"The most important protecting groups for alcohols are ethers and mixed acetals. … Methyl ethers are readily accessible via the Williamson ether synthesis, but harsh conditions are required to deprotect them. … t-Butyl ethers are readily prepared and are stable to nucleophiles, hydrolysis under basic conditions, organometallic reagents, metal hydrides, and mild oxidations. … Benzyl ethers are quite stable under both acidic and basic conditions and toward a wide variety of oxidizing and reducing reagents. Hence, they are frequently used in organic syntheses as protecting groups. … The PMB ether, also referred to as an MPM ether [(4-methoxyphenyl)methyl], is less stable to acids than a benzyl ether. … Trityl ethers have played an important role in the selective protection and manipulation of -CH2OH groups in carbohydrate chemistry. … The popularity of silicon protecting groups stems from the fact that they are readily introduced and removed under mild condition. Moreover, a wide variety of silylating agents are available for tailor-made protection of ROH groups. The THP group is a widely used protecting group; it is readily introduced by reaction of the enol ether dihydropyran with an alcohol in the presence of an acid catalyst. … The use of carboxylic acid esters as protective groups for alcohols is limited since they may undergo acyl substitution, hydrolysis or reduction."