Acetonide

In organic chemistry, an acetonide is the functional group composed of the cyclic ketal of a diol with acetone. The more systematic name for this structure is an isopropylidene ketal. Acetonide is a common protecting group for 1,2- and 1,3-diols.^[1] The protecting group can be removed by hydrolysis of the ketal using dilute aqueous acid.

General structure of a 1,2-acetonide. The diol is shown in blue, the acetone part in red.

Example

The acetonides of small di- and triols, as well as many sugars and sugar alcohols, are common.^[2] The hexaol mannitol reacts with 2,2-dimethoxypropane to give the bis-acetonide, which oxidizes to give the acetonide of glyceraldehyde:^[3][4]

(CHOHCHOHCH₂OH)₂ + 2 (MeO)₂CMe₂ → (CHOHCHCH₂O₂CMe₂)₂ + 4 MeOH

(CHOHCHOCH₂OCMe₂)₂ + [O] → 2 OCHCHCH₂O₂CMe₂ + H₂O

An example of its use as a protecting group in a complex organic synthesis is the Nicolaou Taxol total synthesis. It is a common protecting group for sugars and sugar alcohols, a simple example being solketal.

The acetonides of corticosteroid are used in dermatology, because their increased lipophilicity leads to better penetration into the skin.^[5][6]

• Fluclorolone acetonide
• Fluocinolone acetonide
• Triamcinolone acetonide

See also

• Acetophenide
• Acroleinide
• Aminobenzal
• Cyclopentanonide
• Pentanonide