Muscone is a precious fragrant compound scarce in nature. Many attempts have been made to synthesize this unique natural product. In this work, the one-carbon unit transfer reaction of tetrahydrofolate coenzyme was initiated. Benzimidazolium salt was used as the tetrahydrofolate coenzyme model at formic acid oxidation level and di-Grignard reagent as the nucleophile to which one-carbon unit was transferred; the biomimetic synthesis of 2,15-hexade-canedione, a precursor of muscone, was successfully accomplished by using the addition-hydrolysis reaction of benzimidazolium salt with Grignard reagent. And an important useful method for the synthesis of muscone is provided.