Sulfated zirconia (SO4/ZrO2) as a reusable solid acid catalyst for the Mannich-type reaction between ketene silyl acetals and aldimines

Sulfated zirconia (SO4/ZrO2) catalyzed Mannich-type reactions of ketene silyl acetals and aldimines proceeded smoothly at room temperature to afford β-amino esters in good to high yields. In addition, the heterogeneous solid acid catalyst SO4/ZrO2 was easily recovered from the reaction mixture and then reused without significant loss of effectiveness.