Synthesis of Novel Nitroimidazole‐Pyrazole Hybrids via an Attractive Methodology of N‐Alkylation of 4(5)‐Nitro‐1H‐imidazole

ABSTRACT

Imidazole is one of the most important heterocyclic rings. This nucleus can be found in a plethora of substances in different knowledge areas such as medicinal, agrochemical, polymer, and dyestuff. N‐alkylation reactions involving N − 1 atom is a remarkable tool to synthesize many imidazole derivatives which can be attached to a great variety of functional groups. In this work, we synthesized 10 new intermediates 4‐chlorobutyl 1‐aryl‐1H‐pyrazole‐4‐carboxylates 3(a–j) from 1‐aryl‐1H‐pyrazole‐4‐carbonyl chlorides, obtained from 1‐aryl‐1H‐pyrazole‐4‐carboxylic acids 4(a–j), and 4‐chlorobutan‐1‐ol 1, generated by THF ring‐opening promoted by hydrochloric acid. Compounds 3(a–j) promoted N‐alkylation of 4(5)‐nitro‐1H‐imidazole to afford the targets 4‐(4‐nitro‐1H‐imidazol‐1‐yl)butyl 1‐aryl‐1H‐pyrazole‐4‐carboxylates 2(a–j) in 18%–85% yields.