Work

Bis- and Azabis(oxazoline)–Copper–Tungstophosphate Immobilized on Mesoporous Silica: Preparation and Use as Catalyst in Enantioselective Cyclopropanation

Year: 2025

Type: article

Abstract: 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.

Source: Reactions

DOI: 10.3390/reactions6040059

Authors: Daniela S. Mansilla, Luis R. Pizzio, José A. Mayoral, José M. Fraile, M. Rosario Torviso

Institutions: Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires, Universidad Nacional de La Plata, Universidad de Zaragoza, Instituto de Síntesis Química y Catálisis Homogénea

Language: English

Topic: Cyclopropane Reaction Mechanisms

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,207

Funders: Gobierno de Aragón, Agencia Nacional de Promoción de la Investigación, el Desarrollo Tecnológico y la Innovación, Agencia Estatal de Investigación