Search results for "Alkylation"
showing 10 items of 219 documents
Improved automated synthesis of [18F]fluoroethylcholine as a radiotracer for cancer imaging.
2007
[(18)F]Fluoroethylcholine has been recently introduced as a promising (18)F-labelled analogue of [(11)C]choline which had been previously described as a tracer for metabolic cancer imaging with positron emission tomography (PET). Due to the practical advantages of using the longer-lived radioisotope (18)F (t(1/2)=110 min), offering the opportunity of a more widespread clinical application, we established a reliable, fully automated synthesis for its production using a modified, commercially available module. [(18)F]Fluoroethylcholine was prepared from N,N-dimethylaminoethanol by iodide catalyzed alkylation with 1-[(18)F]fluoro-2-tosylethane as alkylating agent, resulting in a total radioche…
Selective binding to monoamine oxidase A: in vitro and in vivo evaluation of (18)F-labeled β-carboline derivatives.
2015
In this study we synthesized four different (18)F-labeling precursors for the visualization of the monoamino oxidase A using harmol derivatives. Whereas two are for prosthetic group labeling using [(18)F]fluoro-d2-methyl tosylate and 2-[(18)F]fluoroethyl-tosylate, the other three precursors are for direct nucleophilic (18)F-labeling. Additionally the corresponding reference compounds were synthesized. The syntheses of [(18)F]fluoro-d2-methyl-harmol and 2-[(18)F]fluoroethyl-harmol were carried out using harmol as starting material. For direct nucleophilic (18)F-labeling of the tracers carrying oligoethyled spacers (PEG), a toluenesulfonyl leaving group was employed. The radiolabeling, purifi…
1988
Synthese par alkylation reductrice de l'anthracene par des electrophiles bifonctionnels comme le dibromo-1,3 propane. Le polymere du titre est un precurseur du polymere redox polyanthrylenetrimethylene
Hydroformylation of 1-Octene in Supercritical Carbon Dioxide: Can Alkylation of Arylphosphines with tertButyl Groups Lead to Soluble and Active Catal…
2008
Abstract The possibility of increasing the solubility and activity of rhodium catalysts in the hydroformylation of 1-octene in supercritical carbon dioxide (scCO2) by attachment of tertbutyl (tBu) groups to the triarylphosphine ligand was investigated. The solubility of the parent and monoalkylated ligands in a mixture of gaseous components (CO2/CO/H2) was evaluated by visual observation in a view cell. In the case of triphenylphosphine, introduction of one tertbutyl group does not seem to affect the solubility of the phosphine. When the behaviour of (diphenyl)biphenylphosphine and (para-tertbutyldiphenyl)biphenylphosphine was compared a clear solubilising effect of the tBu group was observ…
New Approach to 1,4-Benzoxazin-3-ones by Electrochemical C-H Amination.
2017
1,4-Benzoxazin-3-ones are important structural motifs in natural products and bioactive compounds. Usually the synthesis of benzoxazinones requires transition metal catalysts and pre-functionalized substrates, e.g. aryl halides. However, the anodic C,H amination of phenoxy acetates offers a very efficient and sustainable access to these heterocycles. The herein presented electrochemical protocol can be applied to a broad scope of alkylated substrates. Even tert-butyl moieties or halogen substituents are compatible with this versatile method.
Electrochemical Amination of Less-Activated Alkylated Arenes Using Boron-Doped Diamond Anodes
2016
The anodic C–H amination of aromatic compounds is a powerful and versatile method for the synthesis of aniline derivatives. By using boron-doped diamond (BDD) anodes, a method initially described by Yoshida et al. for electron-rich arenes was expanded to less-activated aromatic systems e.g., simple alkylated benzene derivatives. Anodes based on sp3 carbon seem to be the key for the electrochemical amination reaction. The corresponding primary anilines are obtained in good yields. Despite the cationic intermediates of the electrolytic reaction tert-butyl moieties are tolerated.
Stereoselective Access to Fluorinated and Non-fluorinated Quaternary Piperidines: Synthesis of Pipecolic Acid and Iminosugar Derivatives
2012
The preparation of optically pure quaternary piperidines, both fluorinated and non-fluorinated, has been achieved from a chiral imino lactone derived from (R)-phenylglycinol. In the case of the fluorinated derivatives, the addition of (trifluoromethyl)trimethylsilane (TMSCF(3)) followed by iodoamination and migration of the CF(3) group allowed access to four derivatives of α-(trifluoromethyl)pipecolic acid. A theoretical study of the CF(3)-group rearrangement has been carried out to help establish the reaction mechanism of this uncommon transformation. Moreover, a route to trifluoromethyl-substituted iminosugars was also developed through the diastereoselective dihydroxylation of suitable s…
Interaction of iron(II)-heme and artemisinin with a peptide mimic of Plasmodium falciparum HRP-II
2007
Abstract The interaction of heme or heme-artemisinin adducts (heme-art) with different peptides mimicking repeat sequences of the Histidine-Rich-Protein-II of Plasmodium falciparum (PfHRP-II) was investigated. The pseudo-first order rate constants of the coordination of heme or heme-art onto a histidine rich peptide, used as a mimic of PfHRP-II putative heme binding sequence, are of the same order of magnitude, namely 42 and 14 s −1 , respectively. Despite the intrinsic reactivity of the carbonyl at C10 of heme-art toward a hydroxyl function, a peptide containing a serine or threonine residue does not readily react with heme-art adducts. Therefore, a much higher affinity of heme-art compare…
Dažu ivabradīna sintēzes stadiju pētījumi
2018
Dažu ivabradīna sintēzes stadiju pētīšana. Lugovskojs R., zinātniskie vadītāji MSc. Reine I. un Dr. chem. doc. Kļimenkovs I. Bakalaura darbs, 36 lappuses, 25 attēli, 3 tabulas, 24 literatūras avoti. Latviešu valodā. Darbā ir pētītas triju svarīgo ivabradīna starpproduktu - 7,8-dimetoksi-1H-benzo[d]azepin-2(3H)-ona, 3-(3-hlorpropil)-7,8-dimetoksi-1H-dihidro-2H-3-benzo[d]azepin-2(3H)-ona un dehidroivabradīna iegūšanas metodes ar mērķi atrast optimālus reakcijas apstākļus, kas piemēroti sintēzes veikšanai rūpnieciskā mērogā. Darbā ir apkopota pieejamā literatūra par ivabradīna un tā svarīgāko starpproduktu iegūšanas metodēm. Īpaši ir pētīta 7,8-dimetoksi-1H-benzo[d]azepin-2(3H)-ona alkilēšana,…
Synthesis and biological evaluation of new indazole derivatives
2010
New N-methyl and N-ethyl substitutions in the indazole nucleus are reported by reacting 3-(2-aminobenzamido)indazole and the appropriate trimethyl/triethyl orthobenzoate. Single crystal X-ray analysis confirms the N-ethylation position for the 3-(1-ethyl-1H-indazol-3-yl)-2-phenylquinazolin-4(3H)-one derivative 3f. Compounds 11a-d and 3a-d were tested to evaluate their antimicrobial, their antiproliferative activity and their COX inhibitory activities showing scarce or moderately antiproliferative activity and some inhibitory activity against COX-1 and COX-2.