Chitosan–Cu Catalyzed Novel Ferrocenated Spiropyrrolidines: Green Synthesis, Single Crystal X-ray Diffraction, Hirshfeld Surface and Antibacterial Studies

Chitosan-bounded copper (chitosan-Cu) was introduced for green synthesis of novel ferrocenated spiropyrrolidine hybrids, namely 3'-(4-.bromobenzoyl)-5'-(4-hydroxybenzyl)-4'-ferrocenylspiro[indoline-3,2'-pyrrolidin]-2-one and 3'-(4-bromobenzoyl)-4'-ferrocenylspiro[indoline-3,2'-pyrrolidin]-2-one, in good yield. A one-pot three-component 1,3-dipolar cycloaddition reaction was employed for the formation of spiropyrrolidines from 1-(4-bromophenyl)-ferrocene-prop-2-en-1-one and azomethine ylides, which were developed in situ from tyrosine, glycine, and isatin, respectively. Various spectroscopic methods were used to establish the structures of spiropyrrolidines, and a single crystal X-ray diffraction study of a spiropyrrolidine provided additional confirmation. The crystallographic study revealed that compound <b>3a</b> has one independent molecule in its unit cell, which is correlated with Hirshfeld surface analysis, and describes intramolecular contacts adversely. The highly yielded products in green conditions were determined for their antibacterial significance and were found to have good activity against Gram-positive and Gram-negative bacterial strains.