Sulfate Zirconia for Mannich Reaction

Significance

The Mannich-type reaction of ald­imines with ketene silyl acetals was promoted by sulfated zirconia SO₄/ZrO₂ as a solid acid. Thus, the reaction of 1 with 2 was carried out with SO₄/ZrO₂ in MeCN to give β-amino esters 3 in 65-100% yield (eq. 1). The catalyst was recovered and reused with a slight loss of catalytic activity (yield of 3; 1^st use of SO₄/ZrO₂: 99%, 2^nd use: 99%, 3^rd use: 97%, 4^th use 90%).