Search results for "organocatalysi"

Asymmetric Synthesis of Dihydropyranones with Three Contiguous Stereocenters by an NHC‐Catalyzed Kinetic Resolution

2021

An oxidative NHC-catalyzed kinetic resolution (KR) of racemic mixtures is presented. The developed reaction furnishes tricyclic dihydropyranones with three contiguous stereocenters in excellent dia- and enantioselectivity, with good-to-moderate yields. Mechanistic studies indicate that the rate-determining step of the reaction is the formation of the Breslow intermediate, while the selectivity determining step occurs later in the mechanism. The presented methodology enables rapid synthesis of complex structures in a single step.

Asymmetric Methods for Carbon‐Fluorine Bond Formation

2021

Catalysis in Supramolecular Systems: the Case of Gel Phases

2021

Supramolecular gels are a fascinating class of materials, originated by the self-assembly of low molecular weight molecules. Underpinned by non-covalent interactions, they find application in a diverse range of fields. Among these, supramolecular gels can be considered as organized, non-conventional reaction media, able to influence reactivity in a radically different way, compared with what happens in solution. This short review will focus on this aspect, covering literature from 2010 onwards, addressing the application of supramolecular gels as reaction media. In particular, in the first section we explore organocatalytic reactions in gel phase, with wide synthetic relevance, such as aldo…

ChemInform Abstract: Supported Proline and Proline-Derivatives as Recyclable Organocatalysts

2008

In the last eight years, L-proline and L-proline derivatives, such as substituted prolinamides or pyrrolidines, have been successfully used as organocatalysts in several reactions. In this critical review we summarize the immobilization procedures of such organocatalysts highlighting their application, recoverability and reusability (86 references).

Catalytic Enantioselective α-Oxysulfonylation of Ketones Mediated by Iodoarenes

2008

The alpha-oxysulfonylation of ketones catalysed by enantioenriched iodoarenes using mCPBA as stoichiometric oxidant is reported to give useful synthetic intermediates in good yield and modest enantioselectivity. We believe this to be the first report of an enantioselective organocatalytic reaction involving hypervalent iodine reagents which should open up a new field for enantioselective organocatalysis of oxidation reactions.

A Liquid-Liquid Biphasic Homogeneous Organocatalytic Aldol Protocol Based on the Use of a Silica Gel Bound Multilayered Ionic Liquid Phase

2012

An innovative two stage liquid–liquid biphasic homogeneous protocol for the asymmetric organocatalytic aldol reaction is proposed, based on the use of the cis-ion-tagged proline 8 dissolved in the liquid film of a multilayered ionic liquid covalently bonded to silica gel 4. The resulting catalytically active material 9 is first soaked with cyclohexanone in the presence of water, resulting in a semi-transparent gel, then the aldehyde is added and the mixture stirred at RT. In the first stage, 4 acts as a catalyst reservoir that delivers 8 to the cyclohexanone phase allowing the reaction to take place homogeneously. In the second stage, cyclohexanone is removed under vacuum and the resulting …

Organocatalytic Enantioselective Intramolecular (Hetero)Michael Additions in Desymmetrization Processes

2021

ChemInform Abstract: Designing P*-Chirogenic Organophosphorus Compounds: From Ligands to Organocatalysts

2015

The interest of organophosphorus compounds bearing chirality on the phosphorus atom has greatly expanded in last decade, due to the development of efficient stereoselective synthetic methods, using...

Nitroenynes as Electrophiles in Organocatalysis and their Application in the Synthesis of Chiral Heterocycles

2021

Nitroenynes are an interesting electrophile in asymmetric organocatalysis, due to the versatility of the functional groups present in its structure. This review covers the organocatalytic examples using this electrophile and its application for the synthesis of chiral heterocycles.

Recent Advances in Catalytic Enantioselective Synthesis of Pyrazolones with a Tetrasubstituted Stereogenic Center at the 4-Position

2020

AbstractPyrazolone [2,4-dihydro-3H-pyrazol-4-one] represents one of the most important five-membered nitrogen heterocycles which is present in numerous pharmaceutical drugs and molecules with biological activity. Recently, many catalytic methodologies for the asymmetric synthesis of chiral pyrazolones have been established with great success, specially, for the synthesis of pyrazolones bearing a tetrasubstituted stereocenter at C-4. This review summarizes these excellent research studies since 2018, including representative examples and some mechanistic pathways explaining the observed stereochemistry.1 Introduction2 Catalytic Enantioselective Synthesis of Chiral Pyrazolones with a Full Car…