Title
Diving into the chiral pool: enantiopure microporous polysilsesquioxane spheres from both enantiomers with an oxazolidinone motif
Author
Malina Bilo, Michael Sartor, Hiba Nasser, Young Joo Lee, Felix J. Brieler, Michael Fröba
Year
2018
Journal
Journal of Sol-Gel Science and Technology
Abstract
Organosilica hybrid materials from bridged silsesquioxanes combine attractive properties of a silica backbone with flexible organic compounds. This class of materials is of interest for different applications. Enantiopure chiral polysilsesquioxanes play a role in fields like the enantioselective catalysis or chromatography. Different applications have been used for their synthesis already. Here, l-valine, representative of the chiral pool, and the respective enantiomer d-valine were used to design two enantiomers of oxazolidinone derivates in a multistep synthesis path. The oxazolidinones were bis-silylated in a double Heck cross-coupling. Formation of micropores was realized by self-assembly of the precursors under suitable conditions, leading to polysilsesquioxanes with high surface areas as could be investigated by argon physisorption. The materials were profoundly characterized using solid-state NMR. The retention of the stereogenic information could be proven by circular dichroism measurements of the precursors as well as the respective hybrid materials. Furthermore, the materials were obtained in spherical morphology.
Instrument
J-815
Keywords
Circular dichroism, Stereochemistry, Cotton effect, Materials