scholarly journals One tool to bring them all: Au-catalyzed synthesis of B,O- and B,N-doped PAHs from boronic and borinic acids

2021 ◽  
Vol 12 (16) ◽  
pp. 5898-5909
Author(s):  
Omar Ouadoudi ◽  
Tanja Kaehler ◽  
Michael Bolte ◽  
Hans-Wolfram Lerner ◽  
Matthias Wagner
Keyword(s):  
Reaction Step ◽  
Final Reaction

Singly and doubly B,E-doped PAHs were synthesized using a protocol that starts from easy-to-handle boronic and borinic acids and offers the possibility to choose between the preparation of B,O- and B,N-PAHs in the final reaction step.

A New Method for the Preparation of Ifosfamide and Cyclophosphamide

1997 ◽  
Vol 52 (8) ◽  
pp. 943-946 ◽  
Author(s):  
I Neda ◽  
R Sonnenburg ◽  
R Schmutzler ◽  
U Niemeyer ◽  
B Kutscher ◽  
...  
Keyword(s):  
Ammonium Chloride ◽  
Chlorine Atom ◽  
Alkylating Agents ◽  
New Method ◽  
Sulfuryl Chloride ◽  
Reaction Step ◽  
Final Reaction ◽  
Ethyl Amine

The reaction of 2-chloro-3-(2-chloroethyl)-tetrahydro-2H-1,3,2-oxazaphosphorin-2-oxide 1 and 2-chloro-tetrahydro-2H-1,3,2-oxazaphosphorin-2-oxide 2 with 2-(trimethylsilyloxy)ethylamine 3 and bis-[2-(trimethylsiloxy)ethyl]amine 4, respectively, yielded the trimethylsilylated compounds 5 and 6, analogous to ifosfamide and cyclophosphamide. The reaction of 5 and 6 with 2-chloro-1,3,5-trimethyl-1,3,5-triaza-2-phosphorin-4,6-dione 7 led to the diphosphorus compounds 8 and 9 which could be transformed to ifosfamide 11 and cyclophosphamide 12 by treatment with sulfuryl chloride. This synthesis shows that the alkylating agents 2- chloroethylammonium chloride and bis-(2-chloroethyl)ammonium chloride can be avoided and the chlorine atom can be introduced in the final reaction step of the synthesis of 11 and 12.

Processing Immunoperoxidase Labeled Cell Monolayers and Cryostat Sesctions For Electron Microscopy

1985 ◽  
Vol 43 ◽  
pp. 714-715
Author(s):  
K. Chien ◽  
R. Van de Velde ◽  
I.P. Shintaku ◽  
A.F. Sassoon
Keyword(s):  
Cell Monolayer ◽  
Cell Types ◽  
Surface Antigens ◽  
Immunoperoxidase Method ◽  
Reaction Step ◽  
Hot Plate ◽  
Air Drying ◽  
New Approach ◽  
Cell Monolayers ◽  
Glass Slides

Immunoelectron microscopy of neoplastic lymphoma cells is valuable for precise localization of surface antigens and identification of cell types. We have developed a new approach in which the immunohistochemical staining can be evaluated prior to embedding for EM and desired area subsequently selected for ultrathin sectioning.A freshly prepared lymphoma cell suspension is spun onto polylysine hydrobromide- coated glass slides by cytocentrifugation and immediately fixed without air drying in polylysine paraformaldehyde (PLP) fixative. After rinsing in PBS, slides are stained by a 3-step immunoperoxidase method. Cell monolayer is then fixed in buffered 3% glutaraldehyde prior to DAB reaction. After the DAB reaction step, wet monolayers can be examined under LM for presence of brown reaction product and selected monolayers then processed by routine methods for EM and embedded with the Chien Re-embedding Mold. After the polymerization, the epoxy blocks are easily separated from the glass slides by heatingon a 100°C hot plate for 20 seconds.

