Bis- and Azabis(oxazoline)–Copper–Tungstophosphate Immobilized on mesoporous silica: preparation and use as catalyst in enantioselective cyclopropanation

Mansilla, Daniela S. ; Pizzio, Luis R. ; Mayoral, José A. (Universidad de Zaragoza) ; Fraile, José M. ; Torviso, M. Rosario

Resumen: Tungstophosphoric acid (TPA) has been supported on mesoporous silicas prepared using urea as the pore forming agent. The amount of urea (20, 30, or 40% w/w) influences the silica specific surface area (SBET), total pore volume (Vp), and average pore diameter (Dp). The materials synthetized using 20% w/w (SiU20) display mainly mesoporous structures, with the highest Vp and Dp values being chosen to be used as TPA support. The SiU20-TPA solids with different TPA loadings (10, 20, or 30% w/w) have been used as supports for chiral copper catalysts with bis(oxazoline) or azabis(oxazoline) ligands. The catalytic efficiency of enantioselective cyclopropanation strongly depends on support morphology and TPA loading. SiU-TPA20 has been shown to be the optimal one. The stability of the complex is also a very important parameter, and the best results are obtained with an excess of chiral ligand to ensure the correct formation of the complex on the solid. In this way, with azabox-Cu/SiU20-TPA20 it is possible to obtain a highly selective (90% ee for the trans-cyclopropanes) and recoverable catalyst.

Idioma: Inglés

DOI: 10.3390/reactions6040059

Año: 2025

Publicado en: Reactions (Basel) 6, 4 (2025), 59 [13 pp.]
ISSN: 2624-781X

Financiación: info:eu-repo/grantAgreement/ES/DGA/E07-23R
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PID2021-125762NB-I00

Tipo y forma: Article (Published version)

Área (Departamento): Área Química Orgánica (Dpto. Química Orgánica)