Alcoholic hydroxyl ketal derivatives

Acetonide formation is the most commonly used protection for 1,2- and 1,3-diols. The acetonide has been used extensively in carbohydrate chemistry to mask selectively the hydroxyls of the many different sugars. In preparing ace-tonides of triols, the 1,2-derivative is generally favored over the 1,3-derivative which in turn is favored over the 1,4-derivative, but the extent to which the 1,2-acetonide is favored is dependent upon the structure of the triol. Note that the 1,2-selectivity for the ketal from 3-pentanone is better than that from acetone. Its greater lipophilicity also improves the isolation of the ketals of small alcohols such as glycerol. ... 

---