scholarly journals Synthesis of novel 5-alkyl/aryl/heteroaryl substituted diethyl 3,4-dihydro-2H-pyrrole-4,4-dicarboxylates by aziridine ring expansion of 2-[(aziridin-1-yl)-1-alkyl/aryl/heteroaryl-methylene]malonic acid diethyl esters

2011 ◽  
Vol 7 ◽  
pp. 831-838 ◽  
Author(s):  
Satish S More ◽  
T Krishna Mohan ◽  
Y Sateesh Kumar ◽  
U K Syam Kumar ◽  
Navin B Patel
Keyword(s):  
Dicarboxylic Acid ◽  
Malonic Acid ◽  
Ring Expansion ◽  
Synthetic Methodology ◽  
Reaction Conditions ◽  
Alkyl Aryl ◽  
Aziridine Ring ◽  
Iodide Ion ◽  
Kinetics Of

A novel synthetic methodology has been developed for the synthesis of diethyl 5-alkyl/aryl/heteroaryl substituted 3,4-dihydro-2H-pyrrole-4,4-dicarboxylates (also called 2-substituted pyrroline-4,5-dihydro-3,3-dicarboxylic acid diethyl esters) by iodide ion induced ring expansion of 2-[(aziridin-1-yl)-1-alkyl/aryl/heteroaryl-methylene]malonic acid diethyl esters in very good to excellent yields under mild reaction conditions. The electronic and steric impact of the substituents on the kinetics of ring expansion of N-vinyl aziridines to pyrrolines has been studied. Various diversely substituted novel pyrroline derivatives have been synthesized by this methodology and the products can be used as key intermediates in the synthesis of substituted pyrrolines, pyrroles and pyrrolidines.

Effects of salts on the kinetics of oxidation of alkenes by thallic salts in aqueous solutions

1981 ◽  
Vol 46 (3) ◽  
pp. 693-700 ◽  
Author(s):  
Milan Strašák ◽  
Jaroslav Majer
Keyword(s):  
Aqueous Solutions ◽  
Phase Transfer ◽  
Heterogeneous Reaction ◽  
Qualitative Model ◽  
Kinetic Effect ◽  
Tetraalkylammonium Salts ◽  
Reaction Conditions ◽  
Kinetics Of Oxidation ◽  
Kinetics Of ◽  
Heterogeneous Reaction Conditions

The kinetics of oxidation of alkenes by thallic sulphate in aqueous solutions, involving the two reaction steps-the hydroxythallation and the dethallation - was studied, and the effect of salts on the kinetics was examined; this made it possible to specify more precisely the reaction mechanism and to suggest a qualitative model of the reaction coordinate. It was found that in homogeneous as well as in heterogeneous reaction conditions, the reaction can be accelerated appreciably by adding tetraalkylammonium salts. These salts not only operate as catalysts of the phase transfer, but also exert a significant kinetic effect, which can be explained with a simplification in terms of a stabilization of the transition state of the reaction.

Cleavage of the Epimines of 1,6-Anhydrohexoses with Fluoride Anion

2005 ◽  
Vol 70 (12) ◽  
pp. 2075-2085 ◽  
Author(s):  
Jiří Kroutil ◽  
Klára Jeništová
Keyword(s):  
Fluoride Anion ◽  
Ring Cleavage ◽  
Protecting Group ◽  
Reaction Conditions ◽  
Aziridine Ring ◽  
Cleavage Reactions ◽  
Derivatives Of ◽  
Fluoro Derivatives

Aziridine ring cleavage reactions of five N-nosylepimines (2-6) having D-talo, D-galacto, D-manno, and D-allo configurations with potassium hydrogendifluoride under various reaction conditions have been performed. The cleavage regioselectively afforded diaxial isomers of vicinal amino-fluoro derivatives of 1,6-anhydro-β-D-gluco- and mannopyranose 7-11 in 51-94% yields. Removal of 2-nitrobenzenesulfonyl protecting group with benzenethiol has been attempted in the case of compound 10.

scholarly journals A Novel Pseudomonas geniculata AGE Family Epimerase/Isomerase and Its Application in d-Mannose Synthesis

