Synthesis of Novel Nitroimidazole‐Pyrazole Hybrids via an Attractive Methodology of <scp>N</scp>‐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‐1 H ‐pyrazole‐4‐carboxylates 3(a–j) from 1‐aryl‐1 H ‐pyrazole‐4‐carbonyl chlorides, obtained from 1‐aryl‐1 H ‐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‐1 H ‐imidazole to afford the targets 4‐(4‐nitro‐1 H ‐imidazol‐1‐yl)butyl 1‐aryl‐1 H ‐pyrazole‐4‐carboxylates 2(a–j) in 18%–85% yields.