Triphenylbismuth Diacetate1


[7239-60-3]  · C22H21BiO4  · Triphenylbismuth Diacetate  · (MW 558.41)

(oxidation of alcohols and glycols;3 O- and N-phenylation9,14,16)

Physical Data: mp 187-189 °C.2

Solubility: sol CH2Cl2, CHCl3; insol ether, MeOH.

Preparative Methods: prepared by treatment of Triphenylbismuth Carbonate with Acetic Acid in CH2Cl2,3 or by Lead(IV) Acetate oxidation of Triphenylbismuthine.2a The best yield (60%) is obtained by treatment of Ph3Bi with Pb(OAc)4 in AcOH for 2 h at rt, followed by addition of water, filtration, and recrystallization (CH2Cl2-ether).

Handling, Storage, and Precautions: stable white solid; can be stored under inert gas in the refrigerator for some months. Use in a fume hood.

Oxidation of Alcohols and 1,2-Glycols.

Under basic conditions (either Potassium Carbonate or an organic base such as 1,8-Diazabicyclo[5.4.0]undec-7-ene or 1,1,3,3-Tetramethylguanidine), this reagent oxidizes alcohols to the corresponding carbonyl compounds.3,4 In a fashion similar to Ph3BiCO3, Ph3Bi(OAc)2 reacts with vicinal glycols in the presence of K2CO33 or with the stannylene derivatives of vicinal glycols5 under neutral conditions to afford the two corresponding carbonyl fragments in high yield.

Phenylation of Alcohols.

In the absence of base, Ph3Bi(OAc)26,7 and the related reagent Ph4BiOCOCF38 (prepared by reaction of Ph5Bi with 1 equiv of CF3CO2H, mp 120-132 °C, C26H20BiF3O2, MW 630.44, [83566-43-2]) react with primary and secondary alcohols to afford mostly the corresponding O-phenyl ethers with various amounts of oxidation products. In the presence of a copper catalyst, 62-97% of the O-phenyl ethers can be obtained with simple alcohols and Ph3Bi(OAc)2 (eq 1). As copper catalyst, Copper(II) Chloride, Copper(I) Chloride, Copper(II) Acetate, or metallic Copper can be used.9

Miscellaneous Phenylation Reactions.

In a very simple procedure, a-, b-, g-, or d-diols can be efficiently monophenylated by simple reflux of the diol and Ph3Bi(OAc)2 (1 equiv) in CH2Cl2 until disappearance of the diol (eq 2).10 For secondary-tertiary diols, the secondary O-phenyl ethers are obtained, and for axial-equatorial diols, the axial ethers are obtained. With an excess of Ph3Bi(OAc)2, the bis-ether can be obtained.9 Addition of a small amount of Cu(OAc)2 (0.1 equiv or less) increases the reaction rate significantly, and the reaction can then be performed in a variety of solvents (eq 3).9 Moreover, addition of chiral pyridine oxazolines leads to a moderate optical induction in the case of the meso-cis-1,2-cyclohexanediol.11

Whereas thiols are oxidized with Ph3BiCO3 or Ph3BiCl2 and base or Ph4BiOCOCF3 and base, they gave the corresponding phenyl thioether when treated with Ph4BiOCOCF3 under neutral or acidic conditions.12 However, in the case of hydroxythiols, the copper-catalyzed reaction with Ph3Bi(OAc)2 leads to mixtures of mono- and di-O-phenylated disulfides.9

Phenols react with Ph4BiOCOCF3 (under neutral conditions or with acid catalysis) in benzene under reflux to afford moderate to good yields of the O-phenyl ethers.13 Faster rates and better yields can be obtained through copper catalysis. However, Ph3Bi(OAc)2 under copper metal catalysis in CH2Cl2 at rt effects a more efficient and selective O-phenylation of electron-poor as well as electron-rich phenols (eq 4). Except for highly hindered phenols, such as 2,6-di-t-butylphenol, yields are generally high.14

Enols are subject to mono-O-phenylation with Ph4BiOCOCF3 under neutral or, preferably, acidic conditions.12 Copper catalysis leads to some improvement. Enols can also give the O-phenyl ethers by reaction with Ph3Bi(OAc)2 or the analogous reagent Ph3Bi(OCOCF3)2 (prepared by action of CF3CO2H on Ph3BiCO3, mp 133 °C, C22H15BiF6O4, MW 666.35, [83566-43-2]) under copper metal catalysis. Yields are moderate to good.14

Phenylation of Amines.

