Design of Brønsted Acid-Assisted Chiral Lewis Acid (BLA) Catalysts for Highly Enantioselective Diels−Alder Reactions

Ishihara, Kazuaki; Kurihara, Hideki; Matsumoto, Masayuki; Yamamoto, Hisashi

doi:10.1021/ja9810282

Cited by 168 publications

(70 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Probably, a Brønsted acid activation of the Lewis acid is occurring. [14] Moreover, the concentration of HOTf in the reaction medium seems crucial. We assume that the slow release of HOTf from the hydolysis of Ga(OTf) 3 is the sine qua non condition for the reaction to proceed in good yields.…”

Section: Resultsmentioning

confidence: 99%

Gallium(III) Triflate Catalyzed Diastereoselective Mukaiyama Aldol Reaction by Using Low Catalyst Loadings

Plancq¹,

Justafort²,

Lafantaisie³

et al. 2013

Eur J Org Chem

View full text Add to dashboard Cite

A mild method for the diastereoselective Mukaiyama aldol reaction is reported. In the presence of a low catalyst loading of gallium(III) triflate (down to 0.01 mol-%), the transformation proceeds efficiently to afford the corresponding β-hydroxyketones in yields of up to 92%. To the best of our knowledge, this is the first report of a metal triflate acting as a safe and bench-stable slow-releasing source of triflic acid for the Mukaiyama aldol reaction. ____________ [a]Prof.

show abstract

Section: Resultsmentioning

confidence: 99%

Gallium(III) Triflate Catalyzed Diastereoselective Mukaiyama Aldol Reaction by Using Low Catalyst Loadings

Plancq¹,

Justafort²,

Lafantaisie³

et al. 2013

Eur J Org Chem

View full text Add to dashboard Cite

show abstract

“…[31] Noch ist der Mechanismus der Iminaktivierung durch die Dicarbonsäure 12 a nicht bekannt, insbesondere ob die Carboxygruppen kooperieren, um eine maximale Aktivierung zu erreichen. [32] Vom Standpunkt des Reaktionsdesigns interessiert besonders die Effizienz des Katalysators, denn die Carbonsäureeinheiten sind bezüglich der Brønsted-Acidität wahrscheinlich den Phosphorsäuren sehr ähnlich, sie verfügen aber nicht über das von den Forschungsgruppen um Akiyama und Terado oft postulierte "basische Sauerstoffatom". [29] Diese Brønsted-Basizität eines Sauerstoffatoms der Phosphorsäuren brachte Terada und Mitarbeiter dazu, eine Deprotonierung der vermuteten Diazoniumion-Zwischenstufe 6 durch den Katalysator anzunehmen.…”

Section: Brønsted-säure-katalysierte Addition An Azomethineunclassified

Protonierung oder Alkylierung? Stereoselektive Brønsted‐Säure‐katalysierte C‐C‐Verknüpfungen mit Diazoalkanen

2010

View full text Add to dashboard Cite

In den letzten Jahren wurden neue Aktivierungsmöglichkeiten für Diazoalkane entdeckt und bereits umfangreich angewendet. Mit chiralen und achiralen Brønsted‐Säuren als Katalysatoren gelangen Kohlenstoff‐Kohlenstoff‐ und Kohlenstoff‐Heteroatom‐Verknüpfungen mit einer zunehmenden Zahl von Diazoalkan‐Derivaten. Auf diesem Weg lassen sich sehr einfach in struktureller und stereochemischer Hinsicht komplizierte Verbindungen erhalten. Außerdem wird auch die konkurrierende Protonierung der Diazoverbindung umgangen – eine Reaktion, die seit langem zur effizienten Veresterung von Carbonsäuren genutzt wird. Achirale Brønsted‐Säuren als Katalysatoren erreichen hohe Diastereoselektivitäten, und chirale Brønsted‐Säuren führen zu den gewünschten Produkten mit sowohl hoher Diastereo‐ als auch Enantioselektivität. Seit einiger Zeit gibt es auch Systeme zur Kohlenstoff‐Kohlenstoff‐Verknüpfung, die eine Brønsted‐Säure mit einer Lewis‐Säure oder einer Übergangsmetallverbindung kombinieren.

