deprotected

Deprotected refers to the state of a molecule after the deliberate removal of a protecting group from a functional group in chemical synthesis. Protecting groups are chemical moieties temporarily attached to reactive sites to prevent unwanted reactions during multi-step sequences. Deprotection is the controlled process by which the original functional group is revealed and becomes available for further transformations or biological activity.

In organic synthesis, deprotection allows selective manipulation of specific sites, enabling the construction of complex molecules such as pharmaceuticals, natural products, and polymers. It is designed to be compatible with other steps and to minimize side reactions, often requiring orthogonal strategies so that only the intended group is removed at a given stage.

Common protecting groups and methods include: for amines, Boc and Cbz are acid- and hydrogenolysis-labile protecting groups, while Fmoc is base-labile; deprotection occurs under acid, hydrogenolysis, or base conditions, respectively. For alcohols and phenols, silyl ethers (e.g., TBS) and benzyl or acetyl groups are common, deprotection achieved by fluoride sources, acid, hydrogenolysis, or hydrolysis. For carboxyl groups, esters such as methyl or tert-butyl esters are removed by hydrolysis or transesterification; carbonyls may be protected as acetals or ketals and deprotected under acidic conditions. In peptide synthesis, protecting groups are chosen to be orthogonal, allowing sequential deprotection with minimal impact on other groups.

Key considerations include orthogonality, selectivity, and compatibility with solvents and reagents. Deprotection steps are often among the final stages in synthesis and must preserve desired stereochemistry and overall yield. Beyond synthetic chemistry, deprotection concepts appear in bioconjugation and material sciences, where temporary masking enables controlled activation.