Pentadienyl transfer reagents based on zirconium: preparation and reactions with carbonyl compounds

A variety of 2,4-pentadienylzirconiums were generated by reacting pentadienyl ethers with zirconocene ‘Cp2Zr’. These complexes underwent a highly γ-regioselective and anti-stereoselective in situ addition with carbonyl compounds to afford bis(homoallylic) alcohols in good yields. The reversal of anti vs syn selectivity was simply achieved with BF3, thus expanding the synthetic potential of the reaction.