Bis(tri-n-butyltin) Oxide

(n-Bu3Sn)2O

[56-35-9]  · C24H54OSn2  · Bis(tri-n-butyltin) Oxide  · (MW 596.20)

promotes the oxidation of secondary alcohols and sulfides with Br2; O- and N-activations; dehydrosulfurizations; hydrolysis catalyst)

Physical Data: bp 180 °C/2 mmHg; d 1.170 g cm-3.

Solubility: sol ether and hexane.

Form Supplied in: colorless oil.

Handling, Storage, and Precautions: (Bu3Sn)2O should be stored in the absence of moisture. Owing to the toxicity of organostannanes, this reagent should be handled in a well-ventilated fume hood. Contact with the eyes and skin should be avoided.

Oxidations.

Benzylic, allylic, and secondary alcohols are oxidized to the corresponding carbonyl compounds by using (Bu3Sn)2O-Bromine.1 This procedure is quite useful for selective oxidation of secondary alcohols in the presence of primary alcohols, which are inert under these conditions (eqs 1-3).2 (Bu3Sn)2O-N-Bromosuccinimide can also be applied to the selective oxidation of secondary alcohols (eq 4).3

(Bu3Sn)2O-Br2 oxidizes sulfides to sulfoxides in CH2Cl2 without further oxidation to sulfones, even in the presence of excess reagent (eq 5).4 This procedure is especially useful for sulfides having long, hydrophobic alkyl chains, for which solubility problems are often encountered in the Sodium Periodate oxidation in aqueous organic solvents. Oxidation of sulfenamides to sulfinamides can be achieved without formation of sulfonamides using the reagent (eq 6).4

(Bu3Sn)2O-Br2-Diphenyl Diselenide in refluxing CHCl3 transforms alkenes into a-seleno ketones (eq 7).5

O- and N-activations.

(Bu3Sn)2O has been used in the activation of hydroxy groups toward sulfamoylations, acylations, carbamoylations, and alkylations because conversion of alcohols to stannyl ethers enhances the oxygen nucleophilicity. Tributylstannyl ethers are easily prepared by heating the alcohol and (Bu3Sn)2O, with azeotropic removal of water. Sulfamoylation of alcohols can be achieved via tributyltin derivatives in high yields, whereas direct sulfamoylation gives low yields (eq 8).6 This activation can be used for selective acylation of vicinal diols (eq 9).7 In carbohydrate chemistry this approach is extremely useful for the regioselective acylation without the use of a blocking-deblocking technique (eq 10).8 The order of the activation of hydroxy groups on carbohydrates has been investigated, and is shown in partial structures (1), (2), and (3).9 Regioselective carbamoylation can also be accomplished by changing experimental conditions (eq 11).10 On the other hand, alkylations of the tin derivatives are sluggish and less selective than acylations under similar conditions. Regioselective alkylation of sugar compounds, however, can be carried out in high yield by conversion to a tributyltin ether followed by addition of alkylating agent and quaternary ammonium halide catalysts (eq 12).11

This O-activation is also effective for intramolecular alkylations such as oxetane synthesis (eq 13).12 Similar N-activation has been used in the synthesis of pyrimidine nucleosides (eq 14).13

Dehydrosulfurizations.

The thiophilicity of tin compounds is often utilized in functional group transformations. Thus conversion of aromatic and aliphatic thioamides to the corresponding nitriles can be accomplished by using (Bu3Sn)2O in boiling benzene under azeotropic conditions (eq 15).14

Hydrolysis.

Esters are efficiently hydrolyzed with (Bu3Sn)2O under mild conditions (eq 16).15

Transformation of primary alkyl bromides or iodides to the corresponding primary alcohols is achieved in good yield by using (Bu3Sn)2O-Silver(I) Nitrate (or Silver(I) p-Toluenesulfonate) (eq 17),16 whereas this method is not applicable to secondary halides due to elimination.

(Bu3Sn)2O is a useful starting material for the preparation of tributyltin hydride, which is a convenient radical reducing reagent in organic synthesis. Thus Tri-n-butylstannane is easily prepared by using exchange reactions of (Bu3Sn)2O with polysiloxanes (eq 18).17

Related Reagents.

Tri-n-butyl(methoxy)stannane.


1. Saigo, K.; Morikawa, A.; Mukaiyama, T. CL 1975, 145.
2. Ueno, Y.; Okawara, M. TL 1976, 4597.
3. Hanessian, S.; Roy, R. CJC 1985, 63, 163.
4. Ueno, Y.; Inoue, T.; Okawara, M. TL 1977, 2413.
5. Kuwajima, I.; Shimizu, M. TL 1978, 1277.
6. Jenkins, I. D.; Verheyden, J. P. H.; Moffatt, J. G. JACS 1971, 93, 4323.
7. (a) Ogawa, T.; Matsui, M. T 1981, 37, 2363. (b) David, S.; Hanessian, S. T 1985, 41, 643.
8. (a) Crowe, A. J.; Smith, P. J. JOM 1976, 110, C57. (b) Blunden, S. J.; Smith, P. J.; Beynon, P. J.; Gillies, D. G. Carbohydr. Res. 1981, 88, 9. (c) Ogawa, T.; Matsui, M. Carbohydr. Res. 1977, 56, C1. (d) Hanessian, S.; Roy, R. JACS 1979, 101, 5839. (e) Arnarp, J.; Loenngren, J. CC 1980, 1000. (f) Ogawa, T.; Nakabayashi, S.; Sasajima, K. Carbohydr. Res. 1981, 96, 29.
9. Tsuda, Y.; Haque, M. E.; Yoshimoto, K. CPB 1983, 31, 1612.
10. (a) Ishido, Y.; Hirao, I.; Sakairi, N.; Araki, Y. H 1979, 13, 181. (b) Hirao, I.; Itoh, K.; Sakairi, N.; Araki, Y.; Ishido, Y. Carbohydr. Res. 1982, 109, 181.
11. (a) Alais, J.; Veyrières, A. JCS(P1) 1981, 377. (b) Veyrières, A. JCS(P1) 1981, 1626.
12. Biggs, J. TL 1975, 4285.
13. Ogawa, T.; Matsui, M. JOM 1978, 145, C37.
14. Lim, M.-I.; Ren, W.-Y.; Klein, R. S. JOC 1982, 47, 4594.
15. Mata, E. G.; Mascaretti, O. A. TL 1988, 29, 6893.
16. Gingras, M.; Chan, T. H. TL 1989, 30, 279.
17. Hayashi, K.; Iyoda, J.; Shiihara, I. JOM 1967, 10, 81.

Hiroshi Sano

Gunma University, Kiryu, Japan



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