Asymmetrische Selbstreplikation chiraler 1,2‐Aminoalkohole durch hochenantioselektive, autoinduktive Reduktion

Shibata, Takanori; Takahashi, Tomohide; Konishi, Takashi; Soai, Kenso

doi:10.1002/ange.19971092210

Cited by 8 publications

(3 citation statements)

References 19 publications

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“…In organometallic reactions, if the chiral auxiliary bound to the metal center catalyzes its own production, then it is known as template-directed selfreplication. [208,209] Muaeiz [209b] reported one such asymmetric self-replication in the Sharpless asymmetric aminohydroxylation of sodium methacrylate (Scheme 16; Tos = toluene-4-sulfonyl) in the presence of a non-enantiopure osmium complex 239. Both homochiral and heterochiral 240 undergo hydrolysis in situ to provide 238, with regeneration of catalyst 239.…”

Section: Self-replicationmentioning

confidence: 99%

Nonlinear Effects in Asymmetric Catalysis

Satyanarayana¹,

Abraham²,

Kagan³

2008

Angew Chem Int Ed

500

273

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There is a need for the preparation of enantiomerically pure compounds for various applications. An efficient approach to achieve this goal is asymmetric catalysis. The chiral catalyst is usually prepared from a chiral auxiliary, which itself is derived from a natural product or by resolution of a racemic precursor. The use of non-enantiopure chiral auxiliaries in asymmetric catalysis seems unattractive to preparative chemists, since the anticipated enantiomeric excess (ee) of the reaction product should be proportional to the ee value of the chiral auxiliary (linearity). In fact, some deviation from linearity may arise. Such nonlinear effects can be rich in mechanistic information and can be synthetically useful (asymmetric amplification). This Review documents the advances made during the last decade in the use of nonlinear effects in the area of organometallic and organic catalysis.

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Section: Self-replicationmentioning

confidence: 99%

Nonlinear Effects in Asymmetric Catalysis

Satyanarayana¹,

Abraham²,

Kagan³

2008

Angew Chem Int Ed

500

273

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“…It is important to note that the decrease in enantiomeric excess in the present self-replicating system proceeds more slowly than for conventional template catalysis models [17,27] since hydrolysis of (S,R)-complexes such as 5c and 5d still results in a 50% reproduction of the original catalyst with correct absolute configuration. This represents an over-proportional reproduction of the original stereochemistry and, for identical reproduction fidelity, the herein discussed asymmetric self-replication processes lead to newly generated catalysts with an ee that is even higher than for related autocatalyses.…”

Section: Mathematical Rationalisationmentioning

confidence: 99%

“…[17] He described the enantioselective transformation of a-amino ketones employing a chiral reducing agent, which was generated in situ from lithium aluminium hydride and chiral 1,2-amino alcohols. In Figure 1.…”

Section: Introductionmentioning

confidence: 99%

On the Stereochemical Course of Self‐Replication in Secondary Cycle Sharpless Aminohydroxylation

Muñiz¹

2005

Adv Synth Catal

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An investigation on a potential asymmetric self-replication process within the secondary cycle of Sharpless asymmetric aminohydroxylation is discussed. The reaction of two model olefins is investigated within this process and two different models for an asymmetric process are discussed. Analysis of the results on the basis of these models and a mathematical description for development of the enantiomeric excesses as a function of olefin conversion lead to the conclusion that for such processes there is no possibility for any inhibitory effect and that asymmetric self-replication in secondary cycle aminohydroxylation reactions is not a feasible process.

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Asymmetrische Aktivierung

et al. 2000

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Während nichtracemische Katalysatoren nichtracemische Produkte liefern können, wobei der Enantiomerenüberschuss des Produkts linear oder nichtlinear von dem des Katalysators abhängen kann, führen racemische Katalysatoren immer zu einem racemischen Gemisch chiraler Produkte. Nichtracemische wie racemische asymmetrische Katalysatoren können durch Assoziation mit chiralen Aktivatoren zu hoch aktivierten Katalysatoren weiterentwickelt werden. Diese asymmetrische Aktivierung ist von besonderem Nutzen in der racemischen Katalyse, da nur ein Enantiomer des racemischen Katalysators selektiv aktiviert wird. Ein racemischer Katalysator kann durch ein chirales Additiv entweder selektiv desaktiviert oder, wie wir hier beschreiben, selektiv aktiviert werden. Der Vorteil der Aktivierungsstrategie gegenüber der Desaktivierungsmethode liegt darin, dass der aktivierte Katalysator – sogar bei Verwendung einer katalytischen Menge Aktivator bezogen auf den chiralen Katalysator – einen größeren Enantiomerenüberschuss in den Produkten erzielen kann als der enantiomerenreine Katalysator selbst. Folglich könnte die „asymmetrische Aktivierung“ eine allgemein anwendbare, leistungsfähige Strategie sein, um nicht nur atropisomere, racemische Liganden, sondern auch chiral flexible und „pro‐atropisomere“ Liganden ohne Enantiomerentrennung einsetzen zu können!

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Asymmetrische Selbstreplikation chiraler 1,2‐Aminoalkohole durch hochenantioselektive, autoinduktive Reduktion

Cited by 8 publications

References 19 publications

Nonlinear Effects in Asymmetric Catalysis

Nonlinear Effects in Asymmetric Catalysis

On the Stereochemical Course of Self‐Replication in Secondary Cycle Sharpless Aminohydroxylation

Asymmetrische Aktivierung

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