1,721,043 research outputs found
Synthesis of Oligomers oftrans-(4S,5R)-4-Carboxybenzyl 5-Methyl Oxazolidin-2-one: An Approach to New Foldamers
No full textThe synthesis of two oligomers containing three and four residues, respectively, of trans-(4S,5R)-4-carboxy 5-methyloxazolidin-2-ones is described. The monomer is obtained by starting from benzyl-N-Boc-(3R)-aminobutanoate, by cyclization into the corresponding trans-(2S,3R)-2-carboxybenzyl-3-methyl-N-Boc-aziridine and rearrangement of the product to trans-(4S,5R)-4-carboxybenzyl-5-methyloxazolidin-2-one, catalyzed by Sn(OTf)2. The oligomers are synthesized by activating the carboxy group as its pentaflourophenyl ester. The trimer and the tetramer are obtained in good yield, and their 1H NMR spectra suggest that these molecules fold in ordered structures, where the C-4 hydrogen of a ring is always close to the carbonyl of the next ring. This result shows that the 4-carboxy-5-substituted-oxazolidin-2-ones are a new class of pseudoprolines which fully control the formation of a Xaai-1-Proi peptide bond in the trans conformation and are complementary to the pseudoprolines obtained from cyclocondensation of cysteine, serine, or threonine and aldehydes or ketones, which strongly favor the Xaai-1-Proi peptide bond in the cis conformation
Pharmacokinetic and pharmacodynamic evaluation of ramelteon : an insomnia therapy
No full textRamelteon , a selective melatonin receptor agonist, is the first member of a novel class of hypnotics. It is approved for the treatment of insomnia characterized by sleep onset difficulties in the US and Japan, but not in Europe
METHOD FOR PRODUCING OPTICALLY ACTIVE 1,2-DIAMINE COMPOUND AND OPTICALLY ACTIVE NIOBIUM CATALYST
No full textTo provide a method for producing an optically active 1,2-diamine compound in high yield and high stereoselectivity using a niobium catalyst having an optically active polyhydric alcohol as a ligand and to provide the optically active niobium catalyst. ;SOLUTION: An optically active aziridine compound is reacted with an aromatic amine compound in a reaction system obtained by mixing a niobium compound with an optically active tetrol represented by formula (I) or an antipode thereof in an organic solvent. Thereby, the optically active 1,2-diamine compound is produced
Organocatalyzed coupling of indoles with dehydroalanine esters: synthesis of bis(indolyl)propanoates and indolacrylates
Full text linkFunctionalized and substituted bis(indolyl)alkanes were synthesized from indoles and dehydroalanine esters in the presence of catalytic amounts of Brønsted acid. When 2- or 4-bulky substituted indoles were used, unusual elimination occurred to yield interesting indolyl acrylates
An improved synthesis of cis-4-phenyl-2-propionamidotetralin (4-P-PDOT): a selective MT2 melatonin receptor antagonist.
No full textA novel, efficient and diastereoselective procedure was developed for the gram-scale synthesis of cis-4-phenyl-2-propionamidotetralin (4-P-PDOT), a selective MT2melatonin receptor antagonist. The synthetic strategy involved the conversion of 4-phenyl-2-tetralone to enamide followed by diastereoselective reduction affording cis-4-P-PDOT in good yield. The mechanism of the reduction step was explored by employing deuterated reagents
Derivatizzazione one-pot di indoli per la sintesi di triptofani, pirroloindoline, bis-indoli & co
No full textL’anello indolico rappresenta uno dei più importanti ed abbondanti eterocicli presenti in natura.Lo si può trovare in una miriade di composti naturali, dal semplice neurotrasmettitore serotonina agli alcaloidi più complessi. Lo “scaffold” indolico è contenuto inoltre in molti farmaci sintetici presenti in commercio per un valore di mercato di circa 3.2 miliardi di dollari nel mondo nel 2010, promuovendo l’indolo a “struttura privilegiata”. Da queste considerazioni appare evidente l’esigenza di un continuo sviluppo di nuovi protocolli sintetici per la derivatizzazione del nucleo indolico.
La presentazione orale verterà sulle metodologie sviluppate nel nostro gruppo di ricerca negli ultimi anni per la sintesi di nuovi composti naturali e non contenenti il nucleo indolico e lo studio delle loro attività biologiche, in particolare in ambito antitumorale
Synthesis of Boron- and Silicon-Containing Amino Acids through Copper-Catalysed Conjugate Additions to Dehydroalanine Derivatives
Full text linkA copper-based catalytic technique for the regioselective hydroboration and hydrosilylation of dehydroalanine derivatives has been developed. This method introduces synthetically versatile boron and silicon groups, while simultaneously performing a catalytic anti-Markovnikov hydrofunctionalization of dehydroalanines and dehydropeptides for the synthesis of amino acids and peptides bearing unnatural side-chains. The products obtained were expediently converted into valuable nonproteinogenic amino acid building blocks for polypeptide synthesis
Marine Alkaloid 2,2-Bis(6-bromo-3-indolyl) Ethylamine and Its Synthetic Derivatives Inhibit Microbial Biofilms Formation and Disaggregate Developed Biofilms
Full text linkThe antimicrobial activity of the marine bisindole alkaloid 2,2-bis(6-bromo-3-indolyl) ethylamine (1) and related synthetic analogues (compounds 2–8) against target microorganisms was investigated by Minimum Inhibitory Concentration (MIC) determination. Compound 1 showed the greatest antimicrobial activity with the lowest MIC (8 mg/L) against Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae, while the derivatives exhibited higher MICs values (from 16 to 128 mg/L). Compounds 1, 3, 4, and 8, the most active ones, were then tested against E. coli, S. aureus, K. pneumoniae, and Candida albicans during biofilms formation as well as on 24 h developed biofilms. The natural alkaloid 1 inhibited the biofilm formation of all the tested microorganisms up to 82.2% and disaggregated biofilms of E. coli, S. aureus, K. pneumoniae, and C. albicans after 30 min of contact, as assessed by viable plate count and crystal violet (CV) staining (optical density at 570 nm). Synthetic derivatives 3, 4, and 8 displayed anti-biofilm activity toward individual bacterial populations. This study highlights the potential of marine bisindole alkaloid 1 as anti-biofilm agent and shows, through a preliminary structure activity relationship (SAR), the importance of halogens and ethylamine side chain for the antimicrobial and antibiofilm activities of this bisindole series
A Versatile Biomimetic Approach to Diindolylmethane Derivatives as Potential Anticancer Agents
No full textSwitchable reactivity of acylated alpha, beta-dehydroamino ester in the Friedel-Crafts alkylation of indoles by changing the Lewis acid.
No full textHighly regioselective electrophilic substitution of indoles with N-acetylated α,β-dehydroalanine methyl ester, promoted by different transition metal salts was achieved. The orthogonal regioselectivity provides an efficient protocol toward highly functionalized 3-indolyl-α-amino acids. The mechanism of the reactions was explored by NMR studies
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