One-pot syntheses of 5-amino-1-aryltetrazole derivatives
A novel facile route for the introduction of 5-amino and 5-alkylamino substituents into 1-aryltetrazoles has been developed. A range of 5-amino-1-aryltetrazoles was obtained directly from the corresponding 1-aryltetrazoles in one pot by consecutive ring-opening, azidation and intramolecular cyclization. 5-Alkylamino-1-aryltetrazoles were formed by a similar mechanism from 1,4-disubstituted tetrazolium salts. An influence of the nature of aryl substituents and reaction conditions on the regioselectivity of the intramolecular cyclization of intermediate guanyl azides is revealed. Georg Thieme Verlag Stuttgart.
Vorobiov, Andrey N.,Gaponik, Pavel N.,Petrov, Petr T.,Ivashkevich, Oleg A.
p. 1307 - 1312
(2007/10/03)
On the Physicochemical Characterization of 5-Amino-1-aryl-1H-tetrazoles: Electronic Molecule Parameters from the Thermal Isomerization into 5-Arylamino-1H-tetrazoles
The known thermal isomerization of 5-amino-1-aryl-1H-tetrazoles (A) into corresponding 5-arylamino-1H-tetrazoles (HB) was used to derive physicochemical parameters characterizing the electronic substituent effect on isomerism and dissociation equilibria. For a series of 26 tetrazoles A as starting materials the equilibrium constants (pKi) of isomerization in boiling ethylene glycol at 197°C and the dissociation constants (pKa) of the NH-acidic tetrazoles HB were determined by potentiometric titration of rapidly cooled equilibrium mixtures in water and ethanol/water with KOH at 25°C. The pK values are closely correlated with Hammett's electronic substituent constants σ and can be used as electronic molecule parameters in QSAR or QSPR (QSAR = quantitative structure-activity relationship; QSPR = quantitative structure-property relationship) studies.
Schelenz, Thomas,Schaefer, Wieland
p. 197 - 200
(2007/10/03)
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