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Synthesis and Characterization of some New Mesoionic 1,3-Thiazolium-5-thiolates via Cyclodehydration and in situ 1,3-Dipolar Cycloaddition/Cycloreversion

Author(s): Bruno Freitas Lira | Petrônio Filgueiras de Athayde Filho | Joseph Miller | Alfredo Mayall Simas | Aderson de Farias Dias | Maria Joaquina Vieira

Journal: Molecules
ISSN 1420-3049

Volume: 7;
Issue: 11;
Start page: 791;
Date: 2002;
Original page

Keywords: Mesoionic 1 | 3-thiazolium-5-thiolates | Synthesis | Characterization

The title compounds were synthesized from C-aryl-N-methylglycines by Naroylation followed by a cyclodehydration to form the corresponding 1,3-oxazolium-5-olates. These were not isolated but converted to the title compounds by an in situ 1,3-dipolar cycloaddition/cycloreversion sequence using carbon disulphide. We have studied the cyclodehydration step using acetic anhydride, trifluoroacetic anhydride and 1,3-dicyclohexylcarbodiimide (DCC) at temperatures not exceding 60oC. Trifluroacetic anhydride proved to be the best reagent, giving a better yield and more easily purified products, although yields were also acceptable with the other two reagents.
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