The tendency of functionally-substituted hydrazones to undergo intramolecular cyclization at the polar C=N bond of the hydrazone fragment is commonly used in the synthesis of five-and six-membered heterocycles [1,2]. This reaction is sometimes reversible, which leads to the coexistence of the hydrazone and cyclic forms as their tautomeric mixture in solution [3,4]. Thus, the thiosalicyloylhydrazone of acetone obtained in our laboratory transforms in solution to the alternative 1,3,4-benzothiadiazepine form [5]. We note that the hydrazones obtained using the hydrazides of salicylic and anthranilic acids have linear structure. The possible cyclization at the C=N bond by attack of the available OH or NH functions does not occur [6,7]. SH N NH 2 O H SH N H H N O R S N NH O H R RCH O 2a-f B E,Z'-A 1 2 a R = Me, b R = Et, c R = Pr, d R = Bu, e R = i-Pr, f R = i-Bu