Abstract Reaction of 1, 3-dihalo-3-methy]-2-butanone with t-butyl acetoacetate (NaH) gave t- butyl 3, 4-dihydro-2, 2, 6-trimethyl-4-oxo-2H-pyran-5-carboxylate via the Favorskii-type rearrangement. Michael addition of 4-methylphenyllithium (CuI) followed by ring cleavage with Me 3 SiCl-NaI in DMF or PrCN afforded ar-atlantone as well as (±)-ar-turmerone selectively.