Synthesis of Novel Structurally Diverse N-Mono- and N,N′-Disubstituted Benzimidazol-2-one Derivatives by the Alkylations of 1,3-Dihydro-2H-benzimidazol-2-one with Some Alkyl Halides under Transfer Catalysis Conditions

A series of N-mono- and N,N′-disubstituted benzimidazol-2-one derivatives optionally substituted on both secondary amine functionalities were prepared with excellent yields by reacting 1,3-dihydro-2H-benzimidazol-2-one in one and two steps respectively with various alkyl halides under phase transfer catalytic conditions. One of the synthesized N,N-disubstituted benzimidazol-2-one derivatives underwent a regiospecific 1,3-dipolar cycloaddition reaction at its side allyl substituent with the in situ generated 4-chloro benzonitrile N-oxide from 4-chlorobenzaldoxime to afford in good yield the corresponding N,N′-disubstituted derivative incorporating the 2,5-dihydro-isoxazole nucleus in one of the side chain. All the new compounds were fully characterized by their physical and spectroscopic data.