Synthesis, characterization and catalytic properties of chiral BINOL functionalized mesoporous silicas for enantioselective Morita-Baylis-Hillman reaction

Several Chiral BINOL functionalized mesoporous silicas were prepared by post grafting of organosilane derivatives of (S)-BINOL (1,1'-bi-2-naphthol) on SBA-15 and characterized by C-13 CP/MAS NMR, FT-IR, UV-visible absorption spectra, elemental analysis, powder XRD, nitrogen adsorption-desorption isotherms and TEM techniques. Their catalytic properties were demonstrated in enantioselective Morita-Baylis-Hillman reaction of 3-phenylpropanal and cyclohexenone. Among them, 3BSBA-15 linked through the 3 position of BINOL exhibit higher enantioselectivity (26% e.e.) and yield (88%) which are similar to the homogeneous catalyst (S)-BINOL (27% e.e. and 92% yield) as Bronsted acids catalyst, while complex of 3BSBA-15 and calcium 3BSBA-15-Ca show lower enantioselectivity (21% e.e.) than its homogeneous complex (S)-BINOL-Ca (32% e.e.) as ligand catalyst. 3BSBA-15 and 3BSBA-15-Ca can be reused with no significant decrease in enantioselectivity and yield.