| Chan Rearrangement |
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| CATEGORIES ABOUT CHAN REARRANGEMENT | |
| carbon-carbon bond forming reactions | |
| rearrangement reactions | |
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The Methylene group in the reactant with adjacent Carbonyl and Acetyl Substituent s is acidic and can be Deprotonated by strong non-nucleophilic bases such as Lithium Tetramethylpiperidide or Lithium Diisopropylamide as in an Aldol Reaction . The thus formed Enolate then gives a Nucleophilic Acyl Substitution with the adjacent Carbonyl of the acetyl group through a short lived intermediate Oxirane . Acidic workup liberates the free hydroxyl group. In a sample reaction Benzoic Acid (R' = phenyl) reacts with ethyl bromoacetate (R = ethoxy) and Anhydrous Potassium Carbonate in Reflux ing Acetone to the corresponding ester. Reaction with LDA in THF at 0°C results in the rearranged hydroxy-keto-ester with yields of 50 - 60%. This procedure was rediscovered and employed in the Holton Taxol Total Synthesis . SEE ALSO
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