Ethyldiphenylsulfonium Tetrafluoroborate1

[893-69-6]  · C14H15BF4S  · Ethyldiphenylsulfonium Tetrafluoroborate  · (MW 302.17)

(transformation of carbonyl groups to oxiranes;2 a,b-unsaturated systems to a-cyclopropyl ketones;3 a very powerful alkylating agent4)

Physical Data: mp 76-77 °C.

Form Supplied in: not commercially available.

Preparative Methods: there are two common methods of preparation. The first involves adding Silver(I) Tetrafluoroborate to a solution of Ph2S and Ethyl Iodide (5 equiv), and stirring the mixture for several hours (eq 1).5

The second method is a relatively new and unique technique.6 Under acidic conditions, the alkylation of aliphatic and aromatic sulfides has been carried out by using alcohols instead of alkyl halides (eq 2).

Carbonyl Additions to Form Oxiranes.

To a solution of ethyldiphenylsulfonium tetrafluoroborate in THF at -76 °C under nitrogen was added an appropriate alkyllithium, followed by 0.9 equiv of cyclohexanone. After stirring for 1 h and workup, the oxirane shown (eq 3) was obtained in good yield.7

Reactions with a,b-Unsaturated Carbonyl Groups.

If the carbonyl group is a,b-unsaturated, reaction takes place at the alkene to form substituted cyclopropanes.8 Meyers et al. have taken advantage of this and used ethyldiphenylsulfonium tetrafluoroborate to form 1,2,3-trisubstituted cyclopropanes (eq 4).3

O-Alkylation of Carboxylates and Amides.

Ethyldiphenylsulfonium tetrafluoroborate acts as a very powerful alkylating agent and converts phosphoric diesters to phosphoric triesters (eq 5).9 Ethyldiphenylsulfonium tetrafluoroborate also performs O-alkylation of amides10 and carboxylate salts.11

1. Trost, B. M.; Melvin L. S., Jr. In Sulfur Ylides: Emerging Synthetic Intermediates; Academic: New York, 1975.
2. Lescure, P.; Huet, F. S 1987, 404.
3. Meyers, A. I.; Romo, D. JOC 1992, 57, 6265.
4. Badet B.; Julia, M.; Ramirez-Muñzo, M. S 1980, 926.
5. Franzen, V.; Schmidt, H. J.; Mertz, C. CB 1961, 94, 2942.
6. Badet, B.; Julia, M. TL 1979, 1101.
7. Corey, E. J.; Oppolzer, W. JACS 1964, 86, 1899.
8. Corey, E. J.; Jautelat, M. JACS 1967, 89, 3912.
9. Badet, B.; Julia, M.; Rolando, C. S 1982, 291.
10. Julia, M.; Mestdagh, H. T 1983, 39, 433.
11. Badet, B.; Julia, M.; Ramirez-Muñoz, M.; Sarrazin, C. A. T 1983, 39, 3111.

Tony Durst & Robert N. Ben

University of Ottawa, Ontario, Canada

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