Carbene-Mediated Transformations of 1-(Benzylideneamino)benzimidazoles

Abstract

Carbene-mediated transformations of N-(3-butylbenzimidazol-3-ium-1-yl)-1-arylmethanimine iodides with carbon disulfide and benzoyl isothiocyanate gave the corresponding NHC·CS2 betaines in 68−85% and benzoyl-[1-butyl-3-[(E)-(aryl)methyleneamino]benzimidazol-1-ium-2-carbothioyl]azanides, respectively, in 74−85% yields. However, reaction with excess isopropyl isothiocyanate in NaH/THF at room temperature yielded the 1-butyl-1′,3′-diisopropyl-3-[(E)-(aryl)methyleneamino]spiro[benzimidazole-2,5′-imidazolidine]-2′,4′-dithiones (74−77%).