Thiosalicyloylhydrazones of aliphatic aldehydes and their cyclization to give 1,3,4-benzothiadiazepine derivatives

Abstract

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

Ring-Chain Tautomerism of the Condensation Products of 2-Mercaptobenzohydrazide with Aliphatic and Aromatic Aldehydes: Influence of Electronic and Steric Factors

“…Physico-chemical and spectral characteristics of compounds 2b-2f and 3a-3c, 3e-3h were described previously [23] [24]. …”

Structure of Aldoses Condensation Products with SH-Containing Hydrazides

“…The aim of the present work was to study of the structure of the condensation products of aldoses with hydrazides of thiobenzoic (PhCSNHNH 2 ), sulfanylacetic (HSCH 2 CONHNH 2 ), 3-sulfanylpropionic (HSCH 2 CH 2 CONHNH 2 ), and 2-sulfanylbenzoic (2-HSC 6 …”