Iodine-Copper(II) Acetate

I2-Cu(OAc)2.H2O
(I2)

[7553-56-2]  · I2  · Iodine-Copper(II) Acetate  · (MW 253.80) (Cu(OAc)2)

[142-71-2]  · C4H6CuO4  · Iodine-Copper(II) Acetate  · (MW 181.65) (Cu(OAc)2.H2O)

[6046-93-1]  · C4H8CuO5  · Iodine-Copper(II) Acetate  · (MW 199.67)

(iodination of ketones, alkenes, and aromatic compounds; oxidation of cycloalkenes and alkyl-substituted ketones)

Physical Data: Cu(OAc)2.H2O: mp 115 °C; d 1.882 g cm-3.

Solubility: Cu(OAc)2.H2O: sol H2O, ethanol; slightly sol ether, glycerol.

Form Supplied in: Cu(OAc)2.H2O: dark blue-green solid.

Handling, Storage, and Precautions: both reagents are toxic and should be handled in a fume hood.

Iodination.

The I2-Cu(OAc)2 reagent can be used for the directed iodination of ketones in acetic acid at 60 °C, leading to the corresponding a-iodo ketones (eqs 1 and 2).1 Cyclohexene and steroidal alkenes react with Iodine in MeOH or AcOH in the presence of Copper(II) Acetate to give trans-1-iodo-2-methoxycyclohexane (eq 3)2 and steroidal trans-iodo acetates (eq 4) in good yields.2 Activated arenes such as mesitylene, aniline, and anisole can be iodinated in high yield by this reagent (eq 5).3 Although phenol is iodinated mainly at the ortho-position, aniline and anisole are iodinated at the para-position. Iodination of estrogen derivatives having a hydroxy group at C-3 regioselectively affords 2-iodoestradiol derivatives (eq 6).4

Oxidation.

Much work has been reported on the cis-hydroxylation of alkenes using the Prévost reaction and its Woodward modification. The reaction of alkenes with I2 and Cu(OAc)2 in AcOH yields a mixture of products which is hydrolyzed by KOH in MeOH-H2O to provide cis-diols. In the case of 5a-cholest-2-ene, the more hindered 2b,3b-diol is produced in high yield (eq 7). Cyclohexene and cycloheptene similarly give the cis-diol in good yield. This synthetic method affords several advantages over the Prévost reaction and other methods used heretofore.5

The reaction of diosphenol with I2 and Cu(OAc)2 in AcOH-H2O (5:1) at 80 °C gives 3-hydroxythymo-1,4-quinone (79%).6 Moreover, treatment of 3-iodo-3,6-dialkyl-1,2-cyclohexanediones with I2-Cu(OAc)2 gives 3-hydroxy-2,5-dialkyl-1,4-benzoquinones in 38-88% yield.9 On the other hand, reaction with Cu(OAc)2 under reflux affords 3,3-dihydroxy-2,2,5,5-tetraalkyl-4,4-diphenoquinones (eq 8).7 A similar oxidation has been used for the synthesis of 3-alkyl-1,2-cyclohexanediones from 2-alkylcyclohexanones (40-70%) (eq 9).8


1. Horiuchi, C. A; Satoh, J. Y. S 1981, 312.
2. (a) Georgoulis, C.; Valery, J. M. BSF(2) 1975, 1431. (b) Horiuchi, C. A.; Satoh, J. Y. BCJ 1987, 60, 426.
3. Horiuchi, C. A.; Satoh, J. Y. BCJ 1984, 57, 2691.
4. (a) Horiuchi, C. A.; Satoh, J. Y. CC 1982, 671. (b) Horiuchi, C. A.; Haga, A.; Satoh, J. Y. BCJ 1986, 59, 2459.
5. Horiuchi, C. A.; Satoh, J. Y. CL 1988, 1209.
6. Horiuchi, C. A.; Suzuki, Y.; Takahashi, M.; Satoh, J. Y. CL 1987, 393.
7. Horiuchi, C. A.; Suzuki, Y. BCJ 1989, 62, 2919.
8. Horiuchi, C. A.; Kiyomiya, H.; Takahashi, M; Suzuki, Y. S 1989, 785.

C. Akira Horiuchi

Rikkyo (St. Paul's) University, Tokyo, Japan



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