The most efficient protecting group strategy for selectively protecting a primary alcohol in the presence of other functional groups during organic synthesis would be to use a protecting group that is specifically reactive towards primary alcohols and can be easily removed later in the synthesis.One common protecting group for primary alcohols is the silyl ether group, such as tert-butyldimethylsilyl TBS or triisopropylsilyl TIPS . These groups can be selectively introduced to primary alcohols using their corresponding chlorides TBSCl or TIPSCl in the presence of a mild base, such as imidazole or pyridine. This reaction typically occurs under mild conditions and is selective for primary alcohols over secondary alcohols and other functional groups.To remove the silyl ether protecting group later in the synthesis, a fluoride source, such as tetra-n-butylammonium fluoride TBAF or hydrogen fluoride HF in pyridine, can be used. This reaction is also mild and selective, allowing for the deprotection of the primary alcohol without affecting other functional groups.In summary, the most efficient protecting group strategy for selectively protecting a primary alcohol in the presence of other functional groups during organic synthesis is to use a silyl ether protecting group, such as TBS or TIPS, which can be easily introduced and removed under mild and selective conditions.