Thallium(III) Nitrate Trihydrate1

Tl(NO3)3.3H2O

[13453-38-8]  · N3O9Tl  · Thallium(III) Nitrate  · (MW 444.47)

(oxidizing agent; Lewis acid for alkene cyclization)

Alternate Name: TTN.

Physical Data: mp 102-105 °C.

Solubility: sol water, organic solvents.

Form Supplied in: moist white crystals, hygroscopic; widely available. Drying: compound decomposes on heating.

Handling, Storage, and Precautions: all thallium compounds are extremely toxic to inhalation, skin contact, and ingestion. Toxicity is cumulative. Extreme caution should be used when handling these materials. Use in a fume hood.

Oxidations.

Thallium trinitrate is a powerful oxidant. A variety of substituted phenols undergo oxidation using TTN to provide quinones.2 For example, hydroquinones are oxidized to quinones in good yields. p-Alkoxyphenols are oxidized to p-quinone acetals in good yields by TTN in methanol (eq 1). Similarly, naphthols are oxidized to naphthoquinones using TTN. This oxidation proceeds in higher yields if TTN on Celite is used as the oxidant.3

Chalcones are oxidized under acidic conditions to 1,2-diketones using three equivalents of TTN (eq 2).4

TTN is a trihydrate and generally reactions with it are carried out under fairly acidic conditions. TTN oxidations in methanol as a solvent are also strongly acidic, since nitric acid is produced as a byproduct. Reactions that fail or proceed poorly with TTN (TTN in methanol or acetic acid), or where the substrates are acid sensitive, can be promoted by using a 1:1 mixture of methanol and trimethyl orthoformate (TMOF) (see Triethyl Orthoformate) or neat TMOF as solvent. Oxidation of cinnamaldehyde with TTN in methanol proceeds very slowly and produces seven products. On the other hand, cinnamaldehydes are rearranged to aryl malondialdehyde tetramethyl acetals in good yields on treatment with TTN in 1:1 MeOH-TMOF (eq 3).5

TTN adsorbed on Montmorillonite K10 is an effective reagent for the conversion of ketones to rearranged esters. For example, acetophenone is readily converted to phenylacetate on treatment with TTN/K-10 reagent (eq 4).6 Supported TTN reagents are practical, since product isolation from the insoluble inorganic byproducts is simple.

Alkene Oxidation.

Simple alkenes are converted to aldehydes or ketones in good yields using TTN. These reactions proceed with migration of the higher migratory aptitude substituent.7 The preparation of arylacetaldehyde dimethyl acetals by oxidative rearrangement of substituted styrenes using TTN proceeds in good yields (eq 5). The reaction proceeds through the exclusive migration of the aryl substituent and the yields are higher if TTN supported on K-10 is used as the oxidant.1b,6b

Cycloalkenes provide ring contracted aldehydes on oxidation with TTN under acidic conditions. Corey and Ravindranathan have used this methodology to prepare a key prostaglandin intermediate (eq 6).8 Similarly, enol ethers also undergo oxidative ring contraction on treatment with TTN (eq 7).9 If methanol is used as the solvent, the corresponding acetals are formed as the products.10 In contrast to the ring contractive oxidation of monocycloalkenes, bicyclic alkenes furnish nitrate esters on treatment with TTN.11 Exocyclic alkenes furnish ring enlarged ketones on oxidation with TTN (see Thallium(III) Perchlorate for similar reactions).12

Diarylalkynes are converted to 1,2-diketones using two equivalents of TTN (eq 8) and terminal alkynes are oxidized to carboxylic acids (eq 9).13

TTN can be used for electrophilic cyclizations of polyalkenes.14 The oxythallative cyclization of elemol acetate using TTN in acetic acid produces a guaiene diol after Lithium Aluminum Hydride reduction (eq 10).15 In contrast, Mercury(II) Acetate mediated cyclization of elemol produces the unrearranged cryptomeridiol.

Allylations Using Allysilanes and TTN.

Aromatic compounds are allylated using allylsilanes and TTN, but in poor yield.16 Allylsilanes are converted to allylic ethers (eq 11),17 N-allylic amides (eq 12),18 and allylic nitrates19 on treatment with TTN and the appropriate nucleophile.

Functional Group Interconversions.

