DI-TERT-BUTYL DICARBONATE

General
Systematic name	Di-t-butyl dicarbonate
Other names	di-tert-butyl pyrocarbonate Boc anhydride Boc2O
Molecular formula	C10H18O5
SMILES	CC(C)(C)OC(=O)OC(=O)OC(C)(C)C
InChI	InChI=1/C10H18O5/c1- 9(2,3)14-7(11)13-8 (12)15-10(4,5)6/h1-6H3
Molar mass	218.25 g/mol
Appearance	colourless solid
CAS number	[24424-99-5]
Properties
Density and phase	0.95 g/cm3
Solubility in water	insol
Other solvents	most organic solvents
Melting point	22–24 °C
Boiling point	56–57 °C (0.5 mm Hg)
Structure
Dipole moment	0 D
Hazards
MSDS	External MSDS
Main hazards	flammable
Supplementary data page
Structure and properties	''n'' 1.4103
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	IR 1810, 1765 cm–1 NMR = 1.50 (CCl4)
Related compounds
Related compounds	t-Butyl Chloroformate Phosgene
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

'Di-''tert''-butyl dicarbonate' is a reagent widely used in organic synthesis.^[1] This carbonate ester reacts with amines to give N-''tert''-butoxycarbonyl or so-called ''t''-BOC derivatives. These derivatives do not behave as amines, which allows certain subsequent transformations to occur that would have otherwise affected the amine functional group. The ''t''-BOC can later be removed from the amine using acids. Thus, ''t''-BOC serves as a protective group, for instance in solid phase peptide synthesis. It is stable to most bases and nucleophiles, allowing for an orthogonal Fmoc protection.

Contents

Protection and deprotection of amines

Other uses

Preparation

References

Protection and deprotection of amines

The Boc group can be added to the amine under aqueous conditions using di-''tert''-butyl dicarbonate in the presence of a base such as sodium bicarbonate. Protection of the amine can also be accomplished in acetonitrile solution using 4-dimethylaminopyridine (DMAP) as the base.
Removal of the ''t''-BOC in amino acids can be accomplished with strong acids such as trifluoroacetic acid neat or in dichloromethane, or with HCl in methanol.^[2]
[3]

Other uses

The synthesis of 6-acetyl-1,2,3,4-tetrahydropyridine, an important bread aroma compound from 2-piperidone was accomplished using t-boc anhydride.^[4]
(See Maillard reaction). The first step in this reaction sequence is the formation of the carbamate from the reaction of the secondary amine with boc anhydride in acetonitrile with DMAP as a base.

Preparation

Di-''tert''-butyl dicarbonate is inexpensive, so it is usually purchased. Classically, this compound is prepared from tert-butanol, carbon dioxide, phosgene, using DABCO as a base:Barry M. Pope, Yutaka Yamamoto, and D. Stanley Tarbell, Dicarbonic acid, bis(1,1-dimethylethyl) ester, Organic Syntheses, Coll. Vol. 6, p.418 ('1988'); Vol. 57, p.45 ('1977').

References

1. Wakselman, M. “Di-''t''-butyl Dicarbonate” in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. .
2. Robert M. Williams, Peter J. Sinclair, Duane E. DeMong, Daimo Chen, and Dongguan Zhai, ''4-Morpholinecarboxylic acid, 6-oxo-2,3-diphenyl-, 1,1-dimethylethyl ester, (2S,3R)-'', Organic Syntheses, Vol. 80, p.18 ('2003')
3. E. A. Englund, H. N. Gopi, D. H. Appella, Org. Lett., 2004, 6, 213-215.
D. M. Shendage, R. Fröhlich, G. Haufe, Org. Lett., 2004, 6, 3675-3678.
4. Tyler J. Harrison and Gregory R. Dake, ''An Expeditious, High-Yielding Construction of the Food Aroma Compounds 6-Acetyl-1,2,3,4-tetrahydropyridine and 2-Acetyl-1-pyrroline'', J. Org. Chem., '2005'; 70(26) pp 10872 - 10874.