Lecture Notes: Baeyer Villiger Oxidation

Introduction

• Presenter: Professor Dave
• Topic: Baeyer Villiger Oxidation
• Context: Previous tutorial covered Beckmann rearrangement

Overview

• Beckmann Rearrangement Review
  • Cyclic substrate: 6-membered ring ketone to a 7-membered lactam
  • Mechanism: Inserts nitrogen into C-C bond
  • Lactam: Cyclic amide
• Baeyer Villiger Oxidation
  • Similar to Beckmann but inserts oxygen instead
  • Discovered in 1899 by Adolph Baeyer and Victor Villiger
  • Converts cyclohexanone to a 7-membered ring (cyclic ester aka lactone)

Mechanism

• Reagents: Peracid (e.g., mCPBA)
  • Structure: Alkyl group, carbonyl group, oxygen-oxygen bond, and proton
  • Oxygen-oxygen bond is atypical and weak
• Steps
  • Protonation of ketone using peracid
  • Nucleophilic attack on carbon of protonated ketone
  • Formation of hydroxyl group and attachment of peracid
  • Rearrangement: Breaks C-C bond and inserts oxygen
  • Formation of 7-membered ring (lactone)
• Key Points
  • 6-membered rings are more stable and easy to form but 7-membered rings are harder
  • Rearrangement step similar to Beckmann
  • Favorable breaking of weak oxygen-oxygen bond
  • Formation of carboxylic acid from remaining peracid

Applications and Key Notes

• Useful for: Converting ketones to esters or cyclic ketones to lactones
• Retention of Stereochemistry: If substrate is linear, stereochemistry of migrating alkyl group is retained
• Reactivity: Peracids can oxidize other functional groups (e.g., pi bonds) affecting the reaction
• Best Substrate: Cyclohexanone (for smooth conversion to 7-membered lactone)

Conclusion

• Baeyer Villiger Oxidation is a valuable tool for organic synthesis
• Similar mechanism to Beckmann rearrangement but focuses on oxygen insertion