Publication Details (including relevant citation information):
Calatayud, D G, Escolar, F J, Lopez-Torres, E, Mendiola, M A Helvetica Chimica Acta 2007 90 (11) 2201-2216
Abstract: A selective synthesis of 4-methylthiosemicarbazide (=N-methylhydrazinecarbothioamide; 4a) derivatives by reaction with benzil (=1,2-diphenylethane-1,2-dione; 3) is described. The reaction conditions determined the condensation product formed. The most important factor was the acid used: in the presence of conc. HCl solution, the open-chain 2 : 1 compound 1a was exclusively obtained, whereas in the presence of 2M HCl, the cyclic 1 : 1 condensation product 2a was formed. The alcohol used, the presence of H2O, and the time of heating were additional crucial factors. The new cyclic compound 2a with a MeO group was exclusively formed when working under high-dilution conditions. The reaction with the 4-phenyl derivative 4b gave new cyclic compounds as the major products under all conditions used (Scheme).
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