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.
Posner
Gary H
GH
Department of Chemistry, School of Arts and Sciences, The Johns Hopkins University, Baltimore, MD 21218, USA. ghp@jhu.edu
Maxwell
John P
JP
Kahraman
Mehmet
M
D002384:Catalysis; D002625:Chemistry, Organic / Q000379:methods; D004852:Epoxy Compounds / Q000737:chemistry*; D007202:Indicators and Reagents; D007659:Ketones / Q000737:chemistry*; D007700:Kinetics; D017705:Lignans / Q000032:analysis / Q000138:chemical synthesis*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D013237:Stereoisomerism
D004852:Epoxy Compounds; D007202:Indicators and Reagents; D007659:Ketones; D017705:Lignans