Polynuclear tetrazole-containing amino acid analogs

New analogs of (D,L)-phenylalanine containing tetrazole rings were synthesized. The acidity constants of (D, L)-phenylalanine and (D,L)-tryptophane derivatives containing a tetrazole ring with no substituent on N¹ (pK _a = 3.0–3.1) and of the corresponding carboxylic acids (pK _a = 2.9–3.3) in aqueous methanol were determined by potentiometric titration.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 10, 2004, pp. 1576–1579.Original Russian Text Copyright © 2004 by Morozova, Esikov, Zubarev, Malin, Ostrovskii.