[35952-85-3]  · C36H30Bi2Cl2O  · m-Oxobis(chlorotriphenylbismuth)  · (MW 967.52)

(mild oxidant for alcohols and a-glycol cleavage4)

Physical Data: mp 148-154 °C.2

Solubility: sol CH2Cl2, CHCl3, THF, hot benzene.

Preparative Methods: by treatment of Triphenylbismuth Dichloride with NaOH in MeOH-acetone.3

Handling, Storage, and Precautions: stable white solid. Can be stored in the refrigerator under inert gas (N2 or Ar) for some weeks. This reagent should be handled in a fume hood.

Oxidation of Alcohols.3,4

Oxobis(chlorotriphenylbismuth) is a mild oxidant for primary, secondary, allylic, and benzylic alcohols, which are converted smoothly and in high yields to the corresponding carbonyl derivatives under mild conditions of pH and temperature. The oxidation is generally performed by addition of the alcoholic substrate to a solution of the reagent in CH2Cl2 in the presence of K2CO3 or KHCO3 at rt or under reflux. The carbonyl products are easily separated from the triphenylbismuth byproduct, either by chromatography on silica gel, or by heating the reaction mixture with acetic acid followed by aqueous workup and ether extraction. Unfortunately this latter procedure curtails the advantage of the near neutral reaction conditions. The reagent is especially effective for the oxidation of allylic alcohols. Examples of the efficiency of the reagent are found in the oxidation of natural products. The oxidation of methyl hederagenin to methyl hederagonate was performed in 24 h with a 36% yield (eq 1), significantly better than the previously reported oxidation.5 In the synthesis of digitoxin derivatives, the oxidation of a furyl alcohol to the 15-keto derivative was achieved in 94% yield (eq 2).6 In the oxidation of cembranolide diterpenes,7 the reaction was accomplished without disturbing the oxirane ring (eq 3).

1,2-Glycols are cleaved under the same reaction conditions to afford the two derived carbonyl components. However, this reaction has not been developed as much as the glycol cleavage by triphenylbismuth carbonate.

Related Reagents.

See also the oxidizing reagents Triphenylbismuth Carbonate, Triphenylbismuth Diacetate, and Triphenylbismuth Dichloride; for glycol cleavage, see Triphenylbismuthine and Triphenylbismuth Carbonate.

1. (a) Barton, D. H. R.; Finet, J. P. PAC 1987, 59, 937. (b) Abramovitch, R. A.; Barton, D. H. R.; Finet, J. P. T 1988, 44, 3039. (c) Kitchin, J. P. In Organic Syntheses by Oxidation with Metal Compounds; Mijs, W. J.; De Jonge, C. R. H. I., Eds.; Plenum: New York, 1986; p 817.
2. Goel, R. G.; Prasad, H. S. JOM 1972, 36, 323.
3. Barton, D. H. R.; Kitchin, J. P.; Motherwell, W. B. CC 1978, 1099.
4. Barton, D. H. R.; Kitchin, J. P.; Lester, D. J.; Motherwell, W. B.; Papoula, M. T. B. T 1981, 37, Suppl.1, 73.
5. Jacobs, W. A. JBC 1925, 63, 631.
6. Atwal, K. S.; Sahoo, S. P.; Tsai, T. Y. R.; Wiesner, K. H 1982, 19, 641.
7. Ahond, A.; Bowden, B. F.; Coll, J. C.; Fourneron, J. D.; Mitchell, S. J. AJC 1979, 32, 1273.

Jean-Pierre Finet

Université de Provence, Marseille, France

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