Double Nucleophilic Addition of Ketene Silyl Acetals to α,β-Unsaturated Imines: Factors Controlling the Regioselectivity

The regioselectivity of the double nucleophilic addition of ketene silyl acetals to α,β-unsaturated imines was highly depended on the subtle difference of the reactivity of the ketene silyl acetals, and the factors were mainly derived from the ability of the ketene silyl acetals to undergo the silicon-aluminum exchange reaction, where the aluminum enolate preferentially underwent 1,4-addition.