A range of double unsaturated amides (,, and), obtained by cross-coupling reactions was reacted with aldehydes to hemiaminals. Heating the hemiaminals in the presence of Ac2O and pyridine affected clean conversion to the corresponding enamides, such as,, and. Alternatively, N, S-acetals were prepared which were oxidized to the sulfones. Treatment with base also gave the enamides, favoring the cis-isomer. However, this method is less ...
