نتایج جستجو برای: organocatalysis

تعداد نتایج: 465  

Journal: :Science 2008
David A Nicewicz David W C MacMillan

Photoredox catalysis and organocatalysis represent two powerful fields of molecule activation that have found widespread application in the areas of inorganic and organic chemistry, respectively. We merged these two catalysis fields to solve problems in asymmetric chemical synthesis. Specifically, the enantioselective intermolecular alpha-alkylation of aldehydes has been accomplished using an i...

2012
Chittaranjan Bhanja Satyaban Jena Sabita Nayak Seetaram Mohapatra

Enantioselective organocatalysis has become a field of central importance within asymmetric chemical synthesis and appears to be efficient approach toward the construction of complex chiral molecules from simple achiral materials in one-pot transformations under mild conditions with high stereocontrol. This review addresses the most significant synthetic methods reported on chiral-amine-catalyz...

Journal: :Organic & biomolecular chemistry 2011
Ernest Owusu-Ansah Amanda C Durow John R Harding Angela C Jordan Susan J O'Connell Christine L Willis

(S)-4,4-Dichloro-3-methylbutanoic acid was prepared in 51% overall yield from commercially available starting materials using an organocatalytic transfer hydrogenation to 4,4-dichloro-3-methylbut-2-enal in the key step. The (S)-dichloro acid was used as an intermediate in the first total synthesis of dysideaproline E and a diastereomer confirming the structure of the natural product.

2012
Herbert Mayr Sami Lakhdar Biplab Maji Armin R Ofial

The key steps in most organocatalytic cyclizations are the reactions of electrophiles with nucleophiles. Their rates can be calculated by the linear free-energy relationship log k(20 °C) = s(N)(E + N), where electrophiles are characterized by one parameter (E) and nucleophiles are characterized by the solvent-dependent nucleophilicity (N) and sensitivity (s(N)) parameters.Electrophilicity param...

Journal: :Catalysts 2023

The global E factor (EG factor) has recently been introduced, in the context of asymmetric organocatalysis, as a new green chemistry metric to take into consideration synthesis catalyst overall economy synthetic process given chiral molecule optically pure form. Herein, its further usefulness comparing diverse catalytic systems, even different from organocatalysts, is shown by analysis four cas...

Journal: :Advanced Synthesis & Catalysis 2021

The electrochemical generation of N-heterocyclic carbenes (NHCs) offers a mild and selective alternative to traditional synthetic methods that usually rely on strong bases air-sensitive materials. use electrons as reagents results in an efficient clean synthesis enables the direct NHCs various applications. Herein, electrogenerated organocatalysis, organometallic chemistry is explored.

Journal: :Journal of photochemistry and photobiology. B, Biology 2015
Oana R Luca Aidan Q Fenwick

The present review covers organic transformations involved in the reduction of CO2 to chemical fuels. In particular, we focus on reactions of CO2 with organic molecules to yield carboxylic acid derivatives as a first step in CO2 reduction reaction sequences. These biomimetic initial steps create opportunities for tandem electrochemical/chemical reductions. We draw parallels between long-standin...

Journal: :Organic & biomolecular chemistry 2013
Yoshihiro Sohtome Takahisa Yamaguchi Shinji Tanaka Kazuo Nagasawa

Here we describe our studies on solvent-dependent enantiodivergent Mannich-type reactions utilizing conformationally flexible guanidine/bisthiourea organocatalyst (S,S)-1. Our mechanistic investigations revealed that the stereo-determining steps in both the (R)- and (S)-selective Mannich-type reactions are governed by the cooperative effect of guanidine and thiourea in the inherently monomeric ...

2016
Giorgos Koutoulogenis Nikolaos Kaplaneris Christoforos G Kokotos

Organocatalysis, now running its second decade of life, is being considered one of the main tools a synthetic chemist has to perform asymmetric catalysis. In this review the synthesis of six-membered rings, that contain multiple chiral centers, either by a ring closing process or by a functionalization reaction on an already existing six-membered ring, utilizing bifunctional (thio)ureas will be...

Journal: :Organic & biomolecular chemistry 2017
J Schmauck M Breugst

Pnicogen bonding is a noncovalent interaction between the electrophilic region of a phosphorus atom and a Lewis base. Although this interaction can be comparable in strength to other noncovalent interactions, no systematic application in organic synthesis or catalysis is known so far. To identify the potential of this interaction for organocatalysis, we have now analysed different pnicogen-bond...

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