Preparations of spherical nanoparticles of chiral Cinchona alkaloid-based bridged silsesquioxanes and their use in heterogeneous catalysis of enantioselective reactions

0584832 - ÚCHP 2025 RIV GB eng J - Journal Article
Tetour, D. - Novotná, M. - Tatýrek, J. - Máková, V. - Stuchlík, M. - Hobbs, C. - Řezanka, M. - Müllerová, Monika - Setnička, V. - Dobšíková, K. - Hodačová, J.
Preparations of spherical nanoparticles of chiral Cinchona alkaloid-based bridged silsesquioxanes and their use in heterogeneous catalysis of enantioselective reactions.
Nanoscale. Roč. 16, č. 13 (2024), s. 6696-6707. ISSN 2040-3364. E-ISSN 2040-3372
Institutional support: RVO:67985858
Keywords : asymmetric dihydroxylation * mesoporous organosilica * polymer support * olefins
OECD category: Organic chemistry
Impact factor: 6.7, year: 2022
Method of publishing: Open access
https://pubs.rsc.org/en/content/articlepdf/2024/nr/d3nr06234a

Two spherical nanoparticulate materials were prepared by base-catalyzed sol-gel hydrolysis/self-condensation of the bis-Cinchona alkaloid-phthalazine-based bridged bis(triethoxysilanes). For the purpose of comparing the catalytic properties, two compact materials were also prepared from the same precursors using a fluoride-catalyzed sol-gel process. All materials were characterized by SEM, TEM, solid-state( 29)Si NMR and C-13 NMR, TGA, and FTIR. The prepared silsesquioxane-based materials were studied as potential heterogeneous catalysts for selected enantioselective reactions. The spherical material with regularly incorporated bis-quinine-phthalazine chiral units exhibited good to excellent enantioselectivities in osmium-catalyzed dihydroxylations of alkenes. Enantioselectivities observed in dihydroxylations of aromatic trans-alkenes were as excellent as those observed with the homogeneous catalyst (DHQ)(2)-PHAL. One compact and one nanoparticulate material was successfully recycled and reused five times without loss of enantioselectivity. Furthermore, both quinine-based and cinchonine-based materials were tested as heterogeneous organocatalysts for chlorolactonization of 4-arylpent-4-enoic acids. The materials showed only moderate enantioselectivities, however, these are the first heterogeneous catalysts for enantioselective chlorolactonization published so far.
Permanent Link: https://hdl.handle.net/11104/0352660