tert-Butyloxycarbonyl protecting group
The tert-butyloxycarbonyl protecting group or tert-butoxycarbonyl protecting group[1] (BOC group) is a protecting group used in organic synthesis.
The BOC group can be added to amines under aqueous conditions using di-tert-butyl dicarbonate in the presence of a base such as sodium hydroxide:
Protection of amines can also be accomplished in
Removal of the BOC group in
Sequential treatment with
-
R2NCO2tBu + Me3SiI → R2NCO2SiMe3 + tBuI(1)
-
R2NCO2SiMe3 + MeOH → R2NCO2H + MeOSiMe3(2)
-
R2NCO2H → R2NH + CO2(3)
Amine protection
The tert-butyloxycarbonyl (Boc) group is used as a protecting group for amines in organic synthesis.
Common amine protection methods
- Simple rapid stirring of a mixture of the amine and on-water reaction.[11]
- Heating a mixture of the amine to be protected and di-tert-butyl dicarbonate in tetrahydrofuran (THF) at 40 °C[12]
- Add the amine to sodium hydroxide and di-tert-butyl dicarbonate in water and THF at 0 °C then warm to ambient temperature.[13]
- Heating a mixture of the amine to be protected and di-tert-butyl dicarbonate in a biphasic mixture of chloroform and aqueous sodium bicarbonate at reflux for 90 minutes.[14]
- Add the amine to di-tert-butyl dicarbonate, 4-dimethylaminopyridine (DMAP), and acetonitrile (MeCN) at ambient temperature[15]
BOC-protected amines are prepared using the reagent di-tert-butyl-iminodicarboxylate. Upon deprotonation, this reagent affords a doubly BOC-protected source of NH−
2, which can be N-alkylated. The approach is complementary to the Gabriel synthesis of amines.
Common amine deprotection methods
- Mix the protected carbamate to be deprotected with 3 M hydrochloric acid (HCl) in ethyl acetate for 30 min at ambient temperature[16]
- Heat the carbamate in a mixture of aqueous hydrochloric acid and toluene at 65 °C[17]
- Dissolving desired protected compound in a 50/50 mix of dichloromethane and trifluoroacetic acid[18]
References
- ^ "Rules for abbreviation of protecting groups" (PDF). IUPAC. iupac.org. 2013.
- .
- PMID 14723531.
- PMID 15469321.
- PMID 744685.
- ISBN 9783527641574.
- .
- .
- PMID 25376704.
- .
- PMID 16836380.
- ISBN 9780471697541.
- PMID 27966983.
- PMID 16591972.
- PMID 14723531.
- .
- .
- ^ "Boc Deprotection - TFA".