Under metallic copper catalysis, Ph3Bi(OAc)2 and Ph3Bi(OCOCF3)2 react with aliphatic, heterocyclic, or aromatic amines in CH2Cl2 at rt to give the mono-N-phenyl derivatives in high yields (eq 5).15,16 A number of a-amino acid esters are also selectively mono-N-phenylated under these conditions.17 A wide range of variously substituted anilines have been mono- or di-N-phenylated with these reagents (eq 6). The most conveniently prepared reagent [Ph3Bi(OAc)2] is less reactive than Ph3Bi(OCOCF3)2. Thus after 45 min, mesitylamine gives 40% of N-phenylmesitylamine with the former reagent, but 95% with the latter. Similarly, 4-nitroaniline gives 22% and 98%, respectively. Indoles are N- or C-3 phenylated only with Ph3Bi(OCOCF3)2 under copper catalysis.18

The system Ph3Bi(OAc)2 + copper catalysis provides a broader spectrum of reactivity than the similar aryllead triacetates under copper catalysis, which do not effect phenol O-arylation but which do react with anilines to give high yields of unsymmetrical diarylamines.19

1. (a) Finet, J. P. CRV 1989, 89, 1487. (b) Freedman, L. D.; Doak, G. O. In The Chemistry of the Metal-Carbon Bond; Hartley, F. R., Ed.; Wiley: New York, 1989; Vol. 5, Chapter 9.
2. (a) Wittig, G.; Hellwinkel, D. CB 1964, 97, 789. (b) Wieber, M. Gmelin Handbuch der Anorganische Chemie; Springer: Berlin, 1977; Band 47, Bismut-Organische Verbindungen, p 38.
3. Barton, D. H. R.; Kitchin, J. P.; Lester, D. J.; Motherwell, W. B.; Papoula, M. T. B. T 1981, 37, W73.
4. Dodonov, V. A.; Gushchin, A. V.; Brilkina, T. G. ZOB 1985, 55, 73.
5. David, S.; Thieffry, A. TL 1981, 22, 2885.
6. Dodonov, V. A.; Brilkina, T. G.; Gushchin, A. V. ZOB 1981, 51, 2380.
7. Dodonov, V. A.; Gushchin, A. V.; Brilkina, T. G. ZOB 1985, 55, 2514.
8. Barton, D. H. R.; Finet, J. P.; Motherwell, W. B.; Pichon, C. JCS(P1) 1987, 251.
9. Barton, D. H. R.; Finet, J. P.; Pichon, C. CC 1986, 65.
10. (a) David, S.; Thieffry, A. TL 1981, 22, 5063; (b) David, S.; Thieffry, A. JOC 1983, 48, 441.
11. (a) Brunner, H.; Obermann, U.; Wimmer, P. JOM 1986, 316, C1; (b) Brunner, H.; Obermann, U.; Wimmer, P. OM 1989, 8, 821.
12. Barton, D. H. R.; Blazejewski, J. C.; Charpiot, B.; Finet, J. P.; Motherwell, W. B.; Papoula, M. T. B.; Stanforth, S. P. JCS(P1) 1985, 2667.
13. Barton, D. H. R.; Bhatnagar, N. Y.; Blazejewski, J. C.; Charpiot, B.; Finet, J. P.; Lester, D. J.; Motherwell, W. B.; Papoula, M. T. B.; Stanforth, S. P. JCS(P1) 1985, 2657.
14. Barton, D. H. R.; Finet, J. P.; Khamsi, J.; Pichon, C. TL 1986, 27, 3619.
15. Dodonov, V. A.; Gushchin, A. V.; Brilkina, T. G. ZOB 1985, 55, 466.
16. Barton, D. H. R.; Finet, J. P.; Khamsi, J. TL 1986, 27, 3615.
17. Barton, D. H. R.; Finet, J. P.; Khamsi, J. TL 1989, 30, 937.
18. Barton, D. H. R.; Finet, J. P.; Khamsi, J. TL 1988, 29, 1115.
19. Barton, D. H. R.; Donnelly, D. M. X.; Finet, J. P.; Guiry, P. J. JCS(P1) 1991, 2095.

Jean-Pierre Finet

Université de Provence, Marseille, France

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