Publications associées à Racemization

Chalcogen bonding catalysis

Catalysts play a major role in chemical synthesis, and catalysis is considered to be a green and economic process. Catalysis is dominated by covalent interactions between the catalyst and substrate. The design of non-covalent catalysts came into limelight ...

Royal Society of Chemistry2024

In depth analysis of heterogeneous catalysts for the chemoenzymatic dynamic kinetic resolution of beta-amino esters

Kumar Varoon Agrawal, Cédric Karel J Van Goethem

The chemoenzymatic dynamic kinetic resolution of beta-amino esters is established after detailed evaluation of metal-based heterogeneous catalysts for racemization and enzyme catalysts for kinetic resolution. Several heterogeneous palladium catalysts prove ...

ROYAL SOC CHEMISTRY2022

Schiff base ligands derived from 1,2-bis(2 '-nitro-/amino-phenoxy)-3-R-benzene and 2-hydroxy-1-naphthaldehyde and their Cu/Zn(II) complexes: synthesis, characterization, X-ray structures and computational studies

Rosario Scopelliti

1,2-Bis(2'-nitrophenoxy)-3-R-benzenes {R = H (1), CH3 (2) and OCH3 (3)} have been prepared from the S-N-Ar reaction between 1-fluoro-2-nitrobenzene and 3-R-catechol (aromatic diol), and are then reduced to the corresponding diamines 1,2-bis(2'-aminophenoxy ...

ROYAL SOC CHEMISTRY2021

Visible-Light-Driven Catalytic Deracemization of Secondary Alcohols

Xile Hu, Zhikun Zhang

Deracemization of racemic chiral compounds is an attractive approach in asymmetric synthesis, but its development has been hindered by energetic and kinetic challenges. Here we describe a catalytic deracemization method for secondary benzylic alcohols whic ...

Wiley-VCH Verlag GmbH2021

In vivo detection of d-amino acid oxidase with hyperpolarized d-[1-C-13]alanine

Rolf Gruetter, Hikari Ananda Infinity Yoshihara, Alice Radaelli

d-amino acid oxidase (DAO) is a peroxisomal enzyme that catalyzes the oxidative deamination of several neutral and basic d-amino acids to their corresponding alpha-keto acids. In most mammalian species studied, high DAO activity is found in the kidney, liv ...

2020

Chiral expression of adsorbed (MP) 5-amino[6] helicenes: from random structures to dense racemic crystals by surface alloying

Magalí Alejandra Lingenfelder

The chiral expression of a molecule on a surface is driven from a random solid solution on Cu(100) to a racemic crystal on a Sn/Cu(100) alloy. Density functional theory simulations reveal how the growth of the racemate is influenced by the underlying surfa ...

Royal Society of Chemistry2017

Racemization of undesired enantiomers: Immobilization of mandelate racemase and application in a fixed bed reactor

Production of optically pure products can be based on simple unselective synthesis of racemic mixtures combined with a subsequent separation of the enantiomers; however, this approach suffers from a 50% yield limitation which can be overcome by racemizatio ...

Wiley-V C H Verlag Gmbh2016

Stereocontrolled Self-Assembly and Self-Sorting of Luminescent Europium Tetrahedral Cages

Jean-Claude Bünzli

Coordination-directed self-assembly has become a well-established technique for the construction of functional supramolecular structures. In contrast to the most often exploited transition metals, trivalent lanthanides Ln(III) have been less utilized in th ...

American Chemical Society2015

Tuning the Reactivity of Isocyano Group: Synthesis of Imidazoles and Imidazoliums from Propargylamines and Isonitriles in the Presence of Multiple Catalysts

Qian Wang, Jieping Zhu, Shuo Tong

The reaction of propargyl amines with tert-butylisonitrile in the presence of a catalytic amount of both Yb(OTf)3 and AgOTf afforded imidazoles, whereas the same reaction with primary and secondary alkylisonitriles, as well as arylisonitriles, in the prese ...

Wiley-Blackwell2015

Enantioselective Synthesis of Polycyclic Carbocycles via an Alkynylation-Allylation-Cyclization Strategy

Jérôme Waser, Pascal Miéville, Maria Victoria Vita

A new general three-stage strategy to access polycyclic ring systems bearing all-carbon quaternary centers with high enantioselectivity is reported. The required starting materials were readily accessed in racemic form through the alpha-alkynylation of ket ...

