Preparation of <i>N</i>-Alkylketene-<i>N</i>-Butadienyl-<i>N,O</i>-Silyl Acetals

The synthesis of a series of dienamides <b>5a-j</b> using Oppolzer’s method is described. Using Rathke’s method the ketene <i>N,O</i>-silyl acetals <b>6a-j</b> can be obtained in good yield from the corresponding dienamines. The ketene acetals are obtained free of base and free of salts. They are stable and can be stored at -20°C. The new dienes are useful reagents for tandem reactions.