A new acetylation procedure has been applied to 13 aryl-methyl ethers using boron chemistry. In this procedure, demethylation of aryl-methyl ethers and acetylation of the resulting phenols were combined into one procedure in order to shorten the number of stages and to achieve easy purification. Eleven known with/without bromine and two new [bis(3,4-diacetoxyphenyl)methanone and 5,5'-methylenebis(1,2-diacetoxy-3,4-dibromobenzene) (a natural bromophenol's acetylated derivative)] acetylated arene compounds were synthesised from their methoxy derivatives by this method. The effectiveness of the method was illustrated by producing an acetylated natural bromophenol from its methyl ether. The phenol form was obtained by hydrolysing the acetylated natural bromophenol. Thus, the advantage of this method in the natural product chemistry of phenolic compounds was confirmed.