18-±4 Trimethylphosphine has A-hydrogens that could be removed by butylLithium, generating undesired yLides. CH3 1+ Bu±i 1+ -CH² ±+ CH3³P´CH2 R ± µ¶ ³P·C¸ + 3 1 CH ´P´CH R 2 µH² desired y¹ide wrONg ylide rotaºion . • : ² h PPh3 \ \ I" H '» ¼¼I H Me Me :½ ¾¿ PPh) / I C _ À» » Ph3P½ ±²³´ f-µ " , 1 I Me ÁÂ Ã Ä Åe HÆÇ r / ÈÉS-Ê-butene The stereochemistry is invertedË The nucleophile triphenylphosphine must attack the epoxÌde in an antÍ fashioN, yet the triphenylphosphine oxide must eliÎnÏte with syN geometryË
This is the end of the preview. Sign up
access the rest of the document.