American Chemical Society2014

Lack of Enantioselectivity in the SULT1A3-catalyzed Sulfoconjugation of Normetanephrine Enantiomers: An In Vitro and Computational Study

Sandrine Gerber, Jean-Baptiste Gualtierotti

(1R)-Normetanephrine is the natural stereoisomeric substrate for sulfotransferase 1A3 (SULT1A3)-catalyzed sulfonation. Nothing appears known on the enantioselectivity of the reaction despite its potential significance in the metabolism of adrenergic amines ...

Wiley-Blackwell2013

Cinchona Alkaloid-Amides Catalyzed Enantioselective Formal [2+2] Cycloadditions of Allenoates and Imines: Enantioselective Synthesis of 2,4-Substituted Azetidines

Jieping Zhu

Mix and go. The quinidine-amide (1)-catalyzed [2+2] cycloaddition between N-sulfonylimines (2) and alkyl 2,3-butadienoate (3) afforded the (R)-azetidines 4 in excellent yields and enantioselectivities. The (S)-enantiomer was obtained when a quinine-amide c ...

Wiley-Blackwell2011

Synthesis of (E,Z)-1-Alkoxy-3-acyloxy-2-methylpenta-1,3-dienes via Danishefsky-Type Dienes or O-Acylation of Enones

Pierre Vogel, Maris Turks, Sylvain Claude Laclef, Claudia Jana Exner

1-Alkoxy-2-methyl-3-acyloxy-(E,E)-penta-1,3-dienes have been prepared applying among others a modified Danishefsky's general method, including chiral, racemic, and achiral derivatives. ...

2009

Enantiopure, supramolecular helices containing three-dimensional tetranuclear lanthanide(III) arrays: Synthesis, structure, properties, and solvent-driven Trinuclear/Tetranuclear interconversion

Marco Antonio Lama

The enantiomerically pure pinene-bipyridine-based receptor, (-) or (+) L-, diastereoselectively self-assembles in dry acetonitrile in the presence of Ln(III) ions (Ln = La, Pr, Nd, Sm, Eu, Gd, and Tb) to give a C-3-symmetrical, pyramidal architecture with ...

2008

Chiral recognition and supramolecular self-assembly of adsorbed amino acids and dipeptides at the submolecular level

Magalí Alejandra Lingenfelder

This thesis deals with the supramolecular organization of chiral aminoacids and dipeptides on metal surfaces. The emergence of homochirality in biomolecular systems is one of the most intriguing open questions of Nature. The self-assembly and amplification ...

EPFL2008

Selectivity of montmorillonite catalyzed prebiotic reactions of D, L-nucleotides

The montmorillonite-catalyzed reactions of the 5′-phosphorimidazolides of D, L-adenosine (D, L-ImpA) (Figure 1a. N = A, R = H) and D, L-uridine (Figure 1a., N = U, R = H) yields oligomers that were as long as 7 mers and 6 mers, respectively. The reactions ...

2007

Total asymmetric synthesis of (-)-conduramine B-1 and of its enantiomer. N-Benzyl derivatives of conduramine B-1 are beta-glucosidase inhibitors

Pierre Vogel

The 'naked sugars' (+)- and (-)-7-oxabicyclo[2.2.1]hept-5-en-2-one have been converted into (-)-conduramine B-1 ((-)3) and its enantiomer (+)-3, respectively. They have been condensed with a variety of aldehydes in the presence of NaBH(OAC)(3). The N-subst ...

2005

Enantioselective transformation of α-hexachlorocyclohexane by the dehydrochlorinases LinA1 and LinA2 from the soil bacterium Sphingomonas paucimobilis B90A

Christof Holliger, Vishakha Raina

Sphingomonas paucimobilis B90A contains two variants, LinA1 and LinA2, of a dehydrochlorinase that catalyzes the first and second steps in the metabolism of hexachlorocyclohexanes (R. Kumari, S. Subudhi, M. Suar, G. Dhingra, V. Raina, C. Dogra, S. Lal, J. ...

2005