Prins cyclization of (-)-isopulegol with benzaldehyde for production of chromenols over organosulfonic clays

A1 Originalartikel i en vetenskaplig tidskrift (referentgranskad)


Interna författare/redaktörer


Publikationens författare: Nikolai Li-Zhulanov, Päivi Mäki-Arvela, Mathias Laluc, Andreia F. Peixoto, Ekaterina Kholkina, Thomas Sandberg, Atte Aho, Konstantin Volcho, Nariman Salakhutdinov, Cristina Freire, Alexander Yu. Sidorenko, Dmitry Yu. Murzin
Förläggare: Elsevier
Publiceringsår: 2019
Tidskrift: Molecular Catalysis
Tidskriftsakronym: Mol. Catal.
Volym: 478
Antal sidor: 12
ISSN: 2468-8231
eISSN: 2468-8231


Abstrakt

Prins cyclization of (-)-isopulegol with benzaldehyde was investigated with sulphur containing halloysite nanotubes, K10 clays and Cloisite clays. The catalysts were characterized by TEM, SEM, XRD, XPS, pyridine adsorption desorption by FTIR, nitrogen adsorption. The most active catalyst was K10 modified with chlorosulphonic acid giving 95% selectivity to the desired chromenol at 90% conversion and 30 degrees C. Selectivity to chromenol was increasing with increasing Lewis acid site concentration while no linear correlation of chromenol selectivity with the Bronsted acid sites concentration was observed. The diastereoisomer R/S ratio of chromenols was the highest, 11.5, at 70 degrees C and 90% conversion over sulphur modified halloysite nanotubes exhibiting rather low acidity. A higher stability of the R-isomer confirmed by quantum mechanical calculations can partially explain preferential formation of the R diastereomer.Successful catalyst reuse was demonstrated with the best performing catalyst, organosilylated sulphur containing K10.


Nyckelord

Chromenols, Isopulegol, Organosulfonic clays, Prins reaction

Senast uppdaterad 2020-27-05 vid 04:33