OXALYL BROMIDE 1
O O
Oxalyl Bromide
(COBr)2
HO CN
(2)
90 °C
Br N Br
25%
O
Br
Br
O
Reaction of cyanogen with oxalyl bromide affords the tetra-
bromopyrazine (1) in greater than 70% yield (eq 3).6 A com-
pletely different product is obtained in this reaction when Oxalyl
[15219-34-8] C2Br2O2 (MW 215.82)
Chloride is used.
InChI = 1/C2Br2O2/c3-1(5)2(4)6
InChIKey = JAZLVNXWYDFQFE-UHFFFAOYAO
(reactive acid halide;1 heterocycle synthesis2) 70 140 °C
O OBu4N+ Br Br N Br
ć%
+
NC CN (3)
Physical Data: bp 16 17 C/10 mmHg; d 2.30 g cm-3.
HBr
Br Br
Br N Br
Form Supplied in: liquid or solution in CH2Cl2; commercially
70%
(1)
available.
Preparative Methods: originally prepared by Staudinger in 1913
by treating Oxalyl Chloride with HBr;3 a more recent report
describes a convenient alternative using Bromotrimethylsilane
which provides the reagent in 85% yield.4
1. Dowd, P.; Garner, P.; Schappert, R.; Irngartinger, H.; Goldman, A., J. Org.
Handling, Storage, and Precautions: corrosive; lachrymator. Use
Chem. 1982, 47, 4240.
in a fume hood.
2. (a) Vekemans, J.; Pollers-Wieers, C.; Hoornaert, G., J. Heterocycl. Chem.
1983, 20, 919. (b) Meerpoel, L.; Hoornaert, G., Synthesis 1990, 905.
3. Staudinger, H.; Anthes, H. B., Biochemistry 1913, 46, 1431.
Brominations. Oxalyl bromide is useful for the preparation
4. Schmidt, A. H.; Russ, M.; Grosse, D., Synthesis 1981, 216.
of acid bromides from carboxylic acids or salts.5 These acid bro-
5. Adams, R.; Ulich, L. H., J. Am. Chem. Soc. 1920, 42, 599.
mides are quite reactive and will often acylate nucleophiles under
6. Sundermeyer, J.; Roesky, H. W., Angew. Chem., Int. Ed. Engl. 1988, 27,
milder conditions than those required for the corresponding acid
1372.
chlorides.1
Oxalyl bromide has found use for the preparation of a number
Michael D. Ennis
of brominated heterocycles. Reaction of oxalyl bromide withÄ…-
The Upjohn Company, Kalamazoo, MI, USA
amino- orÄ…-hydroxynitriles yields substituted 2(1H)-pyrazinones
(eq 1)2a and 2H-1,4-oxazin-2-ones (eq 2),2b respectively.
Me
N O
+
(COBr)2
MeH2N CN
(1)
80 100 °C
Br N Br
49%
Avoid Skin Contact with All Reagents