Three protocols have been developed for achieving ordered, multiple (serial) Michael reactions initiated by silyl enol ethers or silyl ketene acetals. Anion (fluoride or m- chlorobenzoate) catalysis was most effective for reactions of silyl ketene acetal 2 with bis diesters, aa in the highly selective formation of 3. Lewis acid (ZnIz) catalysis was more general than anion catalysis and afforded stereochemically complementary products with ...
