Protection phenol groups, 2- ethanol

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]. 

A straightforward synthesis (Scheme 3) of a furocoumarin-thymidine furan-side adduct was developed <1997JOC2630>. The methoxymethyl (MOM)-protecting group in 33 was removed in 91% yield with ethanolic HCl, and the resulting phenol 34 was condensed with dimethylacetamide dimethyl acetal in the presence of 4 A... 

The addition of a little barium hydroxide to 2-hydroxyacetophenone and benzaldehyde in 96% ethanol followed by refluxing of the reaction mixture during 4 hours afforded the chalcone (benzylidene 2-hydroxyacetophenone) in 89% yield without the need for protection of the phenolic hydroxyl group and unaccompanied by impurities (reT74). 

Protection of phenolic hydroxyl groups. Rail et al. encountered difficulties In methoxymethylation of the phenol (1) by standard procedures (reaction with lodium ethoxide, ethanol, and chloromethyl methyl ether). They then found... 

In order to achieve controlled polymerization from die bdk ligand, an ethanol moiety is introduced to the phenol site to provide a primary alcohol site, and a less sterically crowded enviromnent for initiation (Figure 4). The alcohol requires protection in order to prevent deprotonation under die basic reaction conditions required for the ester and ketone condensation. A number of protecting groups were screened for this purpose, and one promising strategy involves methoxymethyl (MOM) protection. The formation of the MOM ether proceeds in nearly quantitative yield. After the condensation, the MOM group can be removed with aqueous HCl in THF. 

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