Unveiling the synthesis and spectral characterizations of novel (E)-furan-2-yl acrylohydrazides: an exploration in molecular design

In this study, we present the synthesis of novel derivatives of 3-furan-2-yl acrylohydrazide using a meticulous three-step reaction sequence. The synthesis ends up in the condensation of (E)-3-(furan-2-yl) acrylohydrazide ( 3 ) with diverse benzaldehyde and acetophenone derivatives. Comprehensive characterization of the synthesized compounds was achieved through 1D nuclear magnetic resonance spectroscopic analyses ( 1 H and 13 C NMR), 2D nuclear magnetic resonance spectroscopy (HSQC, NOESY), and high-resolution mass spectrometry (HRMS). The investigation of 1 H NMR data at room temperature in deuterated dimethyl sulfoxide (DMSO- d 6 ) unveiled the existence of ( E )-3-(furan-2-yl) acrylohydrazide derivatives ( 4a–h ) in a conformational equilibrium, manifesting as a mixture of syn periplanar E (sp E ) and anti periplanar E (ap E ), Notably, compounds 4a and 4b predominantly adopted the sp E conformer ( E c=c sp E C=N ), while the remaining compounds ( 4c–h ), favored the antiperiplanar conformation ( E c=c ap E C=N ) even if for the 4g compound it was challenging to determine the E C=N conformer. These findings contribute valuable insights into the conformational dynamics of this class of compounds, holding significance for applications in diverse scientific domains.