1262533-73-2Relevant academic research and scientific papers
Annelated pyridines as highly nucleophilic and Lewis basic catalysts for acylation reactions
Tandon, Raman,Unzner, Teresa,Nigst, Tobias A.,De Rycke, Nicolas,Mayer, Peter,Wendt, Bernd,David, Olivier R. P.,Zipse, Hendrik
, p. 6435 - 6442 (2013)
New heterocyclic derivatives of 9-azajulolidine have been synthesized and characterized with respect to their nucleophilicity and Lewis basicity. The Lewis basicity of these bases as quantified through their theoretically calculated methyl-cation affinities correlate well with the experimentally measured reaction rates for addition to benzhydryl cations. All newly synthesized pyridines show exceptional catalytic activities in benchmark acylation reactions, which correlate only poorly with Lewis basicity or nucleophilicity parameters. A combination of Lewis basicity with charge and geometric parameters in the framework of a three-component quantitative structure-activity relationship (QSAR) model is, however, highly predictive. Copyright
Photogeneration of benzhydryl cations by near-UV laser flash photolysis of pyridinium salts
Nigst, Tobias A.,Ammer, Johannes,Mayr, Herbert
, p. 8494 - 8499 (2013/01/14)
Laser flash irradiation of substituted N-benzhydryl pyridinium salts yields benzhydryl cations (diarylcarbenium ions) and/or benzhydryl radicals (diarylmethyl radicals). The use of 3,4,5-triamino-substituted pyridines as photoleaving groups allowed us to employ the third harmonic of a Nd/YAG laser (355 nm) for the photogeneration of benzhydryl cations. In this way, benzhydryl cations can also be photogenerated in the presence of aromatic compounds and in solvents which are opaque at the wavelength of the quadrupled Nd/YAG laser (266 nm). To demonstrate the scope and limitations of this method, the rate constants for the bimolecular reactions of benzhydryl cations with several substituted pyridines were determined in acetonitrile and with water in acetone. The obtained data agree with results obtained by stopped-flow UV-vis spectroscopic measurements. The rate constants for the reaction of the 4,4'-bis[methyl(2,2,2- trifluoroethyl)amino]benzhydrylium ion with 4- (dimethylamino)pyridine were also determined in dimethyl sulfoxide, N,N-dimethylformamide, and acetone. From the secondorder rate constants, we derived the nucleophilicity parameters N and sN for the substituted pyridines, as defined by the linear free energy relationship, log k2 = sN(N + E).
Synthesis and reactivity of highly nucleophilic pyridines
De Rycke, Nicolas,Berionni, Guillaume,Couty, Francois,Mayr, Herbert,Goumont, Regis,David, Olivier R. P.
, p. 530 - 533 (2011/03/23)
3,4,5-Triamino-substituted pyridines are avid for electrophiles but are still willing to give them back. In these compounds three amino groups conjoin their forces into the heterocyclic nitrogen, making it a powerful Lewis base. A short and efficient synt
