CHEM 130 Lecture Notes - Lecture 8: Alkene, Sunedison, Enol
Document Summary
Thanks to their relative lack of chemical reactivity, ethers have proven to be useful protective groups for alcohols and phenols. As outlined in the following diagram, many ether protective groups have been introduced to serve this purpose. Most of these are prepared by acid-catalyzed addition to an alkene or by. Acronyms are used for common protective groups, an example being the thp (tetrahydropyranyl) ethers prepared from dihydropyran (dhp), as shown at top left. Whenever a protective or blocking group is used to facilitate a synthetic operation, it normally must be removed once the operation is complete. In this respect it is useful to have an assortment of protective groups for which different chemical conditions accomplish this cleavage. Two of the acid-catalyzed addition reactions, shown at the top left, generate acetal derivatives incorporating the alcohol moiety. These acetals may be hydrolyzed by aqueous acid, with the thp derivative reacting more rapidly than the acetone analog.
