PEG6k-Catalyzed Green Synthesis of Mono- and Dispirocyclopropanes

A sustainable one-pot method was developed for synthesizing mono- and dispirocyclopropanes using biodegradable PEG6k in water at room temperature. N,N′-Dimethylbarbituric acid, aromatic aldehydes, and 2-(phenylsulfonyl)acetonitrile gave monospirocyclopropanes 4a–i, while pyrazolone derivatives afforded dispirocyclopropanes 6a–f. Single-crystal X-ray diffraction confirmed selected structures, while density functional theory revealed the electronic and charge-transfer characteristics of the molecules. The developed protocol provides a simple and efficient route with a low E-factor (0.73–0.92) and a more sustainable choice in line with green chemistry principles.