Stereoselective synthesis, structural determination, computational studies and antimicrobial activity of novel class of spiropyrroloquinoxaline engrafted ferrocenoindole hybrid heterocycle

•Synthesis of a structurally unexplored novel class of ferrocene fused spiropyrrolidine hybrid.•Spiro compound was achieved in excellent yield via a one-pot multicomponent cascade protocol.•The synthesized compound was elucidated by spectroscopic, X-ray diffraction and computational studies.•Spirocompound displayed significant activity against tested MDR S. aureus strains. Our synthetic approach for the assembly of highly diversified spiropyrrolidine grafted ferrocene was based on a one-pot four component cascade reaction protocol involving 1,3-dipolar cycloaddition reaction of (E)-3-ferrocene-1-(4-bromophenyl)prop‑2-en-1-one and azomethine ylide generated in situ from quinoxalinone and l-tryptophan. The structure of the compound was assigned by one- and two-dimensional NMR spectroscopic studies. The regio- and stereochemistry of the spirocompound was confirmed by single crystal X-ray diffraction analysis. The nature of three-dimensional orientation of the synthesized compound has been investigated through single crystal X-ray diffraction study. Crystal structure of the synthesized compound was analyzed using Hirshfeld calculations. In spirocompound, the packing of molecules is controlled by significant O…H (3.3%), N…H (4.1%) and CH…π (24.8%) interactions. The different π-donation and π-back donation interactions was analysed using NBO calculations. The compound 6 exhibited potent inhibitory activity against tested MDR S. aureus strains ranging from 8.00 to 256.00 µg/mL with respect to MIC and MBC determination.