tert-Butyloxycarbonyl (Boc) is a protecting group often used in the synthesis of organic compounds. Boc is specifically used to protect amine in the solid phase synthesis of peptides (Green, T. W.; Wuts, P. G. M., Protective Groups in Organic Synthesis, Wiley-Interscience: New York, 1999, pp 518-525, 736-739). Cleavage of Boc from amino acids, at the last stage, is carried out with trifluroacetic acid or with hydrochloric acid. Di-tert-butyl dicarbonate (BOC-anhydride) and 4-dimethylaminopyridine (DMAP) are used to prepare Boc protected compounds in the absence of any catalyst. Selective cleavage of the Boc group in the presence of other protecting groups is possible when using AlCl3. Boc protection of nitrogen is done in the synthesis of chiral imines from aldehydes. In the Mori synthesis of (-)-isostrychnine from N-tosylamine, after the reduction of the nitrile to amine, the amine is protected with Boc.
Stable Boc-alpha-aminoacylbenzotriazoles derived from Boc-alpha-amino acids are used in the synthesis of chiral alpha-protected amino acid amides. (Boc-alpha-aminoacyl)benzotriazoles are used in the preparation of N-(acylamino)amides. Chiral diamines are prepared from Boc-protected amino acid-derived secondary amides. Selective Boc protection of the secondary amine in the presence of the primary amine is done by condensing the primary amine with benzaldehyde, followed by Boc protection at the secondary amine and hydrolysis of the imine to give the free primary amine.