Efficient synthesis of 5-bromo-2,3-dimethoxy-6-methyl-1,4-benzoquinone: key intermediate for preparing Coenzyme Q

The title compound, a key intermediate for preparing Coenzyme Qn family, was prepared in an excellent yield by a reaction sequence starting from the commercially available 3,4,5-trimethoxytoluene 1 via bromination, methoxylation and oxidation reactions. An 80% overall yield was demonstrated on a multi-gram scale.