Catalytic Asymmetric Allylation of Ketones and a Tandem Asymmetric Allylation/Diastereoselective Epoxidation of Cyclic Enones

A simple procedure is reported for the catalytic asymmetric allylation of ketones, utilizing titanium tetraisopropoxide, BINOL, 2-propanol additive, and tetraallylstannane as allylating agent. A variety of ketone substrates, including acetophenone derivatives and alpha,beta-unsaturated cyclic enones, reacted to form tertiary homoallylic alcohols in good yields (67-99%) and with high levels of enantioselectivity (generally >80%). A novel one-pot enantioselective allylation/diastereoselective epoxidation has also been introduced. Thus, upon completion of the allyl addition to conjugated cyclic enones, 1 equiv of tert-butyl hydroperoxide is added and the directed epoxidation of the allylic double bond ensues to afford the epoxy alcohol with high diastereoselectivity.