Quantum chemical studies on some potentially tautomeric thiazolidinone derivatives and their thio and azo analogs

Cemil Öğretir,Nesrin Tokay

doi:10.3998/ark.5550190.0009.e10

Abstract

The gas phase semi-empirically calculated relative stability and tautomeric equilibrium values revealed that 2C, 4C, and 5C hydroxy substituted thiazolidinone derivatives prefer oxo forms. The 2C, 4C, and 5C mercapto substituted derivatives also found to prefer the thione forms. On the contrary 2C, 4C, and 5C amino substituted derivatives were found to prefer amino forms.

Highlights

It has been well known that thiazole derivatives play very important roles in biochemical reactions such as oxidative decarboxylation and formation of α-hydroxyalkyl ketons called acyloins.[1]
We believe that this gap should be filled up to a certain extent by studying the tautomeric equilibria of some potentially tautomeric thiazole derivatives following our work on tautomerism, isomerism and deprotonation of some 5(6)-substituted benzimidazole-2-thione derivatives[2] we reporting on some quantum chemical studies on potentially tautomeric thiazolidinone derivatives and their thio and azo analogs
The solvent effect was included in the geometry optimizations following the ‘COnductor-like Screening MOdel’ (COSMO)[8] implemented in MOPAC 7.0

Summary

Introduction

It has been well known that thiazole derivatives play very important roles in biochemical reactions such as oxidative decarboxylation and formation of α-hydroxyalkyl ketons (i.e. structural change) called acyloins.[1]. When a potentially tautomeric mercapto group is placed at 2C, 4C, and 5C (molecules 4, 5, and 6) of thiazolidine molecules the gas phase stability studies with all four methods indicate that the main tautomers exist in the thione forms a rather than thiol forms b.

Results

Conclusion