2,3-Dihydrobenzofuran derivatives, important intermediates of medicines and agricultural chemicals, were prepared from aryl methallyl ethers over MCM-41 mesoporous material catalysts. Two mesoporous materials with Si/Al mole ratios of 40 and 50 were prepared to investigate the effect of acid site concentration on their catalytic activities. Aryl methallyl ethers with various substituents on their benzene rings were used to investigate the effect of electron density on benzene ring on the conversion of the ethers and the yield of 2,3-dihydorbenzofuran derivatives. The catalyst with a high acid site concentration showed high conversions, but it is difficult to correlate the yield of the derivatives with the acid site concentration. The increase in the electron density of the benzene ring by introducing electron-donating groups accelerated Claisen rearrangement reaction, resulting in the enhanced yield of the derivatives. On the other hand, the decrease in the electron density by introducing electron-attracting groups accelerated the cracking reaction of aryl methallyl ether by acid catalysts, producing phenol derivatives rather than 2,3-dihydrobenzofuran derivatives.