Solvent-free and catalyst-free Clasien rearrangement of five kinds of allyl phenyl ethers were investigated under microwave heating and conventional heating respectively. The effects on the reaction rates by microwave heating and conventional heating were compared. The results demonstrate that microwave heating could greatly accelerate the reaction rate of the Claisen rearrangement. The reaction rates under microwave heating are 5～10 times higher than those acted by conventional heating at 190 ℃. The microwave heating is an efficient method of catalyst-free, high yield of Claisen rearrangement.

Key words: solve-free, catalyst-free, Claisen rearrangement, microwave assisted synthesis, allyl phenyl ether