Iodine-Cerium(IV) Ammonium Nitrate

I2-(NH4)2Ce(NO3)6
(I2)

[7553-56-2]  · I2  · Iodine-Cerium(IV) Ammonium Nitrate  · (MW 253.80) ((NH4)2Ce(NO3)6)

[15078-94-1]  · CeH8N8O18  · Iodine-Cerium(IV) Ammonium Nitrate  · (MW 548.28)

(iodination of ketones, alkenes, and a,b-unsaturated ketones; oxidative aromatization of cyclohexenones; cis-hydroxylation of alkenes)

Physical Data: (NH4)2Ce(NO3)6: dec 225 °C.

Solubility: (NH4)2Ce(NO3)6: sol H2O (136 g/100 mL at 12 °C), MeOH, EtOH, MeCN.

Form Supplied in: (NH4)2Ce(NO3)6: orange-red monoclinic crystals. Drying: (NH4)2Ce(NO3)6 can be dried by heating at 90 °C for 8 h.

Handling, Storage, and Precautions: bottles of (NH4)2Ce(NO3)6 should be kept tightly sealed to preclude contact with moisture and air. This reagent should be handled in a fume hood.

Iodination.

Oxidative iodination of ketones can be accomplished by utilizing Cerium(IV) Ammonium Nitrate (CAN) (0.5 molar equiv) and Iodine (0.5 molar equiv) at 25-50 °C in AcOH or MeOH (eq 1). The reaction is regioselective, providing the more highly substituted a-iodo ketones in very good yields (eq 2). This method is superior to an earlier alternative using I2-Cu(OAc)2 in AcOH.1 Direct iodination of some ketones using I2-CAN in MeCN or AcOH at 80 °C-reflux gives the corresponding a,a-diiodo ketones in good yield (eq 3).2 Asakura and Robins have reported a mild procedure for selective preparation of 5-iodouracil nucleosides with I2-CAN (eq 4).3 The method provides advantages over procedures reported heretofore. Cycloalkenes and steroidal alkenes react with I2 in ROH (R = Me, Et, n-Pr, and i-Pr) in the presence of CAN to give the corresponding vicinal alkoxyiodocycloalkanes in good yield (eq 5). In the case of t-BuOH, trans-iodo nitrates are obtained (eq 6).4 Moreover, it is interesting that cycloalka-1,3-dienes react with I2 in the presence of CAN to give the trans-2-alkoxy-1-iodo compounds, not the 1,4-addition products (eq 7).5 In the case of a,b-unsaturated ketones and esters, trans-b-alkoxy-a-iodo derivatives are also obtained in 70-92% yield (eq 8).6 Similar reagents have been used for the synthesis of aryl iodides (eq 9).7

Oxidations.

Much work has been reported on the cis-hydroxylation of alkenes using the Prévost reaction and Woodward modification. The reaction of alkenes with I2 and CAN in AcOH gives a mixture of products which can be hydrolyzed by KOH in MeOH-H2O to cis-diols in high yields (eq 10).8 The oxidative aromatization of a,b-unsaturated cyclohexenones to ethers has been investigated.9-14 The reaction of cyclohexenone derivatives with I2-CAN in ROH (R = Me, Et, n-Pr, i-Pr, Bu) under reflux gives the corresponding alkyl phenyl ethers in good yields (eq 11). This reaction is also applicable to diols (ethylene glycol, 1,3-propanediol, 1,4-butanediol).15


1. Horiuchi, C. A.; Kiji, S. CL 1988, 31.
2. Horiuchi, C. A.; Takahashi, E. BCJ, 1994, 67, 271.
3. Asakura, J.; Robins, M. J. TL 1988, 29, 2855; JOC 1990, 55, 4928.
4. Horiuchi, C. A.; Nishio, Y.; Gong, D.; Fujisaki, T.; Kiji, S. CL 1991, 607.
5. Horiuchi, C. A.; Hosokawa, H.; Kanamori, M.; Muramatsu, Y.; Ochiai, K.; Takahashi, E. CL 1995, 13.
6. Horiuchi, C. A.; Ochiai, K.; Fukunishi, H. CL 1994, 185.
7. Sugiyama, T. BCJ 1981, 54, 2847.
8. Horiuchi, C. A.; Gong, D.; Fujisaki, T., unpublished results.
9. Doering, W. von E; Beringer, F. M. JACS 1949, 71, 2221.
10. Turner, R. B.; Meschino, J. A. JACS 1958, 80, 4862.
11. Hartman, J. A.; Tomasewski, A. J.; Dreiding, A. S. JACS 1956, 78, 5662.
12. Tamura, Y.; Yoshimoto, Y. CI(L) 1980, 888.
13. Bondon, D; Pietrasanta, Y.; Pucci, B. TL 1977, 821.
14. Hirao, T.; Mori, M.; Oshiro, Y. JOC 1990, 55, 358.
15. Horiuchi, C. A.; Fukunishi, H.; Kajita, M.; Yamaguchi, A; Kiyomiya, H.; Kiji, S. CL 1991, 1921.

C. Akira Horiuchi

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



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