To selectively protect an amine group in the presence of hydroxyl and carboxyl groups, a chemist can use a protecting group that reacts specifically with the amine group and does not react with the hydroxyl or carboxyl groups. One such protecting group is the tert-butyloxycarbonyl BOC group.The BOC group can be introduced to the amine group using di-tert-butyl dicarbonate BOCO in the presence of a base, such as triethylamine EtN . The reaction conditions are mild and do not affect the hydroxyl and carboxyl groups.Here's the general reaction scheme:R-NH + BOCO + EtN R-NH-BOC + EtN-HCl + COWhere R represents the rest of the organic molecule.Once the amine group is protected with the BOC group, the chemist can carry out the desired reactions on the hydroxyl and carboxyl groups without affecting the amine group. After completing the necessary transformations, the BOC group can be removed to regenerate the free amine group. This can be done using a mild acid, such as trifluoroacetic acid TFA , which cleaves the BOC group without affecting the other functional groups.R-NH-BOC + TFA R-NH + TFA-BOCBy using the BOC protecting group, a chemist can selectively protect the amine group in the presence of hydroxyl and carboxyl groups during the synthesis of a complex organic molecule.