Oxalyl Chloride-Aluminum Chloride


[79-37-8]  · C2Cl2O2  · Oxalyl Chloride-Aluminum Chloride  · (MW 126.92) (AlCl3)

[7446-70-0]  · AlCl3  · Oxalyl Chloride-Aluminum Chloride  · (MW 133.33)

(useful for the preparation of benzoyl chlorides and derivatives;1 2-acylpyrrole synthesis2)

Physical Data: see entries for Oxalyl Chloride and Aluminum Chloride.

Handling, Storage, and Precautions: Caution! Both phosgene and carbon monoxide are formed upon mixing equimolar amounts of oxalyl chloride and aluminum chloride at room temperature. Use this reagent only in an efficient fume hood.

General Discussion.

The combination of oxalyl chloride and aluminum chloride is a reagent system which has proven generally useful for the preparation of substituted benzoic acid derivatives. For example, 4-alkyl- or 4-halobenzoyl chlorides can be prepared in good yield and free of any positional isomers using this reagent combination.1 The reaction is equivalent to a Friedel-Crafts acylation using Phosgene, and in fact the presence of both carbon monoxide and phosgene has been detected by IR spectroscopy in the gases formed upon mixture of these reagents. The reaction works best for alkylated aromatic substrates and fails when attempted on those bearing either activating (such as alkoxy) or deactivating substituents. Carbon disulfide appears to be the solvent of choice for these reactions. The acid chloride products obtained by this method can also be directly subjected to either hydrolysis3 or alcoholysis4 to provide the corresponding carboxylic acids or esters (eqs 1 and 2).

Similarly, the combination of oxalyl chloride/aluminum chloride will introduce an acyl group at the 2-position of 1-(phenylsulfonyl)pyrrole (1) to give the corresponding acid chloride (2) (eq 3).2

There is a report describing the reaction of paracyclophane (3) with oxalyl chloride/aluminum chloride under mild conditions (-10 °C) to produce the glyoxyl chloride derivative (4) in quantitative yield.5 Refluxing (4) for 3 h in chlorobenzene effects complete decarbonylation to the acid chloride (5).

An interesting ring closure of the tricarbonylmyrceneiron complex (6) has been reported.6 Treatment of (6) with oxalyl chloride/aluminum chloride (1:2) in dichloromethane at -78 °C led to the immediate formation of two diastereomeric keto chlorides (7). Dehydrohalogenation of one of the stereoisomers using Silver(I) Nitrate afforded the enone (8) (eq 5).

1. Neubert, M. E.; Fishel, D. L. OS 1983, 61, 8.
2. Kakushima, M.; Hamel, P.; Frenette, R.; Rokach, J. JOC 1983, 48, 3214.
3. (a) Sokol, P. E. OS 1964, 44, 69. (b) Shaw, J. E.; Stapp, P. R. J. Colloid Interface Sci. 1985, 107, 231.
4. Arnold, D. R.; Nicholas, A. M. de P.; Snow, M. S. CJC 1985, 63, 1150.
5. Psiorz, M.; Schmid, R. CB 1987, 120, 1825.
6. Birch, A. J.; Pearson, A. J. CC 1976, 601.

Michael D. Ennis

The Upjohn Company, Kalamazoo, MI, USA

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