A Rapid, High-Yield Method for 5′-Hydroxyl Protection in Very Reactive and Amino Group Modified Nucleosides Using Dimethoxytrityl Tetrafluoroborate

1996 ◽  
Vol 15 (5) ◽  
pp. 1029-1039 ◽  
Author(s):  
Mahesh K. Lakshman ◽  
Barbara Zajc
Keyword(s):  
Modified Nucleosides ◽  
High Yield ◽  
Amino Group

scholarly journals Stereoselective synthesis of 2′-modified nucleosides by using ortho-alkynyl benzoate as a gold(i)-catalyzed removable neighboring participation group

RSC Advances ◽  
2017 ◽  
Vol 7 (4) ◽  
pp. 1814-1817 ◽  
Author(s):  
Haixin Ding ◽  
Chuang Li ◽  
Yirong Zhou ◽  
Sanguo Hong ◽  
Ning Zhang ◽  
...  
Keyword(s):  
Stereoselective Synthesis ◽  
Modified Nucleosides ◽  
High Yield

ortho-Alkynyl benzoate was developed as a neighboring participation group in stereoselective synthesis of nucleosides, which could be removed using gold(i)-catalysis to afford 2′-OH nucleosides in high yield and selectivity.

Dihydrotestosterone with an Ammonium Centre in the Position 16β

1997 ◽  
Vol 62 (4) ◽  
pp. 656-664 ◽  
Author(s):  
Barbora Slavíková ◽  
Alexander Kasal ◽  
Miloš Buděšínský
Keyword(s):  
Quaternary Ammonium ◽  
Water Soluble ◽  
High Yield ◽  
Partial Hydrolysis ◽  
Amino Group ◽  
Alternative Synthesis ◽  
Group Participation ◽  
Neighbouring Group Participation ◽  
Hydrolysis Of

In an alternative synthesis of 17β-hydroxy-16β-(piperidin-1-yl)-5α-androstan-3-one (4), neighbouring group participation between a 17β-carbonyloxy group and the 16β-amino group was used and a high yield partial hydrolysis of 3β,17β-diacetoxy-16β-(piperidin-1-yl)-5α-androstane (11) was developed. Interference of the neighbouring group participation was also apparent in another 17β-acetoxy derivative - in oxidation of compound 12 to 13. Compound 4 was converted into water-soluble derivatives, i.e. quaternary ammonium derivatives 17 to 20.

Synthesis of Water Soluble Undecagold Clusters for Specific Labelling of Proteins

1989 ◽  
Vol 44 (10) ◽  
pp. 1313-1322 ◽  
Author(s):  
Werner Jahn
Keyword(s):  
Free Amino ◽  
Heavy Atom ◽  
Acetyl Derivative ◽  
Water Soluble ◽  
High Yield ◽  
Amino Group ◽  
Specific Labelling

A highly water soluble undecagold cluster was prepared using a N-hydroxyethyl-N-acetyl-derivative of 4,4′,4″-phosphinidynetri(benzenemethanamine). Monofunctional clusters were synthesized in high yield by the exchange of ligands with phosphines having one free amino group. The clusters can be used for heavy atom labelling of proteins after introduction of a reactive maleimido group.

Quality films from carbon fiber evaporation for thorough coverage of TEM grids

1988 ◽  
Vol 46 ◽  
pp. 418-419
Author(s):  
N. Tempel ◽  
M. C. Ledbetter
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Carbon Films ◽  
Low Noise ◽  
Vacuum Evaporation ◽  
High Yield ◽  
Good Adhesion ◽  
Noise Structure ◽  
Resolution Electron ◽  
Carbon Foils

Carbon films have been a support of choice for high resolution electron microscopy since the introduction of vacuum evaporation of carbon. The desirable qualities of carbon films and methods of producing them has been extensively reviewed. It is difficult to get a high yield of grids by many of these methods, especially if virtually all of the windows must be covered with a tightly bonded, quality film of predictable thickness. We report here a method for producing carbon foils designed to maximize these attributes: 1) coverage of virtually all grid windows, 2) freedom from holes, wrinkles or folds, 3) good adhesion between film and grid, 4) uniformity of film and low noise structure, 5) predictability of film thickness, and 6) reproducibility.Our method utilizes vacuum evaporation of carbon from a fiber onto celloidin film and grid bars, adhesion of the film complex to the grid by carbon-carbon contact, and removal of the celloidin by acetone dissolution. Materials must be of high purity, and cleanliness must be rigorously maintained.

Effects of high pressure on the crystallization of carbon fiber reinforced polyetheretherketone (CF/PEEK) laminate composites

1990 ◽  
Vol 48 (4) ◽  
pp. 876-877
Author(s):  
Hong-Ming Lin ◽  
C. H. Liu ◽  
R. F. Lee
Keyword(s):  
High Pressure ◽  
Carbon Fiber ◽  
Sample Surface ◽  
High Yield ◽  
Fiber Reinforced ◽  
Laminate Composites ◽  
Peek Composite ◽  
Continuous Carbon Fiber ◽  
Carbon Fiber Reinforced

Polyetheretherketone (PEEK) is a crystallizable thermoplastic used as composite matrix materials in application which requires high yield stress, high toughness, long term high temperature service, and resistance to solvent and radiation. There have been several reports on the crystallization behavior of neat PEEK and of CF/PEEK composite. Other reports discussed the effects of crystallization on the mechanical properties of PEEK and CF/PEEK composites. However, these reports were all concerned with the crystallization or melting processes at or close to atmospheric pressure. Thus, the effects of high pressure on the crystallization of CF/PEEK will be examined in this study.The continuous carbon fiber reinforced PEEK (CF/PEEK) laminate composite with 68 wt.% of fibers was obtained from Imperial Chemical Industry (ICI). For the high pressure experiments, HIP was used to keep these samples under 1000, 1500 or 2000 atm. Then the samples were slowly cooled from 420 °C to 60 °C in the cooling rate about 1 - 2 degree per minute to induce high pressure crystallization. After the high pressure treatment, the samples were scanned in regular DSC to study the crystallinity and the melting temperature. Following the regular polishing, etching, and gold coating of the sample surface, the scanning electron microscope (SEM) was used to image the microstructure of the crystals. Also the samples about 25mmx5mmx3mm were prepared for the 3-point bending tests.

Catalytic enantioselective synthesis of indolizino[8,7-b]indole alkaloid derivatives based on the tandem reaction of tertiary enamides

2021 ◽  
Author(s):  
Xin-Ming Xu ◽  
Ming Xie ◽  
Jiazhu Li ◽  
Mei-Xiang Wang
Keyword(s):  
Indole Alkaloid ◽  
Enantioselective Synthesis ◽  
High Yield ◽  
Tandem Reaction ◽  
Indole Derivatives

An exquisite Pybox/Cu(OTf)2-catalyzed asymmetric tandem reaction of tertiary enamides was developed, which enabled the expeditious synthesis of indolizino[8,7-b]indole derivatives in high yield, excellent enantioselectivity and diastereoselectivity.

Sign in / Sign up

Export Citation Format

Share Document