Copper(II) Sulfate-Pyridine


[7758-99-8]  · CuO4S  · Copper(II) Sulfate-Pyridine  · (MW 249.68) (py)

[110-86-1]  · C5H5N  · Copper(II) Sulfate-Pyridine  · (MW 79.10)

(hydration of aryl-substituted oxiranes;1 oxidation of hydroxy ketones2)

Physical Data: see Copper(II) Sulfate and Pyridine.

Hydration of Aryl-Substituted Epoxides.

Aryl-substituted oxiranes undergo stereospecific cis ring opening in the presence of copper(II) sulfate and pyridine in an aqueous phosphate buffer (pH 7), producing cis-diols. Hydration occurs at the benzylic position of the aryl-substituted epoxide. Trans cleavage products are also obtained in less than 15% yield (eq 1).1

It was also shown that cis-chlorohydrins could be prepared from aryl-substituted epoxides in a reaction involving copper sulfate, pyridine, and Lithium Chloride in THF (eq 2). Lithium chloride increases the catalytic activity of copper(II) sulfate in this reaction. However, when methanol is used as a solvent, cis-glycol monomethyl ethers are obtained (eq 3). Under such conditions, a reaction with alkyl-substituted epoxides does not take place. Substitution occurs at the benzylic position.1

Oxidation of Hydroxy Ketones.

Oxidation of benzoin by oxygen (or air) in the presence of stoichiometric amounts of copper(II) sulfate in aqueous pyridine gives benzil in 80% yield (eq 4).2 Similarly, furil was obtained from furoin in 63% yield (eq 5)3 and a-hydroxybenzyl 2-pyrrolyl ketone was oxidized to phenyl-2-pyrrolylglyoxal in 95% yield (eq 6).4

Related Reagents.

Copper(II) Sulfate; Potassium Permanganate-Copper(II) Sulfate.

1. Imuta, M.; Ziffer, H. JACS 1979, 101, 3990.
2. Clarke, H. T.; Dreger, E. E. OSC 1941, 1, 87.
3. Hartman, W. W.; Dickey, J. B. JACS 1933, 55, 1228.
4. Gardner, T. S.; Wenis, E.; Lee, J. JOC 1958, 23, 823.

Edward J. Parish & Stephen A. Kizito

Auburn University, AL, USA

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