Boc2O

Boc2O, or di-tert-butyl dicarbonate, commonly known as Boc anhydride, is a widely used reagent in organic synthesis for installing the tert-butyloxycarbonyl (Boc) protecting group on amines. It is the standard reagent for preparing Boc-protected amines, which are valuable when selective reactions must be performed on other functional groups. While its primary use is amine protection, Boc2O can be employed in other contexts where a Boc carbamate is desired.

The typical reaction involves treating a primary or secondary amine with Boc2O in the presence of a base or catalyst, such as triethylamine, sodium bicarbonate, or DMAP, in an appropriate organic solvent. The result is a Boc-protected amine (a Boc carbamate) plus byproducts of tert-butanol and carbon dioxide. The procedure is generally mild and compatible with many functional groups, though moisture should be excluded to prevent hydrolysis of the reagent.

Deprotection of Boc groups is accomplished by acidolysis, commonly with trifluoroacetic acid or other strong acids, which removes the Boc group to regenerate the free amine and release carbon dioxide and tert-butanol. This acid-labile nature makes Boc protection convenient for stepwise synthesis, including peptide synthesis.

Properties and safety: Boc2O is a moisture-sensitive solid that should be stored in a dry, sealed container, typically under inert conditions. It can be an irritant and should be handled in a well-ventilated area or fume hood. Byproducts of its use are tert-butanol and carbon dioxide, which are typically removed during workup.

See also: Boc protecting group, carbamate protection, peptide synthesis.