Dimethyl Sulfoxide-Silver Tetrafluoroborate


[67-68-5]  · C2H6OS  · Dimethyl Sulfoxide-Silver Tetrafluoroborate  · (MW 78.13) (AgBF4)

[14104-20-2]  · AgBF4  · Dimethyl Sulfoxide-Silver Tetrafluoroborate  · (MW 194.68)

(reagent for conversion of alkyl halides to aldehydes and ketones)

Physical Data: DMSO: mp 18.55 °C; bp 189 °C/760 mmHg; 76 °C/16 mmHg; d (25 °C) 1.0958 g cm-3; dielectric constant (25 °C) 46.7. AgBF4: mp 200 °C.

Solubility: DMSO: miscible with water and most organic solvents. AgBF4: sol water, ether, toluene, nitromethane, DMSO; moderately sol benzene and cyclohexane.

Form Supplied in: DMSO: clear anhyd liquid, widely available. AgBF4: crystalline white solid, widely available. Drying: DMSO: generally quite dry when freshly opened, but very hygroscopic; distill from CaH2 under reduced pressure. AgBF4: very hygroscopic; dry in vacuo at 80 °C.

Handling, Storage, and Precautions: see Dimethyl Sulfoxide and Silver(I) Tetrafluoroborate.

Silver-assisted nucleophilic displacement of halide to form an alkoxysulfonium ion, followed by deprotonation, most commonly by Triethylamine,1 effectively converts benzylic and allylic halides and some primary1b and secondary alkyl halides1a,b,f,5 to the corresponding aldehydes or ketones at room temperature (eq 1,1d eq 2,1e eq 3,1f and eq 41j). While avoiding the higher temperatures generally required by the Kornblum method2 (NaHCO3 (+NaI3), DMSO, 100-150 °C), the silver-assisted reaction has the disadvantage of higher cost. Most oxidations have been accomplished with silver tetrafluoroborate; however, there are successful examples which used Silver(I) Nitrate4 or hexafluorophosphate.5 The same type of conversion has been accomplished with trialkylamine oxides,6 ion-exchange polymer-bound chromate ion,7 the classical Sommelet reaction,8 and other methods.9 Oxidation of the corresponding alcohols is the obvious alternative.1e,k On the other hand, bromination of an allylic or benzylic methyl group with N-Bromosuccinimide followed by DMSO-AgBF4 oxidation1h,i,j is a useful substitute for direct oxidation of the hydrocarbon.10

Typically, a solution of 1 mmol of halide (usually bromide or iodide) and 1.1-2.0 mmol of silver salt in 1-5 mL of DMSO is stirred at rt for 10 min to 24 h. Excess triethylamine is then added, the mixture is stirred for an additional 15 min and diluted with water. The product is isolated in the usual fashion. Several examples are given in Table 1.1a,1b

1. (a) Lemal, D. M.; Fry, A. J. JOC 1964, 29, 1673. (b) Ganem, B.; Boeckman, R. K., Jr. TL 1974, 917. (c) Roedig, A.; Fouré, M.; Försch, M. CB 1977, 110, 322. (d) Terao, S.; Kato, K.; Shiraishi, M.; Morimoto, H. JCS(P1) 1978, 1101. (e) Fraser-Reid, B.; Iley, D. E. CJC 1979, 57, 645. (f) Langlois, N.; Andriamialisoa, R. Z. JOC 1979, 44, 2468. (g) Tyrell, J. A., III; McEwen, W. E. JOC 1981, 46, 2476. (h) Swenton, J. S.; Anderson, D. K.; Jackson, D. K.; Narasimhan, L. JOC 1981, 46, 4825. (i) Nagao, Y.; Yamada, S.; Fujita, E. TL 1983, 24, 2291. (j) Liu, W.-C.; Parker, W. L.; Brandt, S. S.; Atwal, K. S.; Ruby, E. P. J. Antibiot. 1984, 37, 1313. (k) Frei, B.; Huxley, P.; Maienfisch, P.; Mereyala, H. B.; Rist, G.; O'Sullivan, A. C. HCA 1990, 73, 1905.
2. (a) Kornblum, N.; Jones, W. J.; Anderson, G. J. JACS 1959, 81, 4113. (b) Review: Epstein, W. W.; Sweat, F. W. CRV 1967, 67, 247. (c) See also Tidwell, T. T. S 1990, 857. (d) Mancuso, A. J.; Swern, D. S 1981, 165.
3. Dave, P.; Byun, H.-S.; Engel, R. SC 1986, 16, 1343.
4. Ghera, E.; Plemenitas, A.; Ben-David, Y. S 1984, 504.
5. Raucher, S. TL 1978, 26, 2261.
6. See, for example, (a) Godfrey, A. G.; Ganem, B. TL 1990, 31, 4825. (b) Griffith, W. P.; Jolliffe, J. M.; Ley, S. V.; Springhorn, K. F.; Tiffin, P. D. SC 1992, 22, 1967.
7. Cardillo, G.; Orena, M.; Sandri, S. TL 1976, 44, 3985.
8. (a) Angyal, S. J. OR 1954, 8, 197 (Chapter 4). (b) Bla&zbreve;ević, N.; Kolbah, D.; Belin, B.; &SSbreve;unjić, V.; Kajfe&zbreve;, F. S 1979, 161.
9. (a) Koyama, Y.; Huang, S-P.; Ikeda, D.; Kondo, S. Synlett 1990, 389. (b) Tanaka, H.; Taniguchi, M.; Kameyama, Y.; Yamaguchi, T.; Sasaoka, M.; Shiroi, T.; Torii, S. Synlett 1990, 660. (c) Kilenyi, S. N. COS, 1991, 7, 653. (d) Larock, R. C. Comprehensive Organic Transformations; VCH: New York, 1989; pp 599-600.
10. Ref. 9d, pp 591-593.

William Berkowitz

City University of New York, Flushing, NY, USA

Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.