Preyssler and Keggin heteropolyacids encapsulated in a silica framework for the preparation of fluorinated hexahydropyridines

V. PALERMO; A. SATHICQ; D. RUIZ; T. CONSTANTIEUX; J. RODRIGUEZ; P. VÁZQUEZ; G. ROMANELLI

Marsella

Conferencia; ESOC-2013; 2013

Heterogeneous catalysts have gained much importance in recent years due to sustainable and economic considerations. Their use in multicomponent reactions reinforces the environmental benefits of these sequences. In this context, trifluoromethylated hexahydropyrimidines were synthesized in solvent-free conditions, using commercial Keggin (H3PMo12O40, KC) or Preyssler (H14NaP5W29MoO110, PC),2 heteropolyacids encapsulated in a silica framework as heterogeneous catalysts. The encapsulated catalysts (PCSiO2 and KCSiO2) were prepared by the sol-gel technique using tetraethyl orthosilicate as precursor.2,3 This trifluoromethylated hexahydropyrimidine synthesis requires short reaction time, 80 ºC temperature, and a catalytic amount of PCSiO2 or KCSiO2 in solvent freeconditions to deliver the required products in good to excellent yields, and as a unique diastereomer.