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

Abstract

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.