David G. Calatayud - Facile and selective synthesis of 4-methyl- and 4-phenylthiosemicarbazide (= N-methyl- and N-phenylhydrazinecarbothioamide) derivatives of benzil (=1,2-diphenylethane-1,2-dione)

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  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).

  Address (URL): ISI:000251301900015