4028-52-8Relevant academic research and scientific papers
Micellar Effects upon the Rates of SN2 Reactions of Halide Ions
Al-Lohedan, Hamad A.
, p. 8226 - 8231 (1990)
Observed first-order rate constants for reactions of Cl- or Br- with alkyl benzenesulfonate (1a-c) in micelles of cetyltrimethylammonium surfactants (CTAX, X=Cl, Br, OMes, 0.5SO4) increase monotonically with increasing or or halide ion concentration and tend to limiting values.In CTAOMes or (CTA)2SO4, the rate constants go through maxima.The variation of the rate constants with concentrations of surfactant and halide ion can be fitted to an equation that accounts for the distribution of both reactants between water and micelles, i. e., in terms of ion-exchange and mass-action models.The second-order rate constants in the aqueous and micellar pseudophases are similar.
Effect of Partially Fluorinated N-Alkyl-Substituted Piperidine-2-carboxamides on Pharmacologically Relevant Properties
Vorberg, Raffael,Trapp, Nils,Zimmerli, Daniel,Wagner, Bj?rn,Fischer, Holger,Kratochwil, Nicole A.,Kansy, Manfred,Carreira, Erick M.,Müller, Klaus
, p. 2216 - 2239 (2016/10/19)
The modulation of pharmacologically relevant properties of N-alkyl-piperidine-2-carboxamides was studied by selective introduction of 1–3 fluorine atoms into the n-propyl and n-butyl side chains of the local anesthetics ropivacaine and levobupivacaine. The basicity modulation by nearby fluorine substituents is essentially additive and exhibits an exponential attenuation as a function of topological distance between fluorine and the basic center. The intrinsic lipophilicity of the neutral piperidine derivatives displays the characteristic response noted for partially fluorinated alkyl groups attached to neutral heteroaryl systems. However, basicity decrease by nearby fluorine substituents affects lipophilicities at neutral pH, so that all partially fluorinated derivatives are of similar or higher lipophilicity than their non-fluorinated parents. Aqueous solubilities were found to correlate inversely with lipophilicity with a significant contribution from crystal packing energies, as indicated by variations in melting point temperatures. All fluorinated derivatives were found to be somewhat more readily oxidized in human liver microsomes, the rates of degradation correlating with increasing lipophilicity. Because the piperidine-2-carboxamide core is chiral, pairs with enantiomeric N-alkyl groups are diastereomeric. While little response to such stereoisomerism was observed for basicity or lipophilicity, more pronounced variations were observed for melting point temperatures and oxidative degradation.
ZnO and ZnO-nanoparticles: Efficient and reusable heterogeneous catalysts for one-pot synthesis of N-acylsulfonamides and sulfonate esters
Tamaddon, Fatemeh,Sabeti, Mohammad Reza,Jafari, Abbas Ali,Tirgir, Farhang,Keshavarz, Elham
experimental part, p. 41 - 45 (2012/01/12)
Commercially available and preparative ZnO nanoparticles are reported as efficient and reusable catalysts for the chemoselective synthesis of N-acylsulfonamides and sulfonate esters. A one-pot sequential sulfonylation and acylation of amines took place to afford the N-acylsulfonamides in excellent yields under solvent-free conditions. The ZnO catalyst can be reused for without significant loss of catalytic activity.
Inscribing the perimeter of the PagP hydrocarbon ruler by site-specific chemical alkylation
Khan, M. Adil,Moktar, Joel,Mott, Patrick J.,Vu, Mary,McKie, Aaron H.,Pinter, Thomas,Hof, Fraser,Bishop, Russell E.
experimental part, p. 9046 - 9057 (2011/11/04)
The Escherichia coli outer membrane phospholipid:lipid A palmitoyltransferase PagP selects palmitate chains using its β-barrel-interior hydrocarbon ruler and interrogates phospholipid donors by gating them laterally through an aperture known as the crenel. Lipid A palmitoylation provides antimicrobial peptide resistance and modulates inflammation signaled through the host TLR4/MD2 pathway. Gly88 substitutions can raise the PagP hydrocarbon ruler floor to correspondingly shorten the selected acyl chain. To explore the limits of hydrocarbon ruler acyl chain selectivity, we have modified the single Gly88Cys sulfhydryl group with linear alkyl units and identified C10 as the shortest acyl chain to be efficiently utilized. Gly88Cys-S-ethyl, S-n-propyl, and S-n-butyl PagP were all highly specific for C12, C11, and C10 acyl chains, respectively, and longer aliphatic or aminoalkyl substitutions could not extend acyl chain selectivity any further. The donor chain length limit of C10 coincides with the phosphatidylcholine transition from displaying bilayer to micellar properties in water, but the detergent inhibitor lauryldimethylamine N-oxide also gradually became ineffective in a micellar assay as the selected acyl chains were shortened to C10. The Gly88Cys-S-ethyl and norleucine substitutions exhibited superior C12 acyl chain specificity compared to that of Gly88Met PagP, thus revealing detection by the hydrocarbon ruler of the Met side chain tolerance for terminal methyl group gauche conformers. Although norleucine substitution was benign, selenomethionine substitution at Met72 was highly destabilizing to PagP. Within the hydrophobic and van der Waals-contacted environment of the PagP hydrocarbon ruler, side chain flexibility, combined with localized thioether-aromatic dispersion attraction, likely influences the specificity of acyl chain selection.
