Search results for " amines"
showing 10 items of 43 documents
Stereoselective cathodic synthesis of 8-substituted (1R,3R,4S)-menthylamines.
2015
The electrochemical generation of menthylamines from the corresponding menthone oximes equipped with an additional substituent in position 8 is described. Due to 1,3-diaxial interactions a pronounced diastereoselectivity for the menthylamines is found.
Predicting and Tuning Physicochemical Properties in Lead Optimization: Amine Basicities
2007
This review describes simple and useful concepts for predicting and tuning the pK(a) values of basic amine centers, a crucial step in the optimization of physical and ADME properties of many lead structures in drug-discovery research. The article starts with a case study of tricyclic thrombin inhibitors featuring a tertiary amine center with pK(a) values that can be tuned over a wide range, from the usual value of around 10 to below 2 by (remote) neighboring functionalities commonly encountered in medicinal chemistry. Next, the changes in pK(a) of acyclic and cyclic amines upon substitution by fluorine, oxygen, nitrogen, and sulfur functionalities, as well as carbonyl and carboxyl derivativ…
Synthesis of Densely Functionalised 5-Halogen-1,3-oxazin-2-ones byHalogen-Mediated Regioselective Cyclisation of N-Cbz-ProtectedPropargylic Amines: A…
2013
A very efficient synthesis of 5-halogen-1,3-oxazin-2-ones has been accomplished by the halocyclisation reaction of chiral nonracemic N-carbobenzyloxy (N-Cbz)-protected propargylic amines by using I-2, Br-2 and Cl-2 as electrophile sources. The nature of the halogen influences the reaction time and yield. However, in all cases the reaction is totally regioselective taking place through a 6-endo-dig process regardless of the nature of the halogen and of the substituents in the starting material. To rationalise the experimental results, theoretical studies at the B3LYP/6-311G* level have been performed.
13C-NMR Based Evaluation of the Electronic and Steric Interactions in Aromatic Amines
2005
Abstract: Chemical shifts of the para carbon atoms, δ(13C-4), in a series of aromatic amines were used to calculate the Ãp, ÃR and ÃOR substituent constants for different amino groups. 1-Pyrrolidino, N,N-di-n-butylamino and N,N-diethylamino groups were found to be the most strong electron-donors. ortho-Substitution decreases the donor properties of the amino group. The amino groups in 2,6-di-i-propylaniline and N,N-2,6-tetramethylaniline have very weak electron-donor properties. The nitrogen atom in benzoquinuclidine and N,N-dimethyl-2,6-di-i-propylaniline have an electron-acceptor character. The calculated substituent constants of the amino groups studied are consistent with the s…
Straightforward preparation of highly loaded MWCNT-polyamine hybrids and their application in catalysis
2020
Multiwalled carbon nanotubes (MWCNTs) were easily and efficiently functionalised with highly cross-linked polyamines. The radical polymerisation of two bis-vinylimidazolium salts in the presence of pristine MWCNTs and azobisisobutyronitrile (AIBN) as a radical initiator led to the formation of materials with a high functionalisation degree. The subsequent treatment with sodium borohydride gave rise to the reduction of imidazolium moieties with the concomitant formation of secondary and tertiary amino groups. The obtained materials were characterised by thermogravimetric analysis (TGA), elemental analysis, solid state 13C-NMR, Fourier-transform infrared spectroscopy (FT-IR), transmission ele…
Study of biogenic amines metabolism in wine lactic acid bacteria
2011
Biogenic amines are indesirable compounds found in fermented products like wine. Lactic acid bacteria from wine, including Oenococcus oeni, the main actor of malolactic fermentation, are able to produce these molecules from nitrogenous precursors. In order to limited biogenic amines accumulation, it is necessary to understand the role of this production by strains responsible for the synthesis of these metabolites in food. That is why the European BiamFood project was put in place. Along my thesis, molecular tools were developed in order to mutate O. oeni genes (encoding decarboxylases), and to express genes of interest. Genetic clusters hdc from L. higardii and odc from O. oeni, responsibl…
Evolution of Free Amino Acids, Histamine and Volatile Compounds in the Italian Anchovies (Engraulis encrasicolus L.) Sauce at Different Ripening Times
2022
In this study, the evolution of the safety, nutritional, and volatile profile of a traditional Italian anchovy sauce with protected designation of origin (PDO), called “colatura di alici di Cetara”, is investigated after 12, 24, and 48 months of aging in wooden barrels. Some physicochemical parameters, free amino acids, volatile compounds, and histamine contents were evaluated during the aging of the samples. Glutamate, which together with aspartate is responsible for the umami taste, was the predominant free amino acid in the tested fish sauce, with a significant increase during the 48 months of maturation. The total amino acid content of the anchovy sauce increased from 24 to …
Study of aromatic nucleophilic substitution with amines on nitrothiophenes in RTILs: are the different effects on the behavior of para-like and orto-…
2006
The kinetics of the nucleophilic aromatic substitution of some 2-L-5-nitrothiophenes (para-like isomers) with three different amines (pyrrolidine, piperidine, and morpholine) were studied in three roomtemperature ionic liquids ([bmim][BF4], [bmim][PF6], and [bm2im][BF4], where bmim ) 1-butyl-3- methylimidazolium and bm2im ) 1-butyl-2,3-dimethylimidazolium). To calculate thermodynamic parameters, a useful instrument to gain information concerning reagent-solvent interactions, the reaction was carried out over the temperature range 293-313 K. The reaction occurs faster in ionic liquids than in conventional solvents (methanol, benzene), a dependence of rate constants on amine concentration sim…
Pressor amines in coronary artery bypass grafting procedure with and without the use of extracorporeal circulation
2017
Wstęp: Operacje rewaskularyzacji mięśnia sercowego są najczęściej wykonywanymi procedurami w praktyce kardiochirurgicznej. Rozwój technik pomostowania tętnic wieńcowych bez użycia krążenia pozaustrojowego spowodował, iż modyfikacjom uległy również techniki znieczulenia. W prowadzeniu znieczulenia do zabiegów typu OPCA B anestezjolog musi szczególnie szybko reagować na częste, czasem nieprzewidywalne zmiany sytuacji hemodynamicznej. Cel pracy: Celem pracy było porównanie zastosowania amin presyjnych wśród pacjentów poddanych chirurgicznej rewaskularyzacji mięśnia sercowego z krążeniem pozaustrojowym i bez niego. Materiał i metody: Badanie miało charakter retrospektywny. Badaniem objęto 80 ch…
Sequestration of biogenic amines by alginic and fulvic acids.
2006
The interaction of natural (alginic and fulvic acids) and synthetic (polyacrylic acid 2.0 kDa) polyelectrolytes with some protonated polyamines [diamines: ethylendiamine, 1,4-diaminobutane (or putrescine), 1,5-diaminopentane (or cadaverine); triamines: N-(3-aminopropyl)-1,4diaminobutane (or spermidine), diethylenetriamine; tetramine: N.N'-bis(3-aminopropyl)-1,4-diaminobutane (or spermine); pentamine: tetraethylene-pentamine; hexamine: pentaethylenehexamine] was studied at T=25 degrees C by potentiometry and calorimetry. Measurements were performed without supporting electrolyte, in order to avoid interference, and results were reported at I=0 mol L(-1). For all the systems, the formation of…