Protecting group for phenol

Fig. 23. Representative protecting groups for phenolic and carboxylic acid-based systems, (a) The polymer-based protecting groups are fisted in order of increasing activation energy for acid-catalyzed deprotection, (b) Acid-labile monomeric dissolution inhibitors, a bifunctional system based on protected bisphenol A. (c) Another system that combines the function of dissolution inhibitor and PAG in a single unit.

An isopropyl ether was developed as a phenol protective group that would be more stable to Lewis acids than would be an aryl benzyl ether. The isopropyl group has been tested for use in the protection of the phenolic oxygen of tyrosine during peptide synthesis."... 

Thermolytic Cleavage of Allvlic and Benzvlic Ethers and Polvethers. The thermal lability of the types of ethers which are of interest in the context of this study was discovered during a thorough study of the application of certain benzylic carbonates as labile protecting groups for alcohols and phenols [IS]. It was observed that, under acid catalysis, the bis-methylcarbonate derivative of l-(4-hydroxyphenyl)ethanol (4, in Equation 1) was transformed into the benzylic ether (5) which then underwent clean acid-catalyzed thermolysis to the corresponding styrene (6) in very high yield [14]. 

The haloacetate group, also used as a protecting group for the phenolic function, can be removed by treatment with sodium telluride in DME, giving the parent phenol. ... 

Tetrahydropyranyl (TUP) and tetrahydrofuranyl ethers are important protecting groups for alcohols and phenols in organic synthesis, but they can also be converted to other useful functional groups [8, 118]. For example, allylation of a TUP ether should yield a highly functionalized molecule (Scheme 15). 

Dihydropyran is of value as a protecting group for alcohols and phenols, and to a lesser extent amines, carboxylic acids and thiols (B-67MI22403, B-81MI22404). The resulting tetrahydropyranyl ethers (736) are stable to base, but are readily cleaved under acidic conditions (Scheme 284). 

Most carbamates used as protective groups for amines are either acid-labile or base-labile. Deprotection proceeds by the mechanisms outlined in Figure 10.8. During the deprotection of acid-labile carbamates, carbocations are formed, which can alkylate electron-rich structural elements in a given substrate (e.g. phenols, thiols, indoles,... 

Literak, J., Wirz, J. and Klan, P. (2005) 2,5-Dimethylphenacyl carbonates A photoremovable protecting group for alcohols and phenols. Photochemical el... 

We said earlier that simple methyl ethers are inappropriate as protecting groups for OH because they are too hard to take off again. That is usually true, but not if the OH is phenolic—ArOH is an... 

An excellent means of protecting phenolic hydroxyl groups for reactions in alkaline media is by the formation of the methoxymethyl ether from the sodium salt of the phenol and chloromethyl ether, viz.,... 

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