Protection for the Hydroxyl Group, Including 1,2‐ and 1,3‐Diols

Hydroxyl groups are present in a number of compounds of biological and synthetic interest, including nucleosides, carbohydrates, steroids, macrolides, polyethers, and the side chain of some amino acids. Many chemical transformations such as oxidation, acylation, halogenation with phosphorus or hydrogen halides, dehydration reactions, and many more require hydroxyl group protection. Ethers are among the most used protective groups in organic synthesis. They vary from the simplest, most stable, methyl ether to the more elaborate, substituted, trityl ethers developed for use in nucleotide synthesis. The Mitsunobu reaction is usually used to introduce an ester with inversion of configuration, but in carbohydrate vicinal diols a monobenzoate is obtained with retention of configuration. Cyclic carbonates and cyclic boronates have also found considerable use as protective groups.