Oxygenation of 18-hydroxycorticosterone as the final reaction for aldosterone biosynthesis

1984 ◽  
Vol 107 (3) ◽  
pp. 395-400 ◽  
Author(s):  
Itaru Kojima ◽  
Etsuro Ogata ◽  
Hiroshi Inano ◽  
Bun-ichi Tamaoki
Keyword(s):  
Carbon Monoxide ◽  
Hydroxysteroid Dehydrogenase ◽  
Dependent Manner ◽  
In Vitro Production ◽  
Mitochondrial Preparation ◽  
Final Reaction ◽  
Vitro Production ◽  
Dose Dependent ◽  
Cytochrome P 450

Abstract. Incubation of 18-hydroxycorticosterone with the sonicated mitochondrial preparation of bovine adrenal glomerulosa tissue leads to the production of aldosterone, as measured by radioimmunoassay. The in vitro production of aldosterone from 18-hydroxycorticosterone requires both molecular oxygen and NADPH, and is inhibited by carbon monoxide. Cytochrome P-450 inhibitors such as metyrapone, SU 8000. SU 10603, SKF 525A, amphenone B and spironolactone decrease the biosynthesis of aldosterone from 18-hydroxycorticosterone. These results support the conclusion that the final reaction in aldosterone synthesis from 18-hydroxycorticosterone is catalyzed by an oxygenase, but not by 18-hydroxysteroid dehydrogenase. By the same preparation, the production of [3H]aldosterone but not [3H]18-hydroxycorticosterone from [1,2-3H ]corticosterone is decreased in a dose-dependent manner by addition of non-radioactive 18-hydroxycorticosterone.

scholarly journals Bile-pigment formation from different leghaemoglobins. Methine-bridge specificity of coupled oxidation

1978 ◽  
Vol 176 (2) ◽  
pp. 359-364 ◽  
Author(s):  
Päivi Lehtovaara ◽  
Ulla Perttilä
Keyword(s):  
Amino Acid ◽  
Polypeptide Chain ◽  
Broad Bean ◽  
Amino Acid Sequences ◽  
Second Step ◽  
Bile Pigment ◽  
Site Specificity ◽  
Amino Acid Residues ◽  
Reaction Step ◽  
Pigment Formation

The coupled oxidation of leghaemoglobins with O2 and ascorbate yielded oxyleghaemoglobin in the first reaction step, and the second step was the degradation of haem characterized by an A675 increase. Leghaemoglobins were degraded to biliverdin isomers specifically, depending on the structure of the protein. The main leghaemoglobin components of Glycine (soya bean) and Phaseolus (kidney bean) were degraded to biliverdin mixtures containing about 50% of the β-form, about 30% of the α-form and about 20% of the δ-isomer, whereas the leghaemoglobin I components of Vicia (broad bean) and Pisum (pea) were degraded almost exclusively to the β-isomer, with traces of the α-isomer. The amino acid sequences of Glycine and Phaseolus leghaemoglobins resemble each other, as do those of Vicia and Pisum. The site specificity of bile-pigment formation from leghaemoglobins can be tentatively explained by specific differences in the amino acid sequences at those regions of the polypeptide chain that are in the vicinity of the appropriate methine bridges. The ligand-binding site in different leghaemoglobins may be outlined on the basis of the present results, supposing that the haem is degraded when a reduction product of haem-bound O2 reacts with a methine bridge of the haem, and that the bridge specificity is regulated by hindering amino acid residues that determine the location of the bound O2. The residue phenylalanine-CD1 appears to be further away from the haem plane or in a markedly more flexible position in leghaemoglobins than in mammalian globins. The haem-bound oxygen atom B, in Fe–O(A)–O(B), seems to be free to rotate in all directions except that of the γ-bridge in Glycine and Phaseolus leghaemoglobins, but its position in Vicia and Pisum leghaemoglobin I might be restricted to the direction of the β-methine bridge.

