Bocprotected

Bocprotected refers to a molecule in which a reactive amine has been converted into a tert-butyloxycarbonyl (Boc) carbamate, forming a Boc-protected amine. This protection temporarily masks the basic and nucleophilic amine, allowing other transformations to proceed selectively. The Boc group is one of the most widely used protecting groups for amines in organic synthesis, favored for its stability under many reaction conditions and its relatively straightforward, acid-labile removal.

Boc protection is a common strategy in organic synthesis to prevent amines from reacting during multi-step sequences. The Boc group is formed by attaching a tert-butyloxycarbonyl moiety to the nitrogen to give a Boc carbamate. It is typically installed by reacting a primary or secondary amine with di-tert-butyl dicarbonate (Boc2O) in the presence of a base such as diisopropylethylamine (DIPEA) or triethylamine, in an inert solvent like dichloromethane or THF. The resulting Boc-protected amine is stable to many bases and to a wide range of reagents.

Deprotection is achieved under acidic conditions. Trifluoroacetic acid (TFA) in dichloromethane and hydrogen chloride in dioxane are common choices, typically at room temperature. The Boc group is cleaved to liberate the free amine with concomitant release of carbon dioxide and tert-butanol.

Advantages include compatibility with many protective schemes, ease of installation and removal, and orthogonality to many other protecting groups. Disadvantages include the need for acidic conditions for removal, which can affect acid-sensitive functionalities, and added steric bulk that can hinder certain reactions. Boc protection is often contrasted with Fmoc protection, which is base-labile and used in different peptide synthesis strategies.