Daratu E. K. Putri, Katsumasa Sakoda, Yoshiki Takamoto, Sho Yamaguchi, Takato Mitsudome, Tomoo Mizugaki
Upcycling aliphatic polyesters into nitrogen-containing heterocycles offers an emerging route to valuable chemicals from plastic waste. Herein, we report the first demonstration of direct transformation of poly(ε-caprolactone) (PCL) into azepane (AZP), a bioactive seven-membered N-heterocycle relevant to pharmaceutical synthesis. A titanium oxide-supported platinum catalyst (Pt/TiO2) efficiently promotes the transformation, affording AZP in 75% yield, and exhibits robust reusability. Spectroscopic analyses and control experiments reveal that TiO2 facilitates the initial depolymerization of PCL via vacancy-associated Lewis acid sites, while electron-rich Pt nanoparticles (NPs) promote H2 dissociation. The synergistic interplay between Pt and TiO2 enables the sequential depolymerization and hydrogenation of PCL, leading to the highly selective formation of AZP. This catalytic platform provides a practical and reusable route for plastic valorization, enabling sustainable access to bioactive nitrogen heterocycles from polymeric feedstocks. This journal is © The Royal Society of Chemistry, 2026.
Department of Materials Engineering Science, Graduate School of Engineering Science, The University of Osaka, 1-3 Machikaneyama, Osaka, Toyonaka, 560-8531, Japan; Departemen Kimia, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Negeri Malang, Jl. Semarang 5, Malang, Lowokwaru, 65145, Indonesia; Graduate School of Engineering, Kobe University, Hyogo 657-8501, Kobe, Japan; Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), The University of Osaka, Osaka 565-0871, Suita, Japan; Research Center for Solar Energy Chemistry, Graduate School of Engineering Science, The University of Osaka, 1-3 Machikaneyama, Osaka, Toyonaka, 560-8531, Japan
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