scholarly journals An alternative method for Staphylococcus aureus DNA isolation

2008 ◽  
Vol 60 (2) ◽  
pp. 299-306 ◽  
Author(s):  
L. Chapaval ◽  
D.H. Moon ◽  
J.E. Gomes ◽  
F.R. Duarte ◽  
S.M. Tsai
Keyword(s):  
Staphylococcus Aureus ◽  
Genomic Dna ◽  
Dna Isolation ◽  
Environmental Isolates ◽  
Reaction Volume ◽  
High Quality ◽  
Rapid Procedure ◽  
Final Reaction ◽  
Staphylococcal Enterotoxins ◽  
Final Reaction Volume

This study describes a rapid procedure for the isolation of genomic DNA from Staphylococcus aureus that yielded a good amount of high quality DNA for the amplification of staphylococcal enterotoxins genes (A, B, C, D, and E) and the TSST-1 gene as well as enzymatic restriction (HaeIII) from environmental isolates. With this method, it was possible to detect these genes in a sample containing as little as 10(5) cells with positive PCR reactions obtained from approximately 10pg of DNA in a final reaction volume of 25µl.

scholarly journals Nanoribbons with Non-Alternant Topology from Fusion of Polyazulene: Carbon Allotropes Beyond Graphene

2019 ◽  
Author(s):  
Qitang Fan ◽  
Daniel Martin-Jimenez ◽  
Daniel Ebeling ◽  
Claudio K. Krug ◽  
Lea Brechmann ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Low Temperature ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Scanning Probe ◽  
Two Dimensional ◽  
Reaction Step ◽  
Functional Theory ◽  
Carbon Allotropes ◽  
Temperature Scanning

Various two-dimensional (2D) carbon allotropes with non-alternant topologies, such as pentaheptites and phagraphene, have been proposed. Predictions indicate that these metastable carbon polymorphs, which contain odd-numbered rings, possess unusual (opto)electronic properties. However, none of these materials has been achieved experimentally due to synthetic challenges. In this work, by using on-surface synthesis, nanoribbons of the non-alternant graphene allotropes, phagraphene and tetra-penta-hepta(TPH)-graphene have been obtained by dehydrogenative C-C coupling of 2,6-polyazulene chains. These chains were formed in a preceding reaction step via on-surface Ullmann coupling of 2,6-dibromoazulene. Low-temperature scanning probe microscopies with CO-functionalized tip and density functional theory calculations have been used to elucidate their structural properties. <br>

DENSITY FUNCTIONAL STUDY OF SELECTED MONO-ZINC AND GEM-DIZINC RADICAL CARBENOID CYCLOPROPANATION REACTIONS: OBSERVATION OF AN EFFICIENT RADICAL ZINC CARBENOID CYCLOPROPANATION REACTION AND THE INFLUENCE OF THE LEAVING GROUP ON RING CLOSURE

2003 ◽  
Vol 02 (03) ◽  
pp. 357-369 ◽  
Author(s):  
CUNYUAN ZHAO ◽  
DONG-QI WANG ◽  
DAVID LEE PHILLIPS
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Radical Reaction ◽  
Ring Closure ◽  
Functional Study ◽  
Reaction Step ◽  
Leaving Group ◽  
Reaction Barriers ◽  
Leaving Groups ◽  
Zinc Carbenoid

We report a theoretical study of the cyclopropanation reactions of EtZnCHI, (EtZn)2CH EtZnCHZnI, and EtZnCIZnI radicals with ethylene. The mono-zinc and gem-dizinc radical carbenoids can undergo cyclopropanation reactions with ethylene via a two-step reaction mechanism similar to that previously reported for the CH2I and IZnCH2 radicals. The barrier for the second reaction step (ring closure) was found to be highly dependent on the leaving group of the cyclopropanation reaction. In some cases, the (di)zinc carbenoid radical undergoes cyclopropanation via a low barrier of about 5–7 kcal/mol on the second reaction step and this is lower than the CH2I radical reaction which has a barrier of about 13.5 kcal/mol for the second reaction step. Our results suggest that in some cases, zinc radical carbenoid species have cyclopropanation reaction barriers that can be competitive with their related molecular Simmons-Smith carbenoid species reactions and produce somewhat different cyclopropanated products and leaving groups.

Sign in / Sign up

Export Citation Format

Share Document