Binary conjugate Bronsted-Lewis acid supported on mesoporous silica nanoparticles for the domino addition/elimination/addition and addition/elimination/addition/cyclization cascade

Fluoroboric acid (HBF4) adsorbed on mesoporous silica nanoparticles of 25-30 nm dimension was synthesized and characterized by N-2 adsorption, HRTEM, EDX, XPS, XRD, Si-29 MAS NMR etc. The applicability of silica-HBF4 was probed through a library synthesis of tetraketones or their tautomeric enol forms. These tetraketones are further transformed into xanthenes. Synthesis using aqueous-ethanol is of paramount importance for its sustainable green impact. (C) 2013 Elsevier B.V. All rights reserved.