Synergistic Catalysis by Brønsted Acid/Carbodicarbene Mimicking Frustrated Lewis Pair‐Like Reactivity

• Published in: Angewandte Chemie International Edition 2021-09, Vol.60 (36), p.19949-19956
• Main Authors: Chan, Yi‐Chen, Bai, Yuna, Chen, Wen‐Ching, Chen, Hsing‐Yin, Li, Chen‐Yu, Wu, Ying‐Yann, Tseng, Mei‐Chun, Yap, Glenn P. A., Zhao, Lili, Chen, Hsuan‐Ying, Ong, Tiow‐Gan
• Format: Article
• Language: English
• Subjects: Basicity; Benzyl alcohol; BnOH; carbodicarbene; Catalysis; Catalysts; frustrated Lewis pair; Isocyanates; Mimicry; Polymethyl methacrylate; Reactivity
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202107127

Carbodicarbene (CDC), unique carbenic entities bearing two lone pairs of electrons are well‐known for their strong Lewis basicity. We demonstrate herein, upon introducing a weak Brønsted acid benzyl alcohol (BnOH) as a co‐modulator, CDC is remolded into a Frustrated Lewis Pair (FLP)‐like reactivity. DFT calculation and experimental evidence show BnOH loosely interacting with the binding pocket of CDC via H‐bonding and π‐π stacking. Four distinct reactions in nature were deployed to demonstrate the viability of proof‐of‐concept as synergistic FLP/Modulator (CDC/BnOH), demonstrating enhanced catalytic reactivity in cyclotrimerization of isocyanate, polymerization process for L‐lactide (LA), methyl methacrylate (MMA) and dehydrosilylation of alcohols. Importantly, the catalytic reactivity of carbodicarbene is uniquely distinct from conventional NHC which relies on only single chemical feature of nucleophilicity. This finding also provides a new spin in diversifying FLP reactivity with co‐modulator or co‐catalyst. In the presence of co‐modulator alcohol, the putative strong σ donor, CDC is reshaped into frustrated Lewis pair‐like reactivity. The unique synergistic FLP behavior of CDC; unachievable by its counterpart NHCs, is shown to have beneficial and complementary effects on isocyanate cyclotrimerization, LA polymerization, MMA polymerization and dehydrosilylation of alcohols.