Highly Regioselective Allylation of α-Enones and Epoxides with Lithium Tetraallyllanthanoid Ate Complex

Tetraallyllanthanoid ate complex (1), which was readily prepared in situ from tetraallyltin, lanthanoid trichloride, and butyllithium in tetrahydrofuran (THF), reacts smoothly with α-enones (3–11) with a high degree of 1,2-regioselectivity (1,2 : 1,4 = >99 : 1) to give 1,5-diene-3-ols in good to excellent yields. The mechanistic study with 4,4-(ethylenedioxy)-2,6-dimethyl-2,5-cyclohexadienone (29) as a probe suggests that single electron transfer (SET) may be involved in this carbonyl allylation reaction with 1. Allylative ring opening of styrene oxide with 1 occurs at the more subsituted carbon (α-attack) in higher selectivity (α : β = 85 : 15) than with allyllithium and allylmagnesium bromide in diethyl ether. The complex 1 reacts with 3,4-epoxy-1-butene (35) in diethyl ether predominantly at the most substituted carbon of the oxirane to give 3-hydroxymethyl-1,5-hexadiene (36) together with 1,6-heptadien-3-ol (37), (E) and (Z)-2,6-heptadienols (38) (36 : 37 : 38 = 87 : 9 : 4)