Cooperative catalysis with binary Lewis acid–Lewis base system for the coupling of carbon disulfide and epoxides

摘要

The cycloaddition of epoxides with carbon disulfide proceeds effectively by using a binary catalyst system of tetradentate Schiff-base aluminum complexes (designated as salenAlX) as Lewis acid in connection with a nucleophilic co-catalyst, such as quaternary ammonium salt. The steric factor of the substituent groups on the aromatic rings of salenAlX and the anion of quaternary ammonium salt all have significant effects on the activity of the binary catalyst system, as well as the selectivities of the resultant cyclic products. The effects of temperature, time and the molar ratio of reactants were also investigated in detail with regard to propylene oxide with carbon disulfide, and a plausible mechanism was proposed. Copyright ? 2012 John Wiley & Sons, Ltd.