Selective access to new semicarbazones and thiosemicarbazones derived from benzil. Study of their conversion reactions

Article abstract of DOI:10.1016/S0040-4020(98)00667-X

New Schiff bases from benzil with semicarbazide and thiosemicarbazide are reported. An open chain molecule, benzilbissemicarbazone 1 was prepared in presence of lithium hydroxide. A cycle 6-methoxy-1,6-diphenyl-4-thio- 3,4,5,6-tetrahydro-2,3,5-triazine 7 was obtained from thiosemicarbazide. A cyclic molecule, 1,6-diphenyl-4-oxo-3,4,5,6-tetrahydro-2,3,5-triazine 4 was produced from the recrystallization of 3 in chloroform. A new macrocyclic complex 8 was isolated from the open chain 6 in the presence of iron (III) chloride hexahydrated. Compounds 1, 2 convert into the cyclic 3 heated under reflux. In addition, we have got an iron complex 5 of 1 using the compound 2 as precursor. The crystal structure of 7 was obtained by single crystal X- Ray diffraction.