[479-33-4]  · C29H20O  · Tetraphenylcyclopentadienone  · (MW 384.49)

(reactive diene for Diels-Alder reactions)

Alternate Names: tetracyclone; cyclone.

Physical Data: mp 217-220 °C.

Solubility: soluble in ethanol, benzene, xylene, acetic acid.

Form Supplied in: black-violet crystalline solid; commercially available. Drying: may be recrystallized from ethanol-benzene.

Handling, Storage, and Precautions: no special precautions; follow manufacturer's label instructions.

General Discussion.

Tetraphenylcyclopentadienone is readily prepared in high yield by the condensation of benzil with dibenzyl ketone under basic catalysis.2 Less commonly, the reagent has been prepared from the alkaline Potassium Ferricyanide oxidation of 2,4,5,6-tetraphenyl resorcinol in modest yield.3 The reagent is most frequently employed as a reactive diene in the Diels-Alder reaction with a large number of vinylic and alkynic dienophiles, especially arynes (eq 1).1,4 This subject has been reviewed.1

The reaction can be followed visually by the disappearance of the characteristic intense purple color. Depending on the reaction conditions, the initial cycloadduct may retain the carbonyl bridge (eq 2).5,6

With alkyne dienophiles, loss of CO is universal. The reaction of the reagent with Dimethyl Acetylenedicarboxylate has been studied extensively in a wide range of solvents (eq 3).5

Less common reactions involving the reagent have also been reported. For example, treatment of the cyclooctyne-silver nitrate complex with the reagent affords the decarbonylated cycloadduct in high yield.7 Reaction of the O-tosylhydroxylamine of the reagent with aryl Grignard or lithium nucleophiles gives the corresponding imine, which is converted to the arylamine by treatment with excess Hydroxylamine in aqueous pyridine.8 Reduction of the reagent with Lithium Aluminum Hydride and Aluminum Chloride (1:1) in ether affords the useful diene tetraphenylcyclopentadiene in excellent yield.9 The reagent has been used as a scavenger for singlet oxygen.10

Related Reagents.


1. Allen, C. F. H. CRV 1962, 62, 653.
2. Johnson, J. R.; Grummit, O. OSC 1955, 3, 806.
3. Gusten, H.; Kirsch, G.; Schulte-Frohlinde, D. AG(E) 1967, 6, 948.
4. Haddadin, M. J. OS 1966, 46, 107.
5. Dilthey, W.; Thewalt, I.; Trosken, O. CB 1934, 67, 1959.
6. Allen, C. F. H.; Ryan, R. W.; VanAllan, J. A. JOC 1962, 27, 778.
7. Wittig, G.; Dorsch, H.-L. LA 1968, 711, 46.
8. Hagopian, R. A.; Therien, M. J.; Murdoch, J. R. JACS 1984, 106, 5753.
9. Cava, M. P.; Narasimhan, K. JOC 1969, 34, 3641.
10. (a) Murray, R. W.; Lumma, W. C.; Lin, J. W.-P. JACS 1970, 92, 3205. (b) Brennan, M. E. CC 1970, 956. (c) Sanderson, J. R.; Story, P. R. JOC 1974, 39, 3183.

Keith R. Buszek

Kansas State University, Manhattan, KS, USA

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