Ethanol promoted titanocene Lewis acid catalyzed synthesis of quinazoline derivatives

摘要

An efficient catalytic system involving in situ activation of kinetically inert titanocene dichloride with alcoholic solvent for the synthesis of quinazoline derivatives was developed. 1 mol% Cp2TiCl2 at 30 degrees C afforded 17 examples of quinazoline derivatives with yields of 95-98% in 7-12 minutes. Mechanistic experiments using in situ NMR and HRMS established that the coordination of ethanol to the titanocene moiety released the catalytic species [Cp2Ti(OCH2CH3)(2)].