Mild, fast, and stereoselective epoxide opening by ketone enolate anions. Application to synthesis of the norlignan curculigine.

We report here that (1) enolate anions of five- to seven-membered cycloalkanones nucleophilically open cyclopentene and cyclohexene oxides in 57-76% yields and with 4-8:1 diastereoselectivity; (2) enolate anions formed regiospecifically via kinetic deprotonation of 2-cyclohexenone and 2-cycloheptenone open cyclohexene oxide in 60-62% yields and with 32-95:1 diastereoselectivity; and (3) an aryl methyl ketone enolate anion opens a monosubstituted epoxide as the key step in a short synthesis of the gamma-hydroxyketone (GHK) aglycon of the natural product curculigine.