The tetrahydrofolate coenzymes are involved in the biochemical transfer of a one-carbon fragment at dif-ferent oxidation levels. When the one-carbon unit is at the formic oxidation level, the imidazoline with a five-membered ring structure is the active site. In this paper, three benzimidazolium salts were respectively used as a tetrahydrofolate coenzyme model at formic acid oxidation level and methyl magnesium iodide as a nucleophile to which one-carbon unit was transferred. Thus the biomimetic synthesis of three important methyl ketone perfumes, methyl hexyl ketone, methyl nonyl ketone, and methyl undecyl ketone was successfully accomplished by using the addition-hydrolysis reaction of the corresponding benzimidazolium salts with methyl magnesium iodide. Their structures were characterized by elemental analysis, 1H NMR, IR and MS techniques. The reaction mechanism and the effects of reaction conditions on the yield were investigated. A novel convenient method for biomimetic synthesis of methyl ketone perfumes from carboxylic acids has been thus provided.

Key words: methyl ketone perfume, biomimetic synthesis, benzimidazole methiodide salt, Grignard reagent, tetrahydrofolate coenzyme