On Aromatic Electrophilic Substitution Promoted by In Situ Generated Thionium Ions

Abstract

α-Sulfanylated α-arylacetates and -thioacetates were prepared via ethylthiomethylation reaction of aromatic compounds. These aromatic electrophilic substitutions were performed by in situ generation of the thionium ions by reacting trifluoroacetic anhydride and S-ethyl 2-(ethylsulfinyl)ethanethioate or ethyl 2-(ethylsulfinyl)acetate in the presence of Lewis acids. Some mechanistic features of these ethylthiomethylation reactions are also presented.

Key words

ethylthiomethylation - Pummerer reaction - sulfoxide - aromatic electrophilic substitution

• References

• 1 Feldman KS. Tetrahedron 2006; 62: 5003
• 2 Akai S, Kita Y. Top. Curr. Chem. 2007; 274: 35
• 3 Smith LH. S, Coote SC, Sneddon HF, Procter DJ. Angew. Chem. Int. Ed. 2010; 49: 5832
• 4 Bur SK, Padwa A. Chem. Rev. 2004; 104: 2401
• 5 Bates DK. J. Org. Chem. 1977; 42: 3452
• 6a Stamos IK. Tetrahedron Lett. 1985; 26: 477
• 6b Stamos IK. Tetrahedron Lett. 1985; 26: 2787
• 7 Trost BM. Chem. Rev. 1978; 78: 363
• 8 Wladislaw B, Marzorati L, Gruber J. Phosphorus, Sulfur Silicon Relat. Elem. 1990; 47: 21
• 9 Kenney WJ, Walsh JA, Davenport DA. J. Am. Chem. Soc. 1961; 83: 4019
• 10 Walker D, Leib J. Can. J. Chem. 1962; 40: 1242
• 11 Tamura Y, Choi HD, Shindo H, Uenishi J, Ishibashi H. Tetrahedron Lett. 1981; 22: 81

Isolated from the crude product by crystallization. Physical constants and spectroscopic data agree with those reported in the literature for the same compound:
• 12a Durkin KA, Langler RF, Morrison NA. Can. J. Chem. 1988; 66: 3070

This product could originate from a putative sulfoxonium ion:
• 12b Annunziata R, Cinquini M, Colonna S. J. Chem. Soc., Perkin Trans. 1 1975; 282
• 13 Wladislaw B, Marzorati L, Di Vitta C. Phosphorus, Sulfur Silicon Relat. Elem. 1991; 62: 225
• 14 Perrin DD, Armarego WL. F, Perrin DR. Purification of Laboratory Chemicals . Pergamon Press; Oxford: 1996
• 15 Purvis JE, Jones HO, Tasker HS. J. Chem. Soc. 1910; 97: 2287
• 16 Ogura K, Yahata N, Watanabe J. Bull. Chem. Soc. Jpn. 1983; 56: 3543
• 17 Identical GC/MS data were obtained for one of two components of the crude mixture for the reaction of sulfoxide 1 and benzene, in the presence of TFAA and BF₃·Et₂O. This component was identified as 7 on the basis of the methine ¹H NMR signal as reported for the same compound: Ando W, Suzuki J, Arai T, Migita T. Tetrahedron 1973; 29: 1507
• 18 Takeuchi Y, Asahina N, Hori K, Koizumi T. J. Chem. Soc., Perkin Trans. 1 1988; 1149
• 19 Lecher H, Holschneider F. Ber. Deutsch. Chem. Ges. B 1924; 57: 87
• 20a Oae S, Takata T, Kim YH. Tetrahedron 1981; 37: 37
• 20b Oae S, Takata T, Kim YH. Bull. Chem. Soc. Jpn. 1982; 55: 2484
• 21 Brintzinger H, Pfannstiel K, Koddebusch H, Kling KE. Chem. Ber. 1950; 83: 87