Mesoiônicos da Classe 1,3-Ditiólio-4-Tiolatos: síntese, reações de cicloadição 1,3-Dipolar e estudo do efeito hidrofóbico

Abstract

The mesoionic compounds have been receiving much attention because of their dipolar special structures and wide-ranging biological activities, they have also being utilized as cycloaddition reactions intermediates to afford new heterocyclic derivatives. In this work 17 new mesoionic derivatives were synthesised from the 1,3- dithiolium-4-thiolate class, including a homologous series of 13 2-N-morpholino-5- alkyl-1,3-dithiolium-4-thiolate. The 2-N-morpholino-5-ethyl- and 2-N-morpholino-5-tetradecyl-1,3- dithiolium-5-thiolates were submitted at 1,3-dipolar cycloaddition reactions against DMAD and phenylpropiolic acid as dipolarophiles affording 8 new thiophenic derivatives. The experimental results were in agreement with the theoretical studies employing semi-empirical molecular modelling methods. All heterocyclic derivatives were fully characterised by spectroscopic techniques, IR, 1H and 13C NMR (1D and 2D experiments) and MS. The UV spectroscopy was utilised only for the homologous mesoionic series. The mesoionic derivatives were assayed against Artemia salina Leach in the general toxicity tests. The hydrophobic effect was studied on mesoionic derivatives of the 5-alkyl homologous series, correlating the Artemia salina general toxicity versus lateral chain number carbon atoms, and the logP values. The results indicated a bell-shaped relationship between the number of carbon of side chain in mesoionic derivatives and LD50 in brine shrimp toxicity assays. The experimental results were in agreement with the theoretical studies which were employing semi-empirical molecular modelling methods. All heterocyclic derivatives were fully characterized by spectroscopic techniques, IR, 1H and 13C NMR (1D and 2D experiments), and MS. The UV spectroscopy was utilized only for the homologous mesoionic series