Author: Ибрагимова, М.; Рейимбердиева, М.А.; Эшчанов, Х.О.; Душамов, Д.А.

Annotation: The reaction of 3-chloroacetylbenzothiazolin-2-thione with secondary amines (diethylamine, di-n-butylamine, morpholine, and piperidine) was studied. In all cases, the reaction proceeded via an alternative pathway leading to 2-(N,N-dialkylamidomethyl)thiobenzothiazoles, instead of the expected nucleophilic substitution at chlorine. In contrast, the corresponding 3-chloroacetylbenzothiazolin-2-one underwent direct nucleophilic substitution. DFT (B3LYP) calculations indicate that replacement of the carbonyl oxygen by sulfur causes redistribution of electron density and frontier molecular orbitals, weakening the acyl linkage and promoting acyl cleavage followed by S-alkylation. These results highlight the decisive role of the thiocarbonyl group in governing the reaction pathway.

Keywords: benzothiazolin-2-thione; benzothiazolin-2-one; secondary amines; nucleophilic substitution; acyl cleavage; S-alkylation; DFT; B3LYP.

Pages in journal: 589 - 603