Foods ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1809
Author(s):  
Zhanzhi Liu ◽  
Ying Li ◽  
Jing Wu ◽  
Sheng Chen
Keyword(s):  
3D Structure ◽  
Three Dimensional ◽  
Optimal Temperature ◽  
Reaction Conditions ◽  
Enzymatic Production ◽  
Physiological Properties ◽  
Potential Applications ◽  
Kinetics Of ◽  
Optimal Reaction ◽  
Gene Age

d-mannose has exhibited excellent physiological properties in the food, pharmaceutical, and feed industries. Therefore, emerging attention has been applied to enzymatic production of d-mannose due to its advantage over chemical synthesis. The gene age of N-acetyl-d-glucosamine 2-epimerase family epimerase/isomerase (AGEase) derived from Pseudomonas geniculata was amplified, and the recombinant P. geniculata AGEase was characterized. The optimal temperature and pH of P. geniculata AGEase were 60 °C and 7.5, respectively. The Km, kcat, and kcat/Km of P. geniculata AGEase for d-mannose were 49.2 ± 8.5 mM, 476.3 ± 4.0 s−1, and 9.7 ± 0.5 s−1·mM−1, respectively. The recombinant P. geniculata AGEase was classified into the YihS enzyme subfamily in the AGE enzyme family by analyzing its substrate specificity and active center of the three-dimensional (3D) structure. Further studies on the kinetics of different substrates showed that the P. geniculata AGEase belongs to the d-mannose isomerase of the YihS enzyme. The P. geniculata AGEase catalyzed the synthesis of d-mannose with d-fructose as a substrate, and the conversion rate was as high as 39.3% with the d-mannose yield of 78.6 g·L−1 under optimal reaction conditions of 200 g·L−1d-fructose and 2.5 U·mL−1P. geniculata AGEase. This novel P. geniculata AGEase has potential applications in the industrial production of d-mannose.

Synthesis of Pyrrolo[1,2-a][1,6]- and [1,8]naphthyridines by Alkyne-Carbonyl Metathesis

Synthesis ◽  
2020 ◽  
Author(s):  
Peter Ehlers ◽  
Peter Langer ◽  
Marian Blanco Ponce ◽  
Silvio Parpart ◽  
Alexander Villinger ◽  
...  
Keyword(s):  
Heterocyclic Compounds ◽  
Metathesis Reaction ◽  
Synthetic Methodology ◽  
Facile Synthesis ◽  
Reaction Conditions ◽  
One Pot ◽  
Metal Free ◽  
Modular Synthesis

AbstractA concise and modular synthesis of pyrrolo[1,2-a][1,6]- and [1,8]naphthyridines by a one-pot two-step reaction consisting of electrophilic acylation followed by an alkyne-carbonyl-metathesis reaction as the final cyclization step is reported. This developed synthetic methodology allows the facile synthesis of these heterocyclic core structures in mainly high overall yields under metal-free conditions. Reaction conditions are carefully optimized and display a novel supplement to access these tricyclic heterocyclic compounds.

Effect of Reaction Conditions on the Kinetics of Living Isobutylene Polymerization at High Initiator/TiCl4Ratios

2000 ◽  
Vol 33 (13) ◽  
pp. 4634-4638 ◽  
Author(s):  
C. Paulo ◽  
J. E. Puskas ◽  
S. Angepat
Keyword(s):  
Reaction Conditions ◽  
Kinetics Of

Aziridine ring expansion sequences

Tetrahedron ◽  
1974 ◽  
Vol 30 (16) ◽  
pp. 2613-2621 ◽  
Author(s):  
A. Hassner ◽  
Susan S. Burke
Keyword(s):  
Ring Expansion ◽  
Aziridine Ring

scholarly journals Intermolecular 3+3 Ring Expansion of Aziridines to Dehydropiperidines through the Intermediacy of Aziridinium Ylides

2019 ◽  
Author(s):  
Jennifer Schomaker ◽  
Josephine Eshon ◽  
Kate A. Nicastri ◽  
Steven C. Schmid ◽  
William T. Raskopf ◽  
...  
Keyword(s):  
Natural Product ◽  
Functional Group ◽  
Ring Expansion ◽  
Sigmatropic Rearrangement ◽  
Reactive Intermediate ◽  
Mechanistic Studies ◽  
Reaction Conditions ◽  
Complex Molecules ◽  
Form Complex ◽  
Reaction Proceeds

Bicyclic aziridines undergo formal [3+3] ring expansion reactions when exposed to rhodium-bound vinyl carbenes to form complex dehydropiperidines in a highly stereocontrolled rearrangement. Mechanistic studies and DFT computations indicate the reaction proceeds through the formation of a vinyl aziridinium ylide; this reactive intermediate undergoes a concerted, asynchronous, pseudo-[1,4]- sigmatropic rearrangement to directly furnish the heterocyclic products with net retention at the new C-C bond. In combination with an asymmetric silver-catalyzed aziridination developed in our group, this method quickly delivers enantioenriched scaffolds with up to three contiguous stereocenters. The mild reaction conditions, functional group tolerance, and high stereochemical retention of this method are especially well-suited for appending piperidine motifs to natural product and complex molecules. Ultimately, our work establishes the value of underutilized aziridinium ylides as key intermediates in strategies to convert small, strained rings to larger N-heterocycles.

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