Anionic Fries rearrangement of aryl carbonates. A facile route to ortho-hydroxy esters

2020 ◽  
Vol 61 (45) ◽  
pp. 152488
Author(s):  
Aleksei V. Ananin ◽  
George A. Kraus
Keyword(s):  
Fries Rearrangement ◽  
Hydroxy Esters ◽  
Facile Route

ChemInform Abstract: Anionic ortho-Fries Rearrangement, a Facile Route to Arenol-Based Mannich Bases.

ChemInform ◽  
2010 ◽  
Vol 41 (9) ◽  
Author(s):  
Nikos Assimomytis ◽  
Yiannis Sariyannis ◽  
Georgios Stavropoulos ◽  
Petros G. Tsoungas ◽  
George Varvounis ◽  
...  
Keyword(s):  
Mannich Bases ◽  
Fries Rearrangement ◽  
Facile Route

Anionic ortho-Fries Rearrangement, a Facile Route to Arenol-Based Mannich Bases

Synlett ◽  
2009 ◽  
Vol 2009 (17) ◽  
pp. 2777-2782 ◽  
Author(s):  
Petros Tsoungas ◽  
Nikos Assimomytis ◽  
Yiannis Sariyannis ◽  
Georgios Stavropoulos ◽  
George Varvounis ◽  
...  
Keyword(s):  
Mannich Bases ◽  
Fries Rearrangement ◽  
Facile Route

4-Hydroxy Pyridinium Triflate@SiO2 Nanoparticles as a Novel Efficient Catalyst for Fries Rearrangement of Aryl Esters with High Selectivity

2020 ◽  
Vol 17 (8) ◽  
pp. 654-660
Author(s):  
Shermineh Sadat Ghalehbandi ◽  
Dadkhoda Ghazanfari ◽  
Sayed Ali Ahmadi ◽  
Enayatollah Sheikhhosseini
Keyword(s):  
High Selectivity ◽  
Sio2 Nanoparticles ◽  
High Yield ◽  
Synthetic Method ◽  
Functionalized Silica ◽  
Efficient Catalyst ◽  
Fries Rearrangement ◽  
Free Condition ◽  
Solvent Free Condition ◽  
Work Up

Introduction: We developed a simple, fast and new method for the Fries rearrangement of aryl esters. Materials and Methods: 4-Hydroxy pyridinium triflate functionalized silica is a very efficient, reusable and economically available catalyst for the Fries rearrangement in solvent-free condition and under microwave irradiation. Results and Discussion: Also, a notable selectivity was observed in the presence of 4-hydroxy pyridinium triflate functionalized silica. Conclusion: Selectivity, shorter reaction time, high yield, and easy work-up are advantages of this synthetic method.

Diastereoselective Reduction of Selected α-substituted β-keto Esters and the Assignment of the Relative Configuration by 1H-NMR Spectroscopy

2020 ◽  
Vol 07 ◽  
Author(s):  
Christian Trapp ◽  
Corinna Schuster ◽  
Chris Drewniok ◽  
Dieter Greif ◽  
Martin Hofrichter
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Selective Reduction ◽  
Reducing Agents ◽  
Relative Configuration ◽  
Curtius Rearrangement ◽  
Keto Esters ◽  
Hydroxy Esters ◽  
Diastereoselective Reduction

Background:: Chiral β-hydroxy esters and α-substituted β-hydroxy esters represent versatile building blocks for pheromones, β-lactam antibiotics and 1,2- or 1,3-aminoalcohols. Objective:: Synthesis of versatile α-substituted β-keto esters and their diastereoselective reduction to the corresponding syn- or anti-α-substituted β-hydroxy esters. Assignment of the relative configuration by NMR-spectroscopy after a CURTIUS rearrangement of α-substituted β-keto esters to 4-substituted 5-methyloxazolidin-2-ones. Method:: Diastereoselective reduction was achieved by using different LEWIS acids (zinc, titanium and cerium) in combination with complex borohydrides as reducing agents. Assignment of the relative configuration was verified by 1H-NMR spectroscopy after CURTIUS-rearrangement of α-substituted β-hydroxy esters to 4-substituted 5-methyloxazolidin-2-ones. Results:: For the syn-selective reduction, titanium tetrachloride (TiCl4) in combination with a pyridine-borane complex (py BH3) led to diastereoselectivities up to 99% dr. High anti-selective reduction was achieved by using cerium trichloride (CeCl3) and steric hindered reducing agents such as lithium triethylborohydride (LiEt3BH). After CURTIUS-rearrangement of each α-substituted β-hydroxy ester to the corresponding 4-substituted 5-methyloxazolidin-2-one, the relative configuration was confirmed by 1H NMR-spectroscopy. Conclusion:: We have expanded the procedure of LEWIS acid-mediated diastereoselective reduction to bulky α-substituents such as the isopropyl group and the electron withdrawing phenyl ring.

Facile synthesis of organosilica-capped mesoporous silica nanocarriers with selective redox-triggered drug release properties for safe tumor chemotherapy

2019 ◽  
Vol 7 (5) ◽  
pp. 1825-1832 ◽  
Author(s):  
Luying Shen ◽  
Shan Pan ◽  
Dechao Niu ◽  
Jianping He ◽  
Xiaobo Jia ◽  
...  
Keyword(s):  
Drug Release ◽  
Mesoporous Silica ◽  
Facile Synthesis ◽  
Triggered Drug Release ◽  
Facile Route

We develop a facile route to synthesize organosilica-capped mesoporous silica nanocarriers for efficient and safe redox-triggered tumor chemotherapy.

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