scholarly journals Investigations towards the stereoselective organocatalyzed Michael addition of dimethyl malonate to a racemic nitroalkene: possible route to the 4-methylpregabalin core structure

2018 ◽  
Vol 14 ◽  
pp. 553-559 ◽  
Author(s):  
Denisa Vargová ◽  
Rastislav Baran ◽  
Radovan Šebesta
Keyword(s):  
Michael Addition ◽  
Kinetic Resolution ◽  
Stereoselective Synthesis ◽  
Core Structure ◽  
Aminobutyric Acid ◽  
Dimethyl Malonate ◽  
Michael Adduct ◽  
Michael Additions ◽  
Derivatives Of

Chiral derivatives of γ-aminobutyric acid are widely used as medicines and can be obtained by organocatalytic Michael additions. We show here the stereoselective synthesis of 4-methylpregabalin stereoisomers using a Michael addition of dimethyl malonate to a racemic nitroalkene. The key step of the synthesis operates as a kinetic resolution with a chiral squaramide catalyst. Furthermore, specific organocatalysts can provide respective stereoisomers of the key Michael adduct in up to 99:1 er.

Phosphazene Base-Catalyzed Double Michael Addition: Stereoselective Synthesis of Cyclohexanones

2018 ◽  
Vol 16 (1) ◽  
pp. 76-80
Author(s):  
Yang-Guo Li ◽  
Yang Zhang ◽  
Guang-Fen Du ◽  
Cheng-Zhi Gu ◽  
Lin He
Keyword(s):  
Michael Addition ◽  
Stereoselective Synthesis ◽  
Michael Additions

Phosphazene bases have been utilized as efficient organocatalysts to catalyze the double Michael additions of divinyl ketones with active methylenes to afford functionalized cyclohexanones in 36-91% yields with >25:1 diastereoselectivity.

Enantioselective Michael Addition of Malonates to Enones

2020 ◽  
Vol 24 (7) ◽  
pp. 746-773
Author(s):  
Péter Bakó ◽  
Tamás Nemcsok ◽  
Zsolt Rapi ◽  
György Keglevich
Keyword(s):  
Michael Addition ◽  
Activity Relationship ◽  
Chalcone Derivatives ◽  
Michael Additions ◽  
Michael Reactions ◽  
Structure Activity ◽  
Cyclic Enones ◽  
Michael Acceptors ◽  
Relationship Of ◽  
Enantioselective Catalysts

: Many catalysts were tested in asymmetric Michael additions in order to synthesize enantioenriched products. One of the most common reaction types among the Michael reactions is the conjugated addition of malonates to enones making it possible to investigate the structure–activity relationship of the catalysts. The most commonly used Michael acceptors are chalcone, substituted chalcones, chalcone derivatives, cyclic enones, while typical donors may be dimethyl, diethyl, dipropyl, diisopropyl, dibutyl, di-tert-butyl and dibenzyl malonates. This review summarizes the most important enantioselective catalysts applied in these types of reactions.

scholarly journals Recoverable Phospha-Michael Additions Catalyzed by a 4-N,N-Dimethylaminopyridinium Saccharinate Salt or a Fluorous Long-Chained Pyridine: Two Types of Reusable Base Catalysts

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1159
Author(s):  
Eskedar Tessema ◽  
Vijayanath Elakkat ◽  
Chiao-Fan Chiu ◽  
Jing-Hung Zheng ◽  
Ka Long Chan ◽  
...  
Keyword(s):  
Michael Addition ◽  
Polar Solvent ◽  
Addition Reaction ◽  
High Yield ◽  
Addition Reactions ◽  
Polar Solvents ◽  
Unsaturated Bond ◽  
Base Catalysts ◽  
Michael Additions

