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

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

Simposio; 18th European Symposium on Organic Chemistry; 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.[1] 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 (Scheme 1) requires short reaction time, 80 ºC temperature, and a catalytic amount of PCSiO2 or KCSiO2 in solvent free-conditions to deliver the required products in good to excellent yields, and as a unique diastereomer.