scholarly journals 2-Azadienes as Enamine Umpolung Synthons for the Preparation of Chiral Amines

Synlett ◽  
2019 ◽  
Vol 30 (11) ◽  
pp. 1253-1268 ◽  
Author(s):  
Steven J. Malcolmson ◽  
Kangnan Li ◽  
Xinxin Shao
Keyword(s):  
Organic Synthesis ◽  
Metal Species ◽  
Chiral Amines ◽  
Chiral Amine ◽  
Tertiary Alcohols ◽  
Reductive Couplings ◽  
Benzylic Amines ◽  
Important Objective ◽  
New Strategies

The development of new strategies for the preparation of chiral amines is an important objective in organic synthesis. In this Synpacts, we summarize our approach for catalytically accessing nucleophilic aminoalkyl metal species from 2-azadienes, and its application in generating a number of important but elusive chiral amine scaffolds. Reductive couplings with ketones and imines afford 1,2-amino tertiary alcohols and 1,2-diamines, respectively, whereas fluoroarylations of gem-difluoro-2-azadienes deliver α-trifluoromethylated benzylic amines.1 Introduction2 Background: Umpolung Strategies for Preparing Chiral Amines3 Background: 2-Azadienes4 Reductive Couplings of 2-Azadienes5 Fluoroarylations of gem-Difluoro-2-azadienes6 Summary and Outlook

scholarly journals “Probe, Sample, and Instrument (PSI)”: The Hat-Trick for Fluorescence Live Cell Imaging

Chemosensors ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 40 ◽  
Author(s):  
Ludovic Galas ◽  
Thibault Gallavardin ◽  
Magalie Bénard ◽  
Arnaud Lehner ◽  
Damien Schapman ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Fluorescent Probes ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Live Cell ◽  
Cell Labeling ◽  
Key Points ◽  
Research Infrastructures ◽  
New Strategies ◽  
Fluorescence Live Cell Imaging

Cell Imaging Platforms (CIPs) are research infrastructures offering support to a number of scientific projects including the choice of adapted fluorescent probes for live cell imaging. What to detect in what type of sample and for how long is a major issue with fluorescent probes and, for this, the “hat-trick” “Probe–Sample–Instrument” (PSI) has to be considered. We propose here to deal with key points usually discussed in CIPs including the properties of fluorescent organic probes, the modality of cell labeling, and the best equipment to obtain appropriate spectral, spatial, and temporal resolution. New strategies in organic synthesis and click chemistry for accessing probes with enhanced photophysical characteristics and targeting abilities will also be addressed. Finally, methods for image processing will be described to optimize exploitation of fluorescence signals.

scholarly journals Parallel Interconnected Kinetic Asymmetric Transformation (PIKAT) with an Immobilized ω-Transaminase in Neat Organic Solvent

Molecules ◽  
2020 ◽  
Vol 25 (9) ◽  
pp. 2140 ◽  
Author(s):  
Wesley Böhmer ◽  
Lucien Koenekoop ◽  
Timothée Simon ◽  
Francesco G. Mutti
Keyword(s):  
Kinetic Resolution ◽  
Enantiomeric Excess ◽  
Molar Ratio ◽  
Chiral Amines ◽  
Aqueous Environment ◽  
Chiral Amine ◽  
Parallel Kinetic Resolution ◽  
Pharmaceutical Manufacture ◽  
Prochiral Ketones ◽  
Asymmetric Transformation

Comprising approximately 40% of the commercially available optically active drugs, α-chiral amines are pivotal for pharmaceutical manufacture. In this context, the enzymatic asymmetric amination of ketones represents a more sustainable alternative than traditional chemical procedures for chiral amine synthesis. Notable advantages are higher atom-economy and selectivity, shorter synthesis routes, milder reaction conditions and the elimination of toxic catalysts. A parallel interconnected kinetic asymmetric transformation (PIKAT) is a cascade in which one or two enzymes use the same cofactor to convert two reagents into more useful products. Herein, we describe a PIKAT catalyzed by an immobilized ω-transaminase (ωTA) in neat toluene, which concurrently combines an asymmetric transamination of a ketone with an anti-parallel kinetic resolution of an amine racemate. The applicability of the PIKAT was tested on a set of prochiral ketones and racemic α-chiral amines in a 1:2 molar ratio, which yielded elevated conversions (up to >99%) and enantiomeric excess (ee, up to >99%) for the desired products. The progress of the conversion and ee was also monitored in a selected case. This is the first report of a PIKAT using an immobilized ωTA in a non-aqueous environment.

