Zinc tetrafluoroborate catalyzed Mannich-type reaction of aldimines and silyl enol ethers in aqueous medium

The use of zinc tetrafluoroborate as a catalyst in Mannich-type addition of silyl enol ethers to aldimines in aqueous THF provides β-amino ketones or β-amino esters in high yields. A one-pot reaction of an aldehyde, amine and silyl enolate also works well.