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
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This note was uploaded on 02/27/2010 for the course CHEM 140 taught by Professor Wade during the Spring '10 term at Whitman.