A protecting group or protective group is introduced into a molecule by chemical modification of a functional group to obtain chemoselectivity in a subsequent chemical reaction, facilitating multistep organic synthesis.
*Boc for the t-butoxycarbonyl group
*Cbz or Z for the carboxybenzyl group
*Fmoc for the fluorenylmethoxycarbonyl group
*Alloc for the allyloxycarbonyl group
*Troc for the trichloroethoxycarbonyl group
*TMS, TBDMS, TES, TBDPS, TIPS, ... for various silyl ether groups
*PMB for the 4-methoxybenzyl group
*MOM for the methoxymethyl group
*THP for the 2-tetrahydropyranyl group