1-(t-Butoxycarbonyl)imidazole

[49761-82-2]  · C8H12N2O2  · 1-(t-Butoxycarbonyl)imidazole  · (MW 168.20)

(a reagent for the introduction of the t-butoxycarbonyl group at nucleophilic sites1)

Physical Data: mp 44.5-47 °C; bp 64 °C/1 mmHg.

Solubility: sol CH2Cl2, CHCl3, THF, hexane, acetone, and DMF, among others.

Form Supplied in: not commercially available.

Preparative Method: 1-(t-butoxycarbonyl)imidazole (1) can be prepared from the reaction of imidazole and 1,2,2,2-tetrachloroethyl-t-butyl carbonate1a or the reaction of t-butanol and N,N-carbonyldiimidazole1b in high yield. The reagent has been reported to be stable at rt.2

Handling, Storage, and Precautions: anhydrous conditions are recommended.

t-Butoxycarbonylation.

The amine functions of various amino acids have been protected with the t-butoxycarbonyl (Boc) group by (1) (eq 1).1b,3 Polar anhydrous organic solvents have been used in general, although traces of moisture can be tolerated.

Alkylation of (1), or its silver perchlorate complex, produces water-soluble imidazolium salts with enhanced electrophilic character (eq 2).4 The perchlorate and tetrafluoroborate salts of this type are remarkably stable and they have been used to protect amino acids in aqueous media (eq 3).4

Selective protection of a single amine in alkyl diamines by (1) is reported (eq 4).5 Furthermore, the reaction of Hydrazine with (1) affords t-butoxycarbonylhydrazide, which is a useful reagent in peptide chemistry.1b

Incorporation of the Boc group at the aromatic nitrogen of the pyridine ring system (eq 5)6 and at a carbon nucleophile (eq 6)7 by (1) has also been reported.

Formation of O-Alkylperoxycarbonic Acids.

Epoxidation of alkenes in a biphasic system could be performed by in situ generation of O-alkylperoxycarbonic acids (eq 7).2 The reaction is typically carried out by the addition of 35% Hydrogen Peroxide to a solution of (1) and the alkene substrate in an organic solvent. The epoxide of cholesteryl acetate was prepared quantitatively in a 3:1 ratio of a- to b-epoxide by this method.

Related Reagents.

1-t-Butoxycarbonyl-1,2,4-triazole.


1. (a) Barcelo, G.; Senet, J. P.; Sennyey, G. JOC 1985, 50, 3951. (b) Klee, W.; Brenner, M. HCA 1961, 2151.
2. Tsunokawa, Y.; Iwasaki, S.; Okuba, S. TL 1982, 23, 2113.
3. Chou, C. Y. U. S. Patent 4 837 332, 1989 (CA 1988, 109, 6966k).
4. Guibé-Jampel, E.; Bram, G.; Wakselman, M.; Vilkas, M. SC 1973, 111.
5. Devan, P. B.; Hertzberg, R. P. U.S. Patent 4 942 227, 1990 (CA 1987, 107, 232 672b).
6. Wakselman, M.; Guibé-Jampel, E. Pept., Proc. Eur. Pept. Symp., 14th 1976, 131.
7. Bourgeois, M. J.; Montaudon, E.; Campagnole, M.; Maillard, B. BSB 1982, 91, 871.

Ioannis Grapsas & Shahriar Mobashery

Wayne State University, Detroit, MI, USA



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