Do More Electrophilic Aldehydes/Ketones Exhibit Higher Reactivity toward Nucleophiles in the Presence of Lewis Acids?

A crucial role in the chemoselective synthesis of primary, secondary, and homoallylic alcohols and of Diels-Alder adducts is played by Lewis acids (LA) in the addition of nucleophiles (Nu) to carbonyl compounds (see scheme; EWG = electron-withdrawing group, EDG = electron-donating group).