Efficient preparation of binaphthol-derived active μ₃-oxo titanium catalyst by using hydrated Na-zeolites (molecular sieves)

NaA-zeolite (MS 4A), despite a desiccant of choice, serves anomalously as an H₂O donor for the titanium precatalyst and acts as a base to trap HCl to give our active binaphthol-derived titanium (BINOL-Ti) catalyst (1) for the glyoxylate-ene reaction. The active species of BINOL-Ti catalyst (1) is primarily composed of the μ₃-oxo (Ti₃O) species, for which the NaA-zeolite employed in the catalyst preparation acts as an H₂O donor. Among zeolites with a variety of counter-cations, Na-zeolites are found to enable the quick formation of the active BINOL-Ti catalyst. A sufficient amount of sodium cations in the zeolites is critical for the efficient preparation of the active catalyst rather than the sodium content, pore size, and acid/base character based on the aluminosilicate (zeolites) frameworks.