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Investigación contiene los documentos generados por los docentes e investigadores de la Universidad en su labor de investigación. Este depósito tiene como objetivos el almacenamiento, la gestión, la preservación y la difusión de estos documentos, y pretende contribuir al aumento de la visibilidad del trabajo desarrollado por los miembros de la comunidad universitaria.
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- PublicationOpen AccessCooperative fluoride binding in (thio)urea [2]rotaxanes: a mechanical-bond approach to phase‐transfer catalysis(2026-07-05) Puigcerver Alarcón, Julio; Zamora Gallego, José María; Marín Luna, Marta; Alajarín Cerón, Mateo; Martínez Cuezva, Alberto; Berná Cánovas, José; Química Orgánica; Facultades de la UMU::Facultad de QuímicaThe distinctive features of mechanically interlocked molecules have been widely recognised for decades.[1] In this context, our research focuses on integrating the unique structural characteristics of rotaxanes with the catalytic potential of specific functional motifs.[2][3] Hydrogen-bond donor groups such as ureas and thioureas have been extensively employed in anion sensing[4] and anion-binding catalysis.[5] Nevertheless, various strategies have been developed to address their intrinsic limitations and enhance their catalytic performance.[6] In this study, we explore the catalytic potential of tetraamide [2]rotaxanes incorporating urea and thiourea moieties as hydrogen-bonding phase-transfer catalysts in nucleophilic fluorination reactions.[7] We hypothesised that the hydrogen-bond-donating nature of the tetralactam macrocycle could strengthen the interaction of these functional groups with fluoride anions. To test this hypothesis, a series of urea-functionalised rotaxanes were designed and evaluated as catalysts. Our results demonstrate that the cooperative activation of fluoride between the macrocycle and the hydrogen-bond donor significantly improves reaction yields compared with non-interlocked thread analogues.[8] Furthermore, we report a clipping strategy employing activated isophthaloyl-derived esters as key precursors for the synthesis of thiourea-containing rotaxanes. This approach overcomes the incompatibility issues encountered when acyl chloride derivatives were used in the presence of highly nucleophilic thiourea groups. The steric constraints imposed by the mechanical bond enable the use of an interlocked thiourea as a hydrogen-bonding phase-transfer catalyst in nucleophilic fluorination, a reaction previously restricted to urea-based systems.[9] Overall, these findings highlight the pivotal role of the mechanical bond in modulating catalytic activity. References [1] C. J. Bruns, J. F. Stoddart. The Nature of the Mechanical Bond: From Molecules to Machines. Wiley, Weinheim, 2016. [2] A. Martinez-Cuezva, A. Saura-Sanmartin, J. Berna, M. Alajarin. ACS Catal. 2020, 10, 7719. [3] M. Calles, J. Puigcerver, D. A. Alonso, M. Alajarin, A. Martinez-Cuezva, J. Berna, Chem. Sci. 2020, 11, 3629. [4] S. Kundu, T. K. Egboluche, M. A. Hossain. Acc. Chem. Res. 2023, 56, 1320. [5] K. Brak, E. N. Jacobsen. Angew. Chem. Int. Ed. 2013, 52, 534. [6] T. J. Auvil, A. G. Schafer, A. E. Mattson. Eur. J. Org. Chem. 2014, 2633. [7] G. Pupo, V. Gouverneur. J. Am. Chem. Soc. 2022, 144, 5200. [8] J. Puigcerver, J. M. Zamora-Gallego, M. Marin-Luna, A. Martinez-Cuezva, J. Berna. J. Am. Chem. Soc. 2024, 146, 22887. [9] J. Puigcerver, J. S. Dato-Santiago, M. Alajarin, A. Martinez-Cuezva, J. Berna. Org. Lett. 2025, 27, 2873.