TTN finds utility in a variety of functional group interconversions. Phenols are readily converted to anilines using TTN.20 Sulfides and selenides are converted to sulfoxides (eq 13) and selenoxides, respectively, on oxidation with TTN.21 Other transformations include the preparation of allene esters from a-alkyl-b-keto esters (eq 14),22 carbamates from isocyanides (eq 15),23 and lactones from g,d-unsaturated acids.24

TTN has been used to selectively deprotect bisthioacetals to give monothioacetals (eq 16).25 Simple thioacetals can also be deprotected using TTN. Oximes are converted to aldehydes or ketones in high yields on treatment with TTN in methanol at rt (eq 17).26


1. (a) McKillop, A. PAC 1975, 43, 463. (b) McKillop, A.; Taylor, E. C. In Comprehensive Organometallic Chemistry; Wilkinson, G., Ed.; Pergamon: Oxford, 1982; Vol. 7, p 465.
2. McKillop, A.; Perry, D. H.; Edwards, M.; Antus, S.; Farkas, L.; Nogradi, M.; Taylor, E. C. JOC 1976, 41, 282.
3. Crouse, D. J.; Wheeler, M. M.; Goemann, M.; Tobin, P. S.; Basu, S. K.; Wheeler, D. M. S. JOC 1981, 46, 1814.
4. McKillop, A.; Swann, B. P.; Ford, M. E.; Taylor, E. C. JACS 1973, 95, 3641.
5. Taylor, E. C.; Robey, R. L.; Liu, K.-T.; Favre, B.; Bozimo, H. T.; Conley, R. A.; Chiang, C.-S.; McKillop, A.; Ford, M. E. JACS 1976, 98, 3037.
6. (a) McKillop, A.; Swann, B. P.; Taylor, E. C. JACS 1973, 95, 3340. (b) Taylor, E. C.; Chiang, C.-S.; McKillop. A.; White, J. F. JACS 1976, 98, 6750.
7. McKillop, A.; Hunt, J. D.; Taylor, E. C.; Kienzle, F. TL 1970, 5275.
8. Corey, E. J.; Ravindranathan, T. TL 1971, 4753.
9. Kaye, A.; Neidle, S.; Reese, C. B. TL 1988, 29, 1841.
10. McKillop, A.; Hunt, J. D.; Kienzle, F.; Bigham, E.; Taylor, E. C. JACS 1973, 95, 3635.
11. Layton, W. J.; Brock, C. P.; Crooks, P. A.; Smith, S. L.; Burn, P. JOC 1985, 50, 5372.
12. Farcasiu, D.; Schleyer, P. v. R.; Ledlie, D. B. JOC 1973, 38, 3455.
13. (a) McKillop, A.; Oldenziel, O. H.; Swann, B. P.; Taylor, E. C.; Robey, R. L. JACS 1971, 93, 7331. (b) McKillop, A.; Oldenziel, O. H.; Swann, B. P.; Taylor, E. C.; Robey, R. L. JACS 1973, 95, 1296.
14. Anteunis, M.; DeSmet, A. S 1974, 868.
15. Renold, W.; Ohloff, G.; Norin, T. HCA 1979, 62, 985.
16. Ochiai, M.; Fujita, E.; Arimoto, M.; Yamaguchi, H. CPB 1983, 31, 86.
17. Ochiai, M.; Fujita, E.; Arimoto, M.; Yamaguchi, H. CPB 1984, 32, 5027.
18. Ochiai, M.; Tada, S.-I.; Arimoto, M.; Fujita, E. CPB 1982, 30, 2836.
19. Ochiai, M.; Fujita, E.; Arimoto, M.; Yamaguchi, H. CPB 1984, 32, 887.
20. Taylor, E. C.; Jagdmann, Jr., G.; McKillop, A. JOC 1978, 43, 4385.
21. Nagao, Y.; Ochiai, M.; Kaneko, K.; Maeda, A.; Watanabe, K.; Fujita, E. TL 1977, 1345.
22. Taylor, E. C.; Robey, R. L.; McKillop, A. JOC 1972, 37, 2797.
23. Kienzle, F. TL 1972, 1771.
24. Ferraz, H. M. C.; Ribeiro, C. R. SC 1992, 22, 399.
25. (a) Smith, R. A. J.; Hannah, D. J. SC 1979, 9, 301. (b) Fujita, E.; Nagao, Y.; Kaneko, K. CPB 1978, 26, 3743.
26. McKillop, A.; Hunt, J. D.; Naylor, R. D.; Taylor, E. C. JACS 1971, 93, 4918.

Mukund P. Sibi

North Dakota State University, Fargo, ND, USA



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