomer of the solvent are consequently even smaller.…”

1-Alkenyllithium-Reagentien mit einem Heteroatomsubstituenten in derα-Position: Carbanionen und Carbenoide zur C-C-Verknüpfung

“…[137] Aber auch a-heterosubstituierte Carbanionen mit kovalent gebundenen chiralen Hilfsgruppen wurden selten eingesetzt; [138,139] manchmal ist die chirale Information schwer einzuführen und wird bei der Freisetzung der Zielmoleküle zerstört, in anderen Fällen ist die Stereoselektivität gering. [140] Wesentlich erfolgreicher sind Ansätze, die nicht auf der direkten Addition chiraler Synthone an Aldehyde beruhen, sondern ¹auf Umwegenª zu nichtracemischen a-Hydroxy- [141] und a-Aminocarbonylverbindungen [142] gelangen.…”