3333-08-2Relevant articles and documents
13C Chemical Shifts and Conformational Equilibria in Quaternary Piperidinium Salts
Sugiura, Makiko,Takao, Narao
, p. 37 - 39 (1982)
Carbon-13 nuclear resonance spectra of a series of N-methyl-N-alkylpiperidinium salts have been measured, and the observed chemical shifts analysed in terms of the stereochemical and conformational properties of the molecules.Furthermore, the differences of the free energy (ΔGo) between two conformers on ring inversion have been estimated.
Cucurbit[7]uril host-guest complexes and [2]pseudorotaxanes with N-methylpiperidinium, N-methylpyrrolidinium, and N-methylmorpholinium cations in aqueous solution
Gamal-Eldin, Mona A.,MacArtney, Donal H.
, p. 1234 - 1241 (2013/03/29)
The formations of host-guest complexes between cucurbit[7]uril and a series of N-substituted N-methylpiperidinium, N-methylpyrrolidinium, and N-methylmorpholinium cations in aqueous solution have been investigated using 1H NMR spectroscopy and electrospray ionization mass spectrometry. Dications comprising the N-methylheterocyclic head groups, bridged by a decamethylene chain, form sequential 1:1 ([2]pseudorotaxanes) and 2:1 host-guest complexes with cucurbit[7]uril. The cucurbituril initially resides over the decamethylene chain, however with further additions of the host molecule a translocation of the hosts to the cationic N-heterocyclic head groups occurs. The order of the magnitude of the cucurbituril host-guest stability constants, determined by competitive 1H NMR binding experiments, follows the trend in the hydrophobicity of the quaternary ammonium cations.
Dealkylation of Quaternary Ammonium Salts by Thiolate Anions: A Model of the Cobalamin-independent Methionine Synthase Reaction.
Hilhorst, Ellen,Chen, Tjoe B. R. A.,Iskander, Atef S.,Pandit, Upendra K.
, p. 7837 - 7848 (2007/10/02)
The reactions of thiolate ions derived from thiophenol and homocysteine with substituted quaternary ammonium salts result in alkyl transfer from nitrogen to sulfur.A radical mechanism for this transalkylation, accounts for the reactivity pattern of the substrate salts.In a model study of the cobalamin-independent methionine synthase reaction, 5,5,6,7-tetramethyl-5,6,7,8-tetrahydropteridinium salt (25), which can be considered as a model for the natural coenzyme 5-CH3H4-folate (1), was allowed to react with the thiolate of homocysteine, whereupon the formation of methionine was observed in good yield.These results suggest that in the enzymatic process the N(5)-CH3 bond may be activated for the methyl transfer step, by coordination of the N(5) with an electrophile or a proton at the active site.