Chemistry Reference
In-Depth Information
N-Benzoyl amino acids 1333 react with excess oxalyl chloride at room tempera-
ture to form intermediates 1334, treatment of which with alcohols affords 4-sub-
stituted 2-phenyloxazole-5-carboxylates 1335 [1009].
O
R
1
R
1
O
1. - H
2
O
N
(COCl)
2
OH
R
1
Cl
O
Ph
Ph
N
H
2. MeOH
O
COOMe
Cl
O
Ph
N
O
1333
1334
1335
Acid chlorides are also formed when oxalyl chloride reacts with some saturated
hydrocarbons in the presence of light or a peroxide. Replacement of hydrogen by
COCl occurs [954, 1010].
Thus, when a mixture of cyclohexane 1336 (0.3 mol), oxalyl chloride (0.2 mol),
and dibenzoyl peroxide (1.2 g) was refluxed for 24 h, the cyclohexanecarboxylic acid
chloride 1337 was obtained in modest yield.
O
(COCl)
2
, (PhCOO)
2
Cl
+CO+HCl
50 %
1336
1337
In some cases, an olefinic hydrogen can be displaced by COCl [1011].
Ph
H
Ph
(COCl)
2
C
CH
2
Ph
COCl
Ph
50 %
1338
1339
Typical procedure. [1012]:
On refluxing 1,1-diphenylethylene 1338 (6.5 g) with
oxalyl chloride (4.5 g) for 3-4 h, the acid chloride 1339 was obtained in 50% yield.
The yield of this reaction could be raised to 95% by using 5 mol of oxalyl chloride
per mol of alkene. Neither light nor peroxides have any effect on this reaction,
which is apparently ionic.
Cyclohexene and trimethylethylene failed to react. Anthracene 1340 undergoes
substitution without catalysis [1013].
COCl
(COCl)
2
67 %
1340
1341
