Simple amidation of unprotected phenol-containing 2-alkenoic acids

A series of amides of 2-E-alkenoic acids have been synthesised through the activation of these acids with dicyclohexylcarbodiimide / pentafluorophenol and further reaction with amines under microwave irradiation. In daylight, the E-configured amides undergo a slow photochemical E/Z-isomerisation. Photoirradiation experiments with selected 3-(hydroxyphenyl)-2(E)-alkenamides were carried out using a high pressure mercury UV lamp.