lecture 6

• Meerwein-Ponndorf-verley reduction (MPV)

  -Lewis acid used to catalyse a hydride shift from alcohol to ketone

  -forms a new ketone and a new alcohol

  -Reversible

  -excess alcohol used as driving force
• MPV using i-PrOH


  -If i-PrOH is used as a solvent and reagent the resulting ketone is acetone

  -easily removed by evaporation after reaction is completed
• MPV reduction- lewis acid requirements

  -must coordinate to both the alcohol and ketone to form a six membered ring transition state

  -Hydride shift can occur as an intramolecular reaction
• MPV reaction in reverse

  -Oppenauer oxidation

  -Oxidation of secondary alcohols in the presence of an excess of a ketone
• Ozonolysis


  -Passing electric discharge through oxygen

  -3O2 to 2O
• Ozone


  -Powerful oxidising agent

  -Breaks C=C to produce two carbonyl containing fragments
• Ozonolysis workups

  -i) O3, -78 ii)Me2S = two aldehydes, reductive

  -i) O3, -78 ii)H2O2 = two carboxylic acids, oxidative

  -i) O3, -78 ii)NaBH4 = two alcohols (primary), reductive
• Cleavage of double bonds

  -2 step addition-oxidation

  -1) O5O4

  -2) NaIO4

  -Often higher yield