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Highly Recyclable Fluoride for Enhanced Cascade Hydrosilylation–Cyclization of Levulinates to γ‑Valerolactone at Low Temperatures

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journal contribution
posted on 25.09.2017 by Wenfeng Zhao, Tingting Yang, Hu Li, Weibo Wu, Zhongwei Wang, Chengjiang Fang, Shunmugavel Saravanamurugan, Song Yang
A facile and benign catalytic route has been developed to quantitatively yield γ-valerolactone (GVL; ca. 97%) from biomass-based levulinates at room temperature to 80 °C by using easily available polymethylhydrosiloxane (PMHS) and KF as the liquid H-donor and recyclable catalyst, respectively. No extra step was required to liberate GVL from the in situ-formed siloxane, and this catalytic system exhibited a lower activation energy (40.9 kJ/mol) compared to previously reported ones. The deuterium-labeled study further demonstrated the reaction proceeding through cascade hydrosilylation and cyclization with fluoride successively acting as the nucleophile and base. In addition, the PMHS-derived resin was extremely favorable to restrain the leaching of fluoride and maintain its constant activity for at least six cycles.