Synthesis of 1,3-diazaspiro[5,5]undecanes and 1-thia-3-azaspiro[5,5]undec-2-enes by reaction of 2-cyanocyclohexylideneacetyl isothiocyanate with amines and sodium hydrogen sulfide

Abstract

2-Cyanocyclohexylideneacetyl isothiocyanate (II) reacts with sodium hydrogen sulfide to give 1-thia-3-azaspiro[5,5]undecane. Reaction of II with secondary amines afforded 1-thia-3-azaspiro[5,5]undec-2-enes whereas primary aromatic amines gave 1,3-diazaspiro[5,5]undecanes under the same conditions. Both types of reactions proceed via substituted thioureas which were isolated pure only in the case of 4-methylaniline and 4-methoxyaniline. They were cyclized in alkaline medium to the corresponding diazaspiro derivatives. The structure of the synthesized compounds was confirmed by their elemental analyses and IR, 1H NMR, 13C NMR and mass spectroscopy.