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Thermal Behavior of Some 2-(3-R-Thioureido)benzonitriles

P. Pazdera, J. Meindl, and E. Nováček

Department of Organic Chemistry, Faculty of Natural Sciences, Masaryk University, CS-611 37 Brno

Abstract: The behaviour of some 2-(3-R-thioureido)benzonitriles under heating without solvent at the temperature higher than their melting point or boiling in aqueous dimethylformamide was followed.It was found that primary and secondary alkyl or aryl derivatives afford by the cyclization reaction followed by a rearrangement 4-(R-amino)-2-thioxo-1,2-dihydroquinazolines.3-tert-Butyl derivative eliminates methylpropene and in the following cyclization 4-amino-2-thioxo-1,2-dihydroquinazoline is formed. 2-(3-Adamantylthioureido)benzonitrile under similar conditions decomposes to aminoadamantane and 2-isothiocyanatobenzonitrile.2-(3-R,3-R'-Thioureido)benzonitriles under similar conditions eliminate alkene and the following cyclization and rearrangement gives 4-(R-amino)-2-thioxo-1,2-dihydroquinazolines. Heating of 2-(3,3-dimethylthioureido)benzonitrile ends in the formation of carbene that in the dependence on conditions of the reaction either dimerizes or polymerizes.

Full paper in Portable Document Format: 465a322.pdf

Chemical Papers 46 (5) 322–328 (1992)