OXALYL BROMIDE
1
Oxalyl Bromide
O
Br
Br
O
[15219-34-8]
C
2
Br
2
O
2
(MW 215.82)
InChI = 1/C2Br2O2/c3-1(5)2(4)6
InChIKey = JAZLVNXWYDFQFE-UHFFFAOYAO
(reactive acid halide;
1
heterocycle synthesis
2
)
Physical Data:
bp 16–17
◦
C/10 mmHg; d 2.30 g cm
−3
.
Form Supplied in:
liquid or solution in CH
2
Cl
2
; commercially
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
Handling, Storage, and Precautions:
corrosive; lachrymator. Use
in a fume hood.
Brominations. Oxalyl bromide is useful for the preparation
of acid bromides from carboxylic acids or salts.
5
These acid bro-
mides are quite reactive and will often acylate nucleophiles under
milder conditions than those required for the corresponding acid
chlorides.
1
Oxalyl bromide has found use for the preparation of a number
of brominated heterocycles. Reaction of oxalyl bromide with α-
amino- or α-hydroxynitriles yields substituted 2(1H)-pyrazinones
(eq 1)
2a
and 2H-1,4-oxazin-2-ones (eq 2),
2b
respectively.
MeH
2
N
CN
+
N
N
O
Br
Br
Me
(COBr)
2
(1)
80–100 °C
49%
HO
CN
N
O
O
Br
Br
(COBr)
2
(2)
90 °C
25%
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
Chloride is used.
Br
O
O
Br
Br
N
N
Br
Br
Br
NC CN
(3)
70–140 °C
Bu
4
N
+
Br
–
+
(1)
HBr
70%
1.
Dowd, P.; Garner, P.; Schappert, R.; Irngartinger, H.; Goldman, A., J. Org.
Chem. 1982
, 47, 4240.
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.
4.
Schmidt, A. H.; Russ, M.; Grosse, D., Synthesis 1981, 216.
5.
Adams, R.; Ulich, L. H., J. Am. Chem. Soc. 1920, 42, 599.
6.
Sundermeyer, J.; Roesky, H. W., Angew. Chem., Int. Ed. Engl. 1988, 27,
1372.
Michael D. Ennis
The Upjohn Company, Kalamazoo, MI, USA
Avoid Skin Contact with All Reagents