Hydrazones 62. The structures of aroylhydrazones with intramolecular hydrogen bonding

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

“…Therefore, in contrast to the products of the condensation of aldehydes with the hydrazides of 2-hydroxy-and 2-aminobenzoic acids reported in the literature [8] [9], 2-mercaptobenzoylhydrazones of aliphatic and aromatic aldehydes display a tendency to cyclize to give the seven-membered 1,3,4-benzothiadiazepine A. Y. Ershov et al…”

“…We note that the hydrazones obtained using the hydrazides of 2-hydroxy-and 2-aminobenzoic acids have linear structure. The possible cyclization at the C=N bond by attack of the available OH or NH functions does not occur [8] [9].…”

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

“…Examination of the 1 H NMR spectra over time showed that 2a-f exist in the cyclic thiadiazepine form in the crystalline state. The 1 H NMR spectra of 2a-f taken immediately after dissolution in DMSO-d 6 show a single set of resonance signals corresponding to this form. This conclusion is indicated by finding two NH proton signals at 5.70 and 9.45 ppm and a signal with corresponding multiplicity at 4.50 ppm (H-2) ( Table 2).…”

“…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]. In the present work, we studied the structure of the thiosalicyloylhydrazones of a series of aliphatic aldehydes 2a-f and their tendency to undergo reversible intramolecular cyclization, leading to the formation of a seven-membered 1,3,4-thiadiazepine ring.…”

“…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…”