ACETALIZATION OF KETONES AND ALDEHYDES CATALYZED BY LANTHANOID TRISULFONATES

Lanthanoid sulfonates are found to be good catalysts for the acetaliza tion of aldehydes and ketones with methyl orthoformate in methanol. Th e catalytic activity of Ln(OTf)(3) (OTf, trifluoromethane-sulfonate) i ncreases in the order of La< Sm < Gd < Er < Yb. As sulfonates such as trifluoromethylsulfonates and (1s)-10- camphorsulfonates are more solu ble in organic solvents than the chlorides, the acetalization in ether or dichloromethane and the exchange reaction of alkoxy groups between acetals and alcohols can be achieved under mild conditions.