scholarly journals Solvent-Free Ring Cleavage Hydrazinolysis of Certain Biginelli Pyrimidines

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Mohamed A. Said ◽  
Wagdy M. Eldehna ◽  
Hazem A. Ghabbour ◽  
Maha M. Kabil ◽  
Nasser S. Al-shakliah ◽  
...  
Keyword(s):  
Hydrazine Hydrate ◽  
Ring Opening ◽  
Solvent Free ◽  
Nucleophilic Attack ◽  
Ring Cleavage ◽  
Amino Group ◽  
Free Ring ◽  
Terminal Amino ◽  
Solvent Free Reaction

Certain Biginelli pyrimidines with ester substitution in C5 were subjected to unexpected ring opening upon solvent-free reaction with hydrazine hydrate to give three products: pyrazole, arylidenehydrazines, and urea/thiourea, respectively. The nonisolable carbohydrazide intermediates are formed firstly followed by the intermolecular nucleophilic attack of terminal amino group of hydrazide function on sp2 C6 rather than the sp3 C4 to give the ring adduct which was produced as a final product.

scholarly journals Low-temperature and purification-free stereocontrolled ring-opening polymerisation of lactide in supercritical carbon dioxide

2020 ◽  
Vol 22 (7) ◽  
pp. 2197-2202 ◽  
Author(s):  
Simon P. Bassett ◽  
Andrew D. Russell ◽  
Paul McKeown ◽  
Isabel Robinson ◽  
Thomas R. Forder ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Low Temperature ◽  
Supercritical Carbon Dioxide ◽  
Ring Opening ◽  
Solvent Free ◽  
Free Ring ◽  
First Time ◽  
Supercritical Carbon

A stereoselective, solvent-free ring-opening polymerisation (ROP) of lactide (LA) in supercritical carbon dioxide (scCO2) is reported for the first time.

Nonmetal Schiff-Base Complex-Anchored Cellulose as a Novel and Reusable Catalyst for the Solvent-Free Ring-Opening Addition of CO2 with Epoxides

2019 ◽  
Vol 58 (37) ◽  
pp. 17255-17265 ◽  
Author(s):  
Shiyu Chen ◽  
Manoj Pudukudy ◽  
Zhongxiao Yue ◽  
Heng Zhang ◽  
Yunfei Zhi ◽  
...  
Keyword(s):  
Schiff Base ◽  
Ring Opening ◽  
Schiff Base Complex ◽  
Solvent Free ◽  
Reusable Catalyst ◽  
Free Ring ◽  
Base Complex

scholarly journals SnCl4-catalyzed Solvent-free Acetolysis of 2,7-Anhydrosialic Acid Derivatives

2019 ◽  
Author(s):  
Kesatebrhan Haile Asressu ◽  
Cheng-Chung Wang
Keyword(s):  
Sialic Acid ◽  
Lewis Acids ◽  
Ring Opening ◽  
Building Blocks ◽  
Solvent Free ◽  
Biologically Active ◽  
Protecting Group ◽  
Free Ring ◽  
Ring Opening Reactions ◽  
Acid Catalyzed

Sialic acid-containing glycans are found in different sialic acid forms and a variety of glycosidic linkages in biologically active glycoconjugates. Hence, the preparation of suitably protected sialyl building blocks requires high attention in order to access glycans in pure form. In this line, various C-5 substituted 2,7-anhydrosialic acid derivatives bearing both electron donating and withdrawing protecting groups were synthesized and subjected to different Lewis acid-catalyzed solvent free ring opening reactions at room temperature in the presence of acetic anhydride. Among the various Lewis acids tested, the desired acetolysized products were obtained in moderate yields under a tin(IV) chloride catalysis system. Our methodology can be extended to regioselective protecting group installation and manipulation towards a number of thiosialoside and halide donors.

Coumarin salen-based zinc complex for solvent-free ring opening polymerization of ε-caprolactone

2017 ◽  
Vol 58 (10) ◽  
pp. 977-980 ◽  
Author(s):  
Nelson Nuñez-Dallos ◽  
Andrés F. Posada ◽  
John Hurtado
Keyword(s):  
Ring Opening ◽  
Zinc Complex ◽  
Ring Opening Polymerization ◽  
Solvent Free ◽  
Free Ring

Highly active and stereoselective zirconium and hafnium alkoxide initiators for solvent-free ring-opening polymerization of rac-lactide

2008 ◽  
pp. 1293 ◽  
Author(s):  
Amanda J. Chmura ◽  
Matthew G. Davidson ◽  
Catherine J. Frankis ◽  
Matthew D. Jones ◽  
Matthew D. Lunn
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Solvent Free ◽  
Free Ring ◽  
Highly Active

Solvent-Free Ring-Opening Metathesis Polymerization of Norbornene over Silica-Supported Tungsten-Oxo Perhydrocarbyl Catalysts

2016 ◽  
Vol 37 (22) ◽  
pp. 1832-1836 ◽  
Author(s):  
Cherif Larabi ◽  
Kai C. Szeto ◽  
Yassine Bouhoute ◽  
Marc O. Charlin ◽  
Nicolas Merle ◽  
...  
Keyword(s):  
Ring Opening ◽  
Solvent Free ◽  
Ring Opening Metathesis Polymerization ◽  
Free Ring ◽  
Metathesis Polymerization
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