Substitution of 4-Hetero-Substituted 2-Azetidinones with 1,2- and 1,3-Disilyl-2-butenes and Their Stereochemical Effects on 4-(1-Methyl-2-propenylation) - Kang, Jahyo; Kim, Jooin; Lee, Kee-Jung (Synlett, 1991)