Magnesium Complexes Containing η1- and η3-Pyrrolyl or Ketiminato Ligands: Synthesis, Structural Investigation and ϵ-Caprolactone Ring-Opening Polymerisation

2011 ◽  
Vol 2011 (36) ◽  
pp. 5530-5537 ◽  
Author(s):  
Li-Feng Hsueh ◽  
Nien-Tsu Chuang ◽  
Cheng-Yuan Lee ◽  
Amitabha Datta ◽  
Jui-Hsien Huang ◽  
...  
Keyword(s):  
Ring Opening ◽  
Structural Investigation ◽  
Magnesium Complexes

Structural Investigation of a Configurationally Stable Seven-Membered Bridged Biaryl of Relevance for Atroposelective Biaryl Syntheses*

2003 ◽  
Vol 58 (2-3) ◽  
pp. 231-236 ◽  
Author(s):  
Gerhard Bringmann ◽  
Robert-Michael Pfeifer ◽  
Christian Rummey ◽  
Thomas Pabst ◽  
Dirk Leusser ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Ring Opening ◽  
Structural Investigation ◽  
X Ray Diffraction ◽  
Cleavage Reaction ◽  
Perfect Agreement ◽  
X Ray ◽  
Ether Bridge ◽  
Axially Chiral ◽  
Aromatic Systems

The atroposelective ring opening of lactone-bridged biaryl systems is the key step in the total synthesis of a series of axially chiral biaryl natural products and useful reagents or catalysts for asymmetric synthesis. For a more in-depth understanding of the mechanism and stereochemical course of this remarkable cleavage reaction, a seven-membered ether analog of such useful biaryl lactones has been investigated structurally, both experimentally, by X-ray diffraction analysis, and by ab initio calculations (B3LYP/6-31G*). In a nearly perfect agreement, both methods show that these seven-membered bridged biaryls do not constitute helicene-like distorted molecules, but ‘true’ biaryls, whose sufficiently long lactone or ether bridge allows the two aromatic systems to adopt a large dihedral angle to each other, without any noticeable deviation from planarity for the two aromatic systems - in contrast to related six-membered analogs, which can rather be considered as helicene-like twisted polycyclic systems.

Diastereoselective synthesis of chiral aminophenolate magnesium complexes and their application in the stereoselective polymerization of rac-lactide and rac-β-butyrolactone

2016 ◽  
Vol 45 (27) ◽  
pp. 10942-10953 ◽  
Author(s):  
Haobing Wang ◽  
Jianshuang Guo ◽  
Yang Yang ◽  
Haiyan Ma
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Diastereoselective Synthesis ◽  
Magnesium Complexes

A series of magnesium silylamido complexes supported by chiral aminophenolate ligands were synthesized, and their catalytic behaviors toward the ring-opening polymerization of rac-lactide (LA) and rac-β-butyrolactone (BBL) were explored.

scholarly journals Synthesis, biophysical properties, and RNase H activity of 6’-difluoro[4.3.0]bicyclo-DNA

2019 ◽  
Vol 15 ◽  
pp. 79-88 ◽  
Author(s):  
Sibylle Frei ◽  
Adam K Katolik ◽  
Christian J Leumann
Keyword(s):  
Building Block ◽  
Ring Opening ◽  
Structural Investigation ◽  
Cyclopropane Ring ◽  
Cd Spectroscopy ◽  
Rnase H ◽  
Biophysical Properties ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cleavage Assay

Here we present the synthesis, the biophysical properties, and the RNase H profile of 6’-difluorinated [4.3.0]bicyclo-DNA (6’-diF-bc4,3-DNA). The difluorinated thymidine phosphoramidite building block was synthesized starting from an already known gem-difluorinated tricyclic glycal. This tricyclic siloxydifluorocyclopropane was converted into the [4.3.0]bicyclic nucleoside via cyclopropane ring-opening through the addition of an electrophilic iodine during the nucleosidation step followed by reduction. The gem-difluorinated bicyclic nucleoside was then converted into the corresponding phosphoramidite building block which was incorporated into oligonucleotides. Thermal denaturation experiments of these oligonucleotides hybridized to complementary DNA or RNA disclosed a significant destabilization of both duplex types (ΔT m/mod = −1.6 to −5.5 °C). However, in the DNA/RNA hybrid the amount of destabilization could be reduced by multiple insertions of the modified unit. In addition, CD spectroscopy of the oligonucleotides hybridized to RNA showed a similar structure than the natural DNA/RNA duplex. Furthermore, since the structural investigation on the nucleoside level by X-ray crystallography and ab initio calculations pointed to a furanose conformation in the southern region, a RNase H cleavage assay was conducted. This experiment revealed that the oligonucleotide containing five modified units was able to elicit the RNase H-mediated cleavage of the complementary RNA strand.

Magnesium complexes containing bis-amido-oxazolinate ligands as efficient catalysts for ring opening polymerisation of l-lactide

2009 ◽  
pp. 9068 ◽  
Author(s):  
Ming-Tsz Chen ◽  
Ping-Jung Chang ◽  
Chi-An Huang ◽  
Kuo-Fu Peng ◽  
Chi-Tien Chen
Keyword(s):  
Ring Opening ◽  
Magnesium Complexes

(Benz)Imidazolin-2-iminato Aluminum, Zinc, and Magnesium Complexes and Their Applications in Ring Opening Polymerization of ε-Caprolactone

2019 ◽  
Vol 58 (19) ◽  
pp. 13426-13439 ◽  
Author(s):  
Heng Liu ◽  
Maxim Khononov ◽  
Natalia Fridman ◽  
Matthias Tamm ◽  
Moris S. Eisen
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Magnesium Complexes

Discrete Cationic Zinc and Magnesium Complexes for Dual Organic/Organometallic-Catalyzed Ring-Opening Polymerization of Trimethylene Carbonate

2012 ◽  
Vol 18 (30) ◽  
pp. 9360-9370 ◽  
Author(s):  
Pierre Brignou ◽  
Sophie M. Guillaume ◽  
Thierry Roisnel ◽  
Didier Bourissou ◽  
Jean-François Carpentier
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Trimethylene Carbonate ◽  
Magnesium Complexes

Ring-opening polymerization of lactides catalyzed by magnesium complexes coordinated with NNO-tridentate pyrazolonate ligands

2012 ◽  
Vol 51 (3) ◽  
pp. 696-707 ◽  
Author(s):  
Hui-Ju Chuang ◽  
Hsiao-Li Chen ◽  
Jian-Li Ye ◽  
Zn-Yun Chen ◽  
Pei-Ling Huang ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Magnesium Complexes
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