Search results for "ACYLATION"
showing 10 items of 87 documents
Alkoxy-, Acyloxy-, and Bromomethylation of Resorcinarenes
2004
Reaction of resorcinarene octols with tris-hydroxymethylmethylamine (TRIS), formaldehyde, and alcohols results in tetraalkoxymethylation of the resorcinol rings. Harsh acylation of aminomethylated resorcinarenes with acid anhydrides leads to the complete acylation of eight hydroxyls and substitution of the amino versus acyloxy groups. Acyloxymethylated resorcinarene 6b can be transformed into a tetrabromomethylated derivative 7 through the reaction with HBr in acetic acid.
ChemInform Abstract: Solution versus Fluorous versus Solid-Phase Synthesis of 2,5-Disubstituted 1,3-Azoles. Preliminary Antibacterial Activity Studie…
2010
A small library of compounds with an oxa(thia)zole scaffold and structural diversity in both positions 2 and 5 has been synthesized. Double acylation of a protected glycine affords intermediate alpha-amido-beta-ketoesters, which in turn can be dehydrated to afford 1,3-oxazoles or reacted with Lawesson's reagent to furnish 1,3-thiazoles. This procedure was designed with its adaptation to fluorous techniques in mind. Thus, when a protected glycine with a fluorous tag in the ester moiety is used as a starting material, the synthesis can be easily completed without column chromatography purification of intermediate compounds with good to excellent yields, thus affording a suitable entry to the …
Ethyl Pyrogallarene and Pyrogallarene: Synthesis, Structural Analysis and Derivatization
2004
In the acid-catalyzed synthesis of ethyl pyrogall[4]arene, a novel hexamer, ethyl pyrogall[6] arene, is obtained as a readily isolable minor product. Pyrogall[6]arene can be isolated from the reaction mixture in three different ways yielding the hexamer in different forms and stabilities. Crystallization from DMSO and then recrystallization from acetone gives a stable crystalline solid, recrystallization directly from acetone yields an unstable white powder, while direct recrystallization from THF gives a stable white powder. Both pyrogall[4]arene and pyrogall[6]arene crystallize readily with DMSO filling the voids in the crystal lattice. Co-crystallization studies of the hexamer isolated b…
Multicatalytic Transformation of (Meth)acrylic Acids: a One-Pot Approach to Biobased Poly(meth)acrylates
2021
International audience; Shifting from petrochemical feedstocks to renewable resources can address some of the environmental issues associated with petrochemical extraction and make plastics production sustainable. Therefore, there is a growing interest in selective methods for transforming abundant renewable feedstocks into monomers suitable for polymer production. Reported herein are one-pot catalytic systems, that are active,<br>productive, and selective under mild conditions for the synthesis of copolymers from renewable materials. Each system allows for anhydride formation, alcohol acylation and/or acid esterification, as well as polymerization of the formed (meth)- acrylates, providi…
Breakthrough in the α-Perchlorination of Acyl Chlorides
2012
The preparation of -perchloroacyl chlorides, from reaction of the corresponding unfunctionalized acyl halides with chlorine, was efficiently achieved under base-catalysis, using a tetraalkylammonium chloride as catalyst. The process is solvent-free and the procedure is easy, inexpensive, and suitable for scale-up.
Cytosine methylation of tRNA-Asp by DNMT2 has a role in translation of proteins containing poly-Asp sequences
2015
AbstractThe Dnmt2 RNA methyltransferase catalyses the methylation of C38 in the anticodon loop of tRNA-Asp, but the molecular role of this methylation is unknown. Here, we report that mouse aspartyl-tRNA synthetase shows a four to fivefold preference for C38-methylated tRNA-Asp. Consistently, a 30% reduced charging level of tRNA-Asp was observed in Dnmt2 knockout (KO) murine embryonic fibroblast cells. Gene expression analysis with fluorescent reporter proteins fused to an N-terminal poly-Asp sequence showed that protein synthesis of poly-Asp-tagged reporter proteins was reduced in Dnmt2 KO cells as well. The same effect was observed with endogenous proteins containing poly-Asp sequences, i…
Peptide synthesis with 5-amino-1-methyl-1H-[1,2,4]triazole-3-carboxylic acid
2007
Abstract In the search for the peptide synthesis of new potential lexitropsins, starting with methyl 5‐amino‐1‐methyl‐1H‐[1,2,4]triazole‐3‐carboxylate 1a, we synthesized the chloroacetyl derivative of 2a, which was hydrolyzed to acid 2b and ammonolyzed to the peptide 2c. A more effective route was the use of (t‐butoxycarbonyl)glycyl‐benzotriazolide 3 to the acylation 1a, which leads the N/C protected peptide 4. This peptide was selectively N‐deprotected to be the useful segment 5 for further peptide syntheses to the N‐terminus. It was also C‐deprotected, that is hydrolyzed to give peptide 2c for further C‐extension. To the best of our knowledge, this is the first peptide that is a derivativ…
New electrophilic reactions of 2,2′-bisindolyls with acid chlorides and carbodienophiles
1996
Some new acylation and cyclization reactions of 2,2′-bisindolyls 1, 2 are described. The product patterns constitute acyl derivatives 3, 4, 5 and an aldehyde 7, indolo[2,3-a]carbazoles 6, 14, 17, 19, 20 and cyclopentadiindoles 22 and 24. In the reaction with aryne or diazotated anthranilic acid, a 3-benzoylindole derivative 9 and phenylindolyl azo dye 10 are formed. N-methylmaleimide reacts with 2,2′-bisindolyl 2 via Michael type addition, dehydrogenation and cyclization to several functionalized or anellated indole derivatives 11, 12, 13 and 14, respectively.
HPLC in the characterisation of conformational species of linear gramicidins
1997
Abstract High-performance size-exclusion chromatography (HPSEC) has proved to be a highly simplified and rapid procedure to investigate the conformational behaviour of gramicidin A inserted in different model membrane systems (lipid dispersions, liposomes, micelles) based on the separation of double-stranded dimers and monomers present in the lipid assemblies. The HPSEC approach has been extended to the characterisation of acylated analogs of gramicidin (palmitoyl- and oleoyl-derivatives) and a series of peptide analogs where tryptophan residues were chemically modified or replaced by less polar residues (phenylalanine or naphtylalanine) lacking H-bonding ability. The Chromatographic result…
Combretastatin Analogs via Hydration of Stilbene Derivatives
1993
Hydration of the double bond of some stilbene congeners of Picea abies bark by TiCl4·NaBH4 reagent is described. Five racemic 1,2-diphenylethanol derivatives (9–13), structurally related to (R)-(·)-combretastatin [(R)-1], have been obtained and characterized mainly by 13C- and 1H-NMR as well as mass spectrometry. The antileukemic activity of each compound has preliminarily been tested by the mouse leukemia L1210 system. Compound 10 has been synthesized by Friedel-Crafts acylation.