π-Allyi lanthanoid ate complex as a new highly 1,2-regioselective allyl transfer agent for α,β-unsaturated carbonyl compounds

The π-allyi lanthanoid ate complex (1), which was prepared in situ from tetra-allyltin, the lanthanoid trichloride, and n-butyl-lithium in tetrahydrofuran (THF), reacts smoothly with α,β-unsaturated carbonyl compounds (3)–(11) with a high degree of 1,2-regioselectivity to give 3-hydroxy-1, 5-dienes (12)–(20) in good to excellent yields.