scholarly journals NHC-catalyzed covalent activation of heteroatoms for enantioselective reactions

2021 ◽  
Vol 12 (14) ◽  
pp. 5037-5043
Author(s):  
Runjiang Song ◽  
Zhichao Jin ◽  
Yonggui Robin Chi
Keyword(s):  
Enantioselective Reactions ◽  
Covalent Activation ◽  
Organic Catalysts

Covalent activation of heteroatoms enabled by N-heterocyclic carbene (NHC) organic catalysts for enantioselective reactions is evaluated and summarized in this review.

Strategies of In Situ Generated Magnesium Catalysis in Asymmetric Reactions

Synlett ◽  
2021 ◽  
Author(s):  
Dongxu Yang ◽  
Linqing Wang
Keyword(s):  
Asymmetric Synthesis ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Asymmetric Reactions ◽  
Chiral Ligands ◽  
Alkaline Earth Metal ◽  
Enantioselective Reactions ◽  
Earth's Crust

AbstractMagnesium (Mg) is a cheap, non-toxic, and recyclable alkaline earth metal that constitutes about 2% weight in the Earth’s crust. The use of magnesium catalysts to forge chiral moieties in molecules is highly attractive. Based on our work in recent years, we describe the current progress in the development of in situ generated magnesium catalysts and their application in asymmetric synthesis. In this perspective, a critically concise classification of in situ generated magnesium catalytic modes, with relevant examples, is presented, and representative mechanisms of each category are discussed. Building on the established diverse strategies, one can foresee that more innovative and structurally creative magnesium catalysts that are generated in situ will be developed to overcome more formidable challenges of catalytic enantioselective reactions.1 Introduction2 Magnesium Catalysts Generated in Situ from Chiral Ligands Containing Dual Reactive Hydrogens3 Magnesium Catalysts Generated in Situ from Monoanionic Chiral Ligands4 Bimetallic and Polymetallic Magnesium Catalysts Assembled in Situ5 Summary and Outlook

Enantioselective reactions of radicals at the α position of γ-lactams

1999 ◽  
Vol 40 (37) ◽  
pp. 6713-6716 ◽  
Author(s):  
Ned A. Porter ◽  
Hao Feng ◽  
Ivanka K. Kavrakova
Keyword(s):  
Enantioselective Reactions

scholarly journals Lactones in the Synthesis of Prostaglandins and Prostaglandin Analogs

2021 ◽  
Vol 22 (4) ◽  
pp. 1572
Author(s):  
Constantin Tănase ◽  
Lucia Pintilie ◽  
Raluca Elena Tănase
Keyword(s):  
Biological Role ◽  
Controlled Synthesis ◽  
Side Chains ◽  
Enzymatic Resolution ◽  
Marine Mollusc ◽  
Enantioselective Reactions ◽  
The Many ◽  
Key Steps

In the total stereo-controlled synthesis of natural prostaglandins (PGs) and their structural analogs, a vast class of compounds and drugs, known as the lactones, are encountered in a few key steps to build the final molecule, as: δ-lactones, γ-lactones, and 1,9-, 1,11-, and 1,15-macrolactones. After the synthesis of 1,9-PGF2α and 1,15-PGF2α lactones, many 1,15-lactones of E2, E3, F2, F3, A2, and A3 were found in the marine mollusc Tethys fimbria and the quest for understanding their biological role stimulated the research on their synthesis. Then 1,9-, 1,11-, and 1,15-PG lactones of the drugs were synthesized as an alternative to the corresponding esters, and the first part of the paper describes the methods used for their synthesis. The efficient Corey procedure for the synthesis of prostaglandins uses the key δ-lactone and γ-lactone intermediates with three or four stereocenters on the cyclopentane fragment to link the PG side chains. The paper describes the most used procedures for the synthesis of the milestone δ-Corey-lactones and γ-Corey-lactones, their improvements, and some new promising methods, such as interesting, new stereo-controlled and catalyzed enantioselective reactions, and methods based on the chemical/enzymatic resolution of the compounds in different steps of the sequences. The many uses of δ-lactones not only for the synthesis of γ-lactones, but also for obtaining 9β-halogen-PGs and halogen-substituted cyclopentane intermediates, as synthons for new 9β-PG analogs and future applications, are also discussed.

The Mode of Action of Disulfide Accelerators of Vulcanization

1937 ◽  
Vol 10 (1) ◽  
pp. 158-163
Author(s):  
W. Langenbeck ◽  
H. C. Rhiem
Keyword(s):  
Organic Compounds ◽  
Mode Of Action ◽  
Common Knowledge ◽  
Inorganic Compounds ◽  
Technical Problem ◽  
The Other ◽  
Rubber Industry ◽  
Organic Catalysis ◽  
Catalytic Power ◽  
Organic Catalysts

Abstract The catalytic power of organic compounds in general has up to the present time been studied much less extensively than that of inorganic compounds. For about the last ten years, however, the first author has, in collaboration with a number of his students, attempted to fill this gap, though so far efforts have been confined to explaining the mode of action of natural enzymes by means of comparative experiments with organic catalysts. As a result of this work, a theory based on experimental facts has been developed to explain in a satisfactory way the action of enzymes. The other phase of organic catalysis is, strictly speaking, a technical problem. Why for instance should it not be practicable to utilize organic catalysts more extensively than heretofore in industry? If this problem is to be attacked, it seems reasonable to start with the particular industry which already uses organic catalysts to the greatest extent. This is, of course, the rubber industry. The important accomplishments of the chemical industry with respect to the development of vulcanization accelerators is already common knowledge, and the important task at present is not simply to increase the great number of accelerators already known. A problem of more practical value would seem to be to study the mechanism of the acceleration of vulcanization, about which relatively little has been known heretofore.

Enhanced Activity and Stereoselectivity of Polystyrene-Supported Proline-Based Organic Catalysts for Direct Asymmetric Aldol Reaction in Water

2009 ◽  
Vol 2009 (31) ◽  
pp. 5437-5444 ◽  
Author(s):  
Michelangelo Gruttadauria ◽  
Anna Maria Pia Salvo ◽  
Francesco Giacalone ◽  
Paola Agrigento ◽  
Renato Noto
Keyword(s):  
Aldol Reaction ◽  
Asymmetric Aldol ◽  
Enhanced Activity ◽  
Asymmetric Aldol Reaction ◽  
Reaction In Water ◽  
Organic Catalysts

Ring-Opening Copolymerization Using Simple Fe(III) Complexes and Metal- and Halide-Free Organic Catalysts

2021 ◽  
Vol 54 (18) ◽  
pp. 8443-8452
Author(s):  
Oliver J. Driscoll ◽  
Jack A. Stewart ◽  
Paul McKeown ◽  
Matthew D. Jones
Keyword(s):  
Ring Opening ◽  
Organic Catalysts
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