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Di-tert-butyl dicarbonate



Di-tert-butyl dicarbonate
IUPAC name Di-t-butyl dicarbonate
Other names di-tert-butyl pyrocarbonate
Boc anhydride
Boc2O
Identifiers
CAS number 24424-99-5
SMILES CC(C)(C)OC(=O)OC(=O)OC(C)(C)C
Properties
Molecular formula C10H18O5
Molar mass 218.25 g/mol
Appearance colourless solid
Density 0.95 g/cm3
Melting point

22–24 °C

Boiling point

56–57 °C (0.5 mm Hg)

Solubility in water insol
Solubility in other solvents most organic solvents
Structure
Dipole moment 0 D
Hazards
Main hazards flammable
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)

Infobox disclaimer and references

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.

Additional recommended knowledge

Contents

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:[5]

References

  1. ^ Wakselman, M. “Di-t-butyl Dicarbonate” in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289.
  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. doi:10.1021/ol0361599
    D. M. Shendage, R. Fröhlich, G. Haufe, Org. Lett., 2004, 6, 3675-3678. doi:10.1021/ol048771l
  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. doi:10.1021/jo051940a
  5. ^ 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).
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Di-tert-butyl_dicarbonate". A list of authors is available in Wikipedia.
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