- Flow-Assisted Synthesis of Bicyclic Aziridines via Photochemical Transformation of Pyridinium Salts
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Herein is described the development and comparison of homemade continuous-flow reactors, a fluorinated ethylene propylene tube (FEP) reactor (internal diameter of 0.4 cm) and two parallel quartz reactors containing two different internal diameters (0.4 and 0.2 cm), and their application to the photochemical transformation of 1-n-butyl- and 1-allylpyridinium bromide salts (1a and 1b, respectively) to the corresponding α-hydroxycyclopentenoaziridines (6-azabicyclo[3.1.0]hex-3-en-2-ols) 2a and 2b. Under recirculating conditions, the FEP reactor allowed the production of a greater quantity of bicyclic aziridine (3.2 g), while the quartz reactor with the same diameter furnished the best productivity results (3.7 g L-1 h-1). In addition, the FEP reactor operated efficiently under circulating conditions (1.75 L of 1a) for 4.5 days (residence time of 17.9 h), allowing the production of 2a at a rate of 2 g/day (62-93% conversion).
- Siopa, Filipa,António, Joao P. M.,Afonso, Carlos A. M.
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- Polycations-12. The synthesis of liquid ionic phosphates (lips) from mono- and polycationic ammonium halides
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Preparations are reported for an extensive series of phosphate salts of polyammonium species from the corresponding halide salts. The phosphate salts, as anhydrous materials, are liquid at or near room temperature. Three approaches for the preparation of these materials are noted, including treatment with aqueous hexafluorophosphoric acid, classical ion exchange methods, and treatment with 85% phosphoric acid. The last of these provides the most desirable results. Several monocationic phosphate salts have also been prepared for comparison with other types of ionic liquids.
- Lall, Sharon,Behaj, Valbona,Mancheno, Danny,Casiano, Robert,Thomas, Marie,Rikin, Amir,Gaillard, Jennifer,Raju, Ravinder,Scumpia, Alexander,Castro, Steve,Engel, Robert,Cohen, JaimeLee Iolani
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- Spectroscopic study of reaction of propargyl bromide with pyridine
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Pyridine was reacted with propargyl bromide to obtain the dibromide [C 5H5NCH=CHCH=CHCH=CHC5H5N] 2+ 2Br-. The effect of the vinyl group on its UV spectrum is qualitatively interpreted using the results of nonempirical quantum-chemical calculations (basis HF/6-31G*).
- Kanitskaya,Elokhina,Fedorov,Shulunova,Nakhmanovich,Turchaninov,Lopyrev
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- Preparation, in vitro screening and molecular modelling of mono-quaternary compounds related to the selective acetylcholinesterase inhibitor BW284c51
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This paper describes preparation and in vitro evaluation of 19 compounds related to the selective experimental cholinesterase inhibitor BW284c51. The novel compounds were prepared as fragments of parent molecule BW284c51 and evaluated on the model of human recombinant acetylcholinesterase and human plasmatic butyrylcholinesterase. The IC50 values of the prepared compounds were compared to the parent molecule BW284c51. None of the compounds was superior to the parent drug, but two BW284c51 fragments showed promising hAChE inhibition in μM scale and improved selectivity. These two fragments were further subjected to the molecular modelling study and their enzyme interactions were rationalized. The structure-activity relationship of the prepared series was stated.
- Benek, Ondrej,Musilek, Kamil,Horova, Anna,Dohnal, Vlastimil,Dolezal, Rafael,Kuca, Kamil
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- Dynamic Covalent Chemistry of Nucleophilic Substitution Component Exchange of Quaternary Ammonium Salts
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Dynamic covalent libraries (DCLs) of quaternary ammonium cations were set up by reversible nucleophilic substitution (SN2′ and SN2) exchange reactions of ammonium salts and tertiary amines. The reactions were conducted at 60 °C to generate thermodynamically and kinetically controlled mixtures of quaternary ammonium compounds and tertiary amines, and were accelerated by using iodide as a nucleophilic catalyst. Microwave irradiation was used to assist the exchange reaction between the pyridinium salts and pyridine derivatives. Finally, experiments towards the generation of dynamic ionic liquids were performed. The results of this study pave the way for the extension of dynamic combinatorial chemistry to nucleophilic substitution reactions.
- Kulchat, Sirinan,Lehn, Jean-Marie
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p. 2484 - 2496
(2015/11/02)
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- Synthesis and thermal characterization of mono and dicationic imidazolium pyridinium based ionic liquids
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A series of monocationic and dicationic ionic liquids, in which each ionic liquid is associated with dicyanamide anion, are synthesized. The molecular structures of these compounds were identified by 1H-NMR, FT-IR and CHN analysis. Thermal behaviors of these ionic liquids were also investigated by thermogravimetry (TGA). The results suggested that all new ionic liquids have reasonable thermal stabilities, however, dicationic ionic liquids show more thermal stability than monocationics.
- Alamdari, Reza Fareghi,Zamani, Faezeh Ghorbani,Shekarriz, Marzieh
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p. 1127 - 1132
(2015/10/28)
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- Nitrogen-containing ionic liquids: Biodegradation studies and utility in base-mediated reactions
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Several ionic liquids (ILs) were prepared in order to study the susceptibility of various cores and substituents to biodegradability using the 'CO2 headspace' test (ISO 14593). Several of the ILs contained tertiary amine substituents and were tested as solvents and reagents for several base mediated processes including Suzuki-Miyaura, Sonogashira, Knoevenagel, and Morita-Baylis-Hilman reactions. It was found that although these ILs contain basic functionality, they do not promote base mediated reactions. Density functional theory molecular calculations confirmed that the protonation of these ILs is energetically unfavourable. Journal compilation
- Ford, Leigh,Ylijoki, Kai E.O.,Garcia, M. Teresa,Singer, Robert D.,Scammells, Peter J.
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p. 849 - 857
(2015/06/23)
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