Trans ition States Further Transformations TBAF or Occus with re entin f cefic steps Tamao oxidation: Organometallics 1983, 2, 1694 Meli R=Me, 75% over 2 steps Occurs with retention of co Stereoselectivity and Regioselectivity 80% 60: 40 mixture of isomers 1 isomer SiMex 160°c75% 2. TBAF-DMF 85% 2. TBAF-DMF 8 Stork, G: Chan, T.Y., Breault, G. A.J. Am. Chem. Soc. 1992, 114. 7578 33A-033/14965:30PMO H H Si R R H H O Si R R Si O R R OH OH OH OH SiMe3 O SiMe2 exo SiMe2 O endo Transition States: Me Me OH vs. Further Transformations: TBAF TBAF or KF then H2O2 MeLi R = Me or Ph, 71-85% over 2 steps Occurs with retention of configuration O Ph SiMe2 R = Me, 75% over 2 steps Ph OH Tamao oxidation: Organometallics 1983, 2, 1694. R = Me, 75% over 2 steps Occurs with retention of configuration 60:40 mixture of isomers 160 °C 80% TBAF-DMF, 75 °C 65% O SiMe2 Stereoselectivity and Regioselectivity: OH 1. 160 °C 75% 2. TBAF-DMF 85% 1. 180 °C 80% Ph 2. TBAF-DMF 85% Stork, G.; Chan, T. Y.; Breault, G. A. J. Am. Chem. Soc. 1992, 114, 7578. Ph 1 isomer 33A-03 3/14/96 5:30 PM