Repeated Use of the Catalyst in Ln(OTf)3-Catalyzed Aldol and Allylation Reactions

The lanthanoide trifluoromethanesulfonate (lanthanoid triflate)-catalyzed aldol reactions of silyl enol ethers with aldehydes and allylation reactions of tetraallyltin with aldehydes proceeded smoothly in a water–ethanol–toluene system. The reactions proceeded much faster in the above solvent than in water–tetrahydrofuran. Repeated use of the catalyst in these reactions was realized by a very simple procedure.