Pentafluorophenylammonium trifluoromethanesulfonimide (C 6 F 5 N + H 3 ·NTf 2 À ) promotes Mukaiyama aldol and Mannich reactions using ketene silyl acetals with ketones and oxime ethers, respectively. The present robust method is mild, but powerful enough to utilize less accessible electrophiles such as enolizable ketones and oxime ethers to produce a variety of b-hydroxy esters and b-alk-

The NaOH-catalyzed first sequential Mukaiyama-Michael reaction/crossed-Claisen condensation is developed using two molar ketene silyl acetals and one molar alpha,beta-unsaturated esters in either a stepwise or one-pot manner.

The catalyst allows facile access to β‐hydroxy esters, β‐amino esters, and 5‐oxo esters.

A sequential Mukaiyama—Michael reaction and regioselective crossed‐Claisen condensation to afford 1,3,7‐tricarbonyl scaffolds is developed using two equivalents of ketene silyl acetals (II)/(IV) and one equivalent α,β‐unsaturated esters (I) in either a stepwise or one‐pot procedure.