Preparation of (Z)-1,2-dichloroalkenes from terminal alkynes

2012 ◽  
Vol 90 (7) ◽  
pp. 625-630 ◽  
Author(s):  
Ningzhang Zhou ◽  
Qiang Wang ◽  
Alan J. Lough ◽  
Hongbin Yan
Keyword(s):  
Terminal Alkynes ◽  
Mucochloric Acid ◽  
Potassium Hydrogen

(Z)-1,2-Dihaloalkenes are thermodynamically disfavoured of the two stereoisomers. This paper reports the synthesis of some (Z)-1,2-dichloroalkene analogues from mucochloric acid. A more versatile approach involved the chloroboration of terminal alkynes to yield corresponding (Z)-chloroboronic acid as a first step. Treatment of the organoboronic acid with potassium hydrogen difluoride followed by tetrabutylammonium trichloride gave (Z)-1,2-dichloroalkenes in moderate to good yields in a stereospecific manner.

Comparison of two asynchronous QCT methods

2020 ◽  
Vol 24 (4) ◽  
pp. 108-118
Author(s):  
A. V. Petraikin ◽  
A. K. Smorchkova ◽  
N. D. Kudryavtsev ◽  
K. A. Sergunova ◽  
Z. R. Artyukova ◽  
...  
Keyword(s):  
Bone Densitometry ◽  
Pearson Correlation ◽  
Calibration Data ◽  
Mineral Density ◽  
Quantitative Ct ◽  
Short Period ◽  
Potassium Hydrogen ◽  
Patients At Risk ◽  
Ray Density ◽  
The Difference

Rationale. Quantitative CT (QCT) bone densitometry with asynchronous calibration not require a phantom during the scan procedure. Based on calibration data it converts X-ray density in HU to bone mineral density (BMD). Given the large number of CT studies performed on patients at risk of osteoporosis, there is a need for a hands-on method capable of assessing BMD in a short period of time without tailored software or protocols.Goal. To develop a method for QCT bone densitometry using an PHK (PHantom Kalium), to compare the volume BMD measurements with the QCT data with asynchronous calibration provided by software from a reputable developer.Methods. The studies were performed at 64-slice CT unit with body scanning parameters. The BMD was measured using two techniques: 1) QCT with asynchronous calibration using software from a reputable developer; 2) QCT using a PHK phantom (QCT-PHK). For convert the HU to BMD values, we scanned the PHK phantom and calculate correction factor. Phantom contains “vertebrae” filled with potassium hydrogen phosphate in different concentrations. In both methods, the BMD values measured for LI–II, and sometimes for ThXII, LIII.Results. The study enrolled 65 subjects (11 male and 54 female patients); median age 69.0 years. A comparison of the vertebrae BMD measured by QCT and QCT-PHK revealed a significant linear Pearson correlation r = 0.977 (p < 0.05). The Bland–Altman analysis demonstrated a lack of relationship between the difference in measurements and the average BMD and a systematic BMD; bias of +4.50 mg/ml in QCT vs. QCT-PHK. Differences in the division into groups osteoporosis / osteopenia / norm according to the ACR criteria for the two methods were not significant.Conclusion. The developed asynchronous QCT-PHK method measure BMD comparable to the widely used QCT with asynchronous calibration. This method can be used for opportunistic screening for osteoporosis.

Synthesis of Novel 1,2,3-Triazole Derivatives of Isocoumarins and 3,4-Dihydroisocoumarin with Potential Antiplasmodial Activity In Vitro

2020 ◽  
Vol 16 ◽  
Author(s):  
Lucas da Silva Santos ◽  
Matheus Fillipe Langanke de Carvalho ◽  
Ana Claudia de Souza Pinto ◽  
Amanda Luisa da Fonseca ◽  
Julio César Dias Lopes ◽  
...  
Keyword(s):  
Triazole Ring ◽  
Antiplasmodial Activity ◽  
World Health ◽  
Dipolar Cycloaddition ◽  
Terminal Alkynes ◽  
The World ◽  
Ic50 Values ◽  
Derivatives Of ◽  
Active Substances

Background: Malaria greatly affects the world health, having caused more than 228 million cases only in 2018. The emergence of drug resistance is one of the main problems in its treatment, demonstrating the urge for the development of new antimalarial drugs. Objective: Synthesis and in vitro antiplasmodial evaluation of triazole compounds derived from isocoumarins and a 3,4- dihydroisocoumarin. Method: The compounds were synthesized in 4 to 6-step reactions with the formation of the triazole ring via the Copper(I)-catalyzed 1,3-dipolar cycloaddition between isocoumarin or 3,4-dihydroisocoumarin azides and terminal alkynes. This key reaction provided compounds with an unprecedented connection of isocoumarin or 3,4-dihydroisocoumarin and the 1,2,3-triazole ring. The products were tested for their antiplasmodial activity against a Plasmodium falciparum chloroquine resistant and sensitive strains (W2 and 3D7, respectively). Results: Thirty-one substances were efficiently obtained by the proposed routes with an overall yield of 25-53%. The active substances in the antiplasmodial test displayed IC50 values ranging from 0.68-2.89 μM and 0.85-2.07 μM against W2 and 3D7 strains, respectively.

Two-dimensional metallic hydrogen in the potassium-hydrogen-graphite ternary intercalation compound

1990 ◽  
Vol 64 (3) ◽  
pp. 319-322 ◽  
Author(s):  
Seiichi Miyajima ◽  
Masashi Kabasawa ◽  
Takehiko Chiba ◽  
Toshiaki Enoki ◽  
Yusei Maruyama ◽  
...  
Keyword(s):  
Intercalation Compound ◽  
Two Dimensional ◽  
Metallic Hydrogen ◽  
Potassium Hydrogen

On-Surface Synthesis of Carbon-Based Scaffolds and Nanomaterials Using Terminal Alkynes

2015 ◽  
Vol 48 (7) ◽  
pp. 2140-2150 ◽  
Author(s):  
Florian Klappenberger ◽  
Yi-Qi Zhang ◽  
Jonas Björk ◽  
Svetlana Klyatskaya ◽  
Mario Ruben ◽  
...  
Keyword(s):  
Terminal Alkynes ◽  
Carbon Based

Importance of bases on the copper-catalyzed oxidative homocoupling of terminal alkynes to 1,4-disubstituted 1,3-diynes

2012 ◽  
Vol 53 (41) ◽  
pp. 5559-5561 ◽  
Author(s):  
Xinjiang Niu ◽  
Chunju Li ◽  
Jian Li ◽  
Xueshun Jia
Keyword(s):  
Terminal Alkynes ◽  
Oxidative Homocoupling

Dimethylzinc-mediated enantioselective addition of terminal alkynes to 1,2-diketones using perhydro-1,3-benzoxazines as ligands

2021 ◽  
Author(s):  
Elena Prieto ◽  
Rebeca Infante ◽  
Javier Nieto ◽  
Celia Andres
Keyword(s):  
Chiral Ligand ◽  
Terminal Alkynes ◽  
Conformationally Restricted ◽  
Enantioselective Addition

A conformationally restricted perhydro-1,3-benzoxazine derived from (-)-8-aminomenthol behaves as a good chiral ligand in the dimethylzinc-mediated enantioselective monoaddition of aromatic and aliphatic terminal alkynes to 1,2-diketones. The corresponding α-hydroxyketones were...

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