Phospha-Michael addition, which is the addition reaction of a phosphorus-based nucleophile to an acceptor-substituted unsaturated bond, certainly represents one of the most versatile and powerful tools for the formation of P-C bonds, since many different electrophiles and P nucleophiles can be combined with each other. This offers the possibility to access many diversely functionalized products. In this work, two kinds of basic pyridine-based organo-catalysts were used to efficiently catalyze phospha-Michael addition reactions, the 4-N,N-dimethylaminopyridinium saccharinate (DMAP·Hsac) salt and a fluorous long-chained pyridine (4-Rf-CH2OCH2-py, where Rf = C11F23). These catalysts have been synthesized and characterized by Lu’s group. The phospha-Michael addition of diisopropyl, dimethyl or triethyl phosphites to α, β-unsaturated malonates in the presence of those catalysts showed very good reactivity with high yield at 80–100 °C in 1–4.5 h with high catalytic recovery and reusability. With regard to significant catalytic recovery, sometimes more than eight cycles were observed for DMAP·Hsac adduct by using non-polar solvents (e.g., ether) to precipitate out the catalyst. In the case of the fluorous long-chained pyridine, the thermomorphic method was used to efficiently recover the catalyst for eight cycles in all the reactions. Thus, the easy separation of the catalysts from the products revealed the outstanding efficacy of our systems. To our knowledge, these are good examples of the application of recoverable organo-catalysts to the DMAP·Hsac adduct by using non-polar solvent and a fluorous long-chained pyridine under the thermomorphic mode in phospha-Michael addition reactions.

Chemoselective Double Michael Addition: Synthesis of 2,6-Diarylspiro[Cyclohexane-1,3′-Indoline]-2′,4-Diones via Addition of Indolin-2-One to Divinyl Ketones

2017 ◽  
Vol 41 (3) ◽  
pp. 168-171 ◽  
Author(s):  
Zheng Li ◽  
Jiasheng Li ◽  
Jingya Yang
Keyword(s):  
Michael Addition ◽  
High Yield ◽  
Reaction Conditions ◽  
Michael Additions

Seventeen examples of 2,6-diarylspiro[cyclohexane-1,3′-indoline]-2′4-diones were efficiently prepared by the Cs2CO3-catalysed chemoselective double Michael additions of indolin-2-one to divinyl ketones. This method has the advantage of high chemoselectivity, mild reaction conditions, high yield and atom- and step-economy.

ChemInform Abstract: A Facile and Efficient Stereoselective Synthesis of Highly Functionalized Trisubstituted Alkene Derivatives of Ferrocenealdehyde.

ChemInform ◽  
2008 ◽  
Vol 39 (15) ◽  
Author(s):  
Ponnusamy Shanmugam ◽  
Vadivel Vaithiyanathan ◽  
Baby Viswambharan ◽  
Suchithra Madhavan
Keyword(s):  
Stereoselective Synthesis ◽  
Derivatives Of

scholarly journals A Versatile Method for Preparing Polysaccharide Conjugates via Thiol-Michael Addition

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1905
Author(s):  
Junyi Chen ◽  
Xutao Ma ◽  
Kevin J. Edgar
Keyword(s):  
Michael Addition ◽  
Quaternary Ammonium ◽  
Synthetic Approach ◽  
Renewable Materials ◽  
Fast Reaction ◽  
Michael Additions ◽  
Antimicrobial Performance ◽  
A Charge ◽  
Post Modification ◽  
Fast Reaction Rate

Polysaccharide conjugates are important renewable materials. If properly designed, they may for example be able to carry drugs, be proactive (e.g., with amino acid substituents) and can carry a charge. These aspects can be particularly useful for biomedical applications. Herein, we report a simple approach to preparing polysaccharide conjugates. Thiol-Michael additions can be mild, modular, and efficient, making them useful tools for post-modification and the tailoring of polysaccharide architecture. In this study, hydroxypropyl cellulose (HPC) and dextran (Dex) were modified by methacrylation. The resulting polysaccharide, bearing α,β-unsaturated esters with tunable DS (methacrylate), was reacted with various thiols, including 2-thioethylamine, cysteine, and thiol functional quaternary ammonium salt through thiol-Michael addition, affording functionalized conjugates. This click-like synthetic approach provided several advantages including a fast reaction rate, high conversion, and the use of water as a solvent. Among these polysaccharide conjugates, the ones bearing quaternary ammonium salts exhibited competitive antimicrobial performance, as supported by a minimum inhibitory concentration (MIC) study and tracked by SEM characterization. Overall, this methodology provides a versatile route to polysaccharide conjugates with diverse functionalities, enabling applications such as antimicrobial activity, gene or drug delivery, and biomimicry.

Sign in / Sign up

Export Citation Format

Share Document