Regioselective synthesis of n-formohydrazide and formyl pyrazole analogs as potent antimicrobial agents

A series of new (E)-N-(aryl)-N'-(1-(thiophen-2-yl)ethylidene)formohydrazides 2(a-g) and 1-(aryl)-3-(thiophen-2-yl)- 1H-pyrazole-4-carbaldehyde, 3(a-g) were prepared by the controlled Vilsmeier-Haack reaction. The reaction of (E)-1-aryl-2-(1-thiophen-2-yl)ethylidenehydrazines 1(a-g) with Vilsmeier-Haack reagent under different reaction conditions afforded the compounds 2(a-g) and 3(a-g) in good yield. The synthesized compounds were characterized by IR, 1H NMR, 13C NMR, Mass spectral, x-ray diffraction studies and elemental analysis. The compounds were screened for their antimicrobial susceptibility against different bacterium and fungi specie