show abstract

“…28,29 The structure of a minor isomer was tentatively assigned as regioisomer 10c, based on steric energy calculations (MacroModel), which predicted it to be the third most stable isomer (The steric energy values for the three isomers are given in brackets). Further synthesis was done on the major, desired isomer, 10a.…”

mentioning

confidence: 99%

Bicyclo[2.2.2]octanes: Close structural mimics of the nuclear receptor-binding motif of steroid receptor coactivators

Zhou¹,

Collins²,

Gunther³

et al. 2007

Bioorganic & Medicinal Chemistry Letters

View full text Add to dashboard Cite

Nuclear hormone receptor (NR) function relies on association of agonist-bound receptors with steroid receptor coactivator (SRC) proteins through a small pentapeptide motif (LXXLL) of the SRC that binds to a hydrophobic groove on the NR. We have synthesized a series of bicyclo[2.2.2]octanes that are close structural mimics of the two key lysine residues of this SRC sequence as bound in the hydrophobic groove of the estrogen receptor. These bicyclic systems block the NR-SRC interaction with modest potency.Nuclear receptors (NRs) are transcription factors that control many physiological and pathological processes by directly regulating the expression of select target genes. 1 Members of the NR gene superfamily have multi-domain structures, with a conserved DNAbinding domain and a ligand-binding domain (LBD). The transcriptional activity of NRs is initiated by hormone binding that stabilizes the conformation of the LBD. When an agonist ligand binds, conformational stabilization rigidifies surface features that function as docking sites for coactivator protein complexes that are recruited to modify chromatin structure and activate RNA polymerase II. The most notable of these are the p160 class of steroid receptor coactivators (SRCs). 2,3 X-ray crystallography has revealed details of these NR-SRC interactions, 4-9 which are largely mediated by a short, conserved, pentapeptide LXXLL (L=leucine, X=amino acid) motif of the SRC, termed the NR box. The interaction between the estrogen receptor α (ERα) LBD and a peptide corresponding to NR box 2 of SRC1 (RHKILHRLLQE) is shown in Fig. 1. 5 Selected residues of the peptide interact with the LBD through a two-turn amphipathic α-helical motif that places the first and third leucine residues (L690 and L694) in a deep, solvent-exposed hydrophobic groove made up of residues from various helices of the LBD; histidine and arginine residues of the peptide (H691 and R692, removed for clarity) are solvent exposed and appear unnecessary for the interaction. 5 The intrinsic dipole moment of the coactivator α-helix is aligned with charged residues on the surface of the ERα-LBD (E542 interacts with the peptide N-terminus and K362 with its C-terminus), together forming a "charge clamp". 5The traditional strategy to block agonist signaling of NRs involves hormone antagonists (antihormones) that bind to the LBD, displacing the agonist and stabilizing alternative © 2007 Elsevier Ltd. All rights reserved. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. An alternative approach to interrupting NR signaling is the use of compounds capable of blockin...

show abstract

Design of Brønsted Acid-Assisted Chiral Lewis Acid (BLA) Catalysts for Highly Enantioselective Diels−Alder Reactions

Cited by 168 publications

References 30 publications

Gallium(III) Triflate Catalyzed Diastereoselective Mukaiyama Aldol Reaction by Using Low Catalyst Loadings

Gallium(III) Triflate Catalyzed Diastereoselective Mukaiyama Aldol Reaction by Using Low Catalyst Loadings

Protonierung oder Alkylierung? Stereoselektive Brønsted‐Säure‐katalysierte C‐C‐Verknüpfungen mit Diazoalkanen

Bicyclo[2.2.2]octanes: Close structural mimics of the nuclear receptor-binding motif of steroid receptor coactivators

Contact Info

Product

Resources

About