3-Fluorotetrahydropyran-4-one derivatives from homopropargyl acetal

A gold(I)-catalysed regioselective method for the preparation of 3-fluoro-tetrahydropyran-4-one derivatives from homopropargyl acetal is reported. A one-pot procedure based on a gold(I)-catalysed Petasis–Ferrier rearrangement/cyclization and subsequent fluorination was developed. The 3-fluoro-pyran-4-one compound acts as a protected precursor of alkylfluoro-α,β-(E)-unsaturated ketone, which was readily obtained by ring-cleavage. Corresponding hemiacetals were not suitable substrates for the formation of the 3-halo-pyran derivatives. The present transformation would represent a useful method to readily afford highly substituted 3-fluoro-tetrahydropyran-4-ones.