To selectively modify one functional group while leaving the other intact, we can use protecting groups to temporarily block the reactivity of one of the functional groups during the synthesis process. In this case, we have a compound with both a carboxylic acid and an alcohol functional group. Let's assume we want to modify the carboxylic acid group while leaving the alcohol group intact.1. Protecting the alcohol group:To protect the alcohol group, we can use a silyl ether protecting group, such as tert-butyldimethylsilyl TBS group. The reagents needed for this step are tert-butyldimethylsilyl chloride TBSCl and a base, such as imidazole.Reaction: Alcohol + TBSCl + imidazole TBS-protected alcohol2. Modification of the carboxylic acid group:With the alcohol group protected, we can now selectively modify the carboxylic acid group without interference. For example, we can convert the carboxylic acid to an ester or an amide using appropriate reagents.Esterification: Carboxylic acid + alcohol + acid catalyst e.g., H2SO4 or p-toluenesulfonic acid EsterAmidation: Carboxylic acid + amine + coupling reagent e.g., DCC or EDC Amide3. Deprotection of the alcohol group:After the desired modification of the carboxylic acid group, we can remove the TBS protecting group to restore the alcohol functionality. To achieve this, we use a mild acid or fluoride source, such as tetrabutylammonium fluoride TBAF or hydrochloric acid HCl .Deprotection: TBS-protected alcohol + TBAF or HCl AlcoholBy using protecting groups, we can selectively modify one functional group while leaving the other intact, allowing for a controlled synthesis of the desired compound.