New strategies in using macromolecular catalysts in organic synthesis

1992 ◽  
Vol 74 (1-3) ◽  
pp. 409-419 ◽  
Author(s):  
David E. Bergbreiter ◽  
Bushi Chen ◽  
David Weatherford
Keyword(s):  
Organic Synthesis ◽  
New Strategies

Development of a Hydrazine-Catalyzed Carbonyl-Olefin Metathesis Reaction

Synlett ◽  
2019 ◽  
Vol 30 (17) ◽  
pp. 1954-1965 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Double Bond ◽  
Organic Synthesis ◽  
Olefin Metathesis ◽  
Type I ◽  
Type Ii ◽  
Metathesis Reaction ◽  
Alternative Strategies ◽  
Potential Applications ◽  
Acid Catalyzed ◽  
New Strategies

Carbonyl-olefin metathesis is a potentially powerful yet underexplored reaction in organic synthesis. In recent years, however, this situation has begun to change, most notably with the introduction of several different catalytic technologies. The development of one of those new strategies, based on hydrazine catalysts and a novel [3+2] paradigm for double bond metathesis, is discussed herein. First, the stage is set with a description of some potential applications of carbonyl-olefin metathesis and a discussion of alternative strategies for this intriguing reaction.1 Introduction2 Potential Applications of Carbonyl-Olefin Metathesis3 Carbonyl-Olefin Metathesis Strategies4 Direct (Type I): Non-Catalytic5 Direct (Type I): Acid-Catalyzed6 Indirect (Type II): Metal Alkylidenes7 Indirect (Type III): Hydrazine-Catalyzed8 Conclusion

scholarly journals Tunable Supramolecular Chirogenesis in the Self-Assembling of Amphiphilic Porphyrin Triggered by Chiral Amines

2020 ◽  
Vol 21 (22) ◽  
pp. 8557
Author(s):  
Marco Savioli ◽  
Manuela Stefanelli ◽  
Gabriele Magna ◽  
Francesca Zurlo ◽  
Maria Federica Caso ◽  
...  
Keyword(s):  
Self Assembly ◽  
Hydrophobic Effect ◽  
The Self ◽  
Chiral Amines ◽  
Solvent Mixtures ◽  
Fractal Structures ◽  
Chiral Amine ◽  
Supramolecular Chirality ◽  
Self Assembling ◽  
Aqueous Solvent

Supramolecular chirality is one of the most important issues in different branches of science and technology, as stereoselective molecular recognition, catalysis, and sensors. In this paper, we report on the self-assembly of amphiphilic porphyrin derivatives possessing a chiral information on the periphery of the macrocycle (i.e., D- or L-proline moieties), in the presence of chiral amines as co-solute, such as chiral benzylamine derivatives. The aggregation process, steered by hydrophobic effect, has been studied in aqueous solvent mixtures by combined spectroscopic and topographic techniques. The results obtained pointed out a dramatic effect of these ligands on the morphology and on the supramolecular chirality of the final self-assembled structures. Scanning electron microscopy topography, as well as fluorescence microscopy studies revealed the formation of rod-like structures of micrometric size, different from the fractal structures formerly observed when the self-assembly process is carried out in the absence of chiral amine co-solutes. On the other hand, comparative experiments with an achiral porphyrin analogue strongly suggested that the presence of the prolinate moiety is mandatory for the achievement of the observed highly organized suprastructures. The results obtained would be of importance for unraveling the intimate mechanisms operating in the selection of the homochirality, and for the preparation of sensitive materials for the detection of chiral analytes, with tunable stereoselectivity and morphology.

Reduction of Oximes and Hydrazones: Asymmetric and Diastereoselective Approaches

2021 ◽  
Vol 25 ◽  
Author(s):  
João L. P. Ribeiro ◽  
Cláudia Alves ◽  
Ana L. Cardoso ◽  
Susana M. M. Lopes ◽  
Teresa M. V. D. Pinho e Melo
Keyword(s):  
Organic Synthesis ◽  
Asymmetric Reduction ◽  
Building Blocks ◽  
Electrochemical Reactions ◽  
Chiral Amines ◽  
Diastereoselective Reduction ◽  
Metal Catalyzed ◽  
Made In

: The asymmetric reduction of oximes and hydrazones is an attractive and versatile strategy for the synthesis of chiral amines, which are valuable building blocks in organic synthesis. This review summarizes the relevant developments made in the last decade on the enantioselective and diastereoselective reduction of oximes and hydrazones involving metal-catalyzed hydrogenation/hydrogenolysis reactions, hydride donor reactions, and electrochemical reactions.

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