Synlett 2007(14): 2168-2172  
DOI: 10.1055/s-2007-984914
LETTER
© Georg Thieme Verlag Stuttgart · New York

Efficient Conversion of Ketones to α-Tosyloxyketones with m-Chloroperbenzoic Acid and p-Toluenesulfonic Acid in the Presence of Catalytic Amount of IL-Supported PhI in [emim]OTs

Junnosuke Akiike, Yukiharu Yamamoto, Hideo Togo*
Graduate School of Science, Chiba University, Yayoi-cho 1-33, Inage-ku, Chiba 263-8522, Japan
e-Mail: togo@faculty.chiba-u.jp;
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Publikationsverlauf

Received 14 June 2007
Publikationsdatum:
20. Juli 2007 (online)

Abstract

Various ketones were smoothly converted into the corresponding α-tosyloxyketones with MCPBA and p-toluenesulfonic acid in the presence of a catalytic amount of ionic-liquid (IL)-supported PhI in room temperature ionic liquid, [emim]OTs. Moreover, the present ionic-liquid reaction media containing a catalytic amount of IL-supported PhI could be reused for the same α-tosyl­oxylation of ketones and thiazoles directly, keeping good yields.

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α-Tosyloxyketones
α-Tosyloxyacetophenone Mp 90 °C (lit.2h 90-91 °C). IR (KBr): 1180, 1360, 1715 cm-1. 1H NMR (400 MHz, CDCl3): δ = 2.45 (s, 3 H), 5.27 (s, 2 H), 7.35 (d, J = 8.5 Hz, 2 H), 7.47 (t, J = 8.2 Hz, 2 H), 7.61 (t, J = 8.2 Hz, 1 H), 7.84 (d, J = 8.2 Hz, 2 H), 7.85 (d, J = 8.2 Hz, 2 H). α-Tosyloxy- p -methylacetophenone Mp 80 °C (lit.24 82-83 °C). IR (KBr): 1170, 1350, 1700 cm-1. 1H NMR (400 MHz, CDCl3): δ = 2.41 (s, 3 H), 2.45 (s, 3 H), 5.24 (s, 2 H), 7.26 (d, J = 8.1 Hz, 2 H), 7.35 (d, J = 8.2 Hz, 2 H), 7.74 (d, J = 8.1 Hz, 2 H), 7.86 (d, J = 8.2 Hz, 2 H). α-Tosyloxy- p -chloroacetophenone
Mp 123 °C (lit.24 125 °C). IR (KBr): 1190, 1360, 1710 cm-1. 1H NMR (400 MHz, CDCl3): δ = 2.46 (s, 3 H), 5.21 (s, 2 H), 7.35 (d, J = 8.4 Hz, 2 H), 7.45 (d, J = 8.6 Hz, 2 H), 7.80 (d, J = 8.6 Hz, 2 H), 7.84 (d, J = 8.4 Hz, 2 H).
α-Tosyloxy- p -nitroacetophenone Mp 137 °C (lit.24 130-131 °C). IR (KBr): 1180, 1340, 1710 cm-1. 1H NMR (400 MHz, CDCl3): δ = 2.47 (s, 3 H), 5.25 (s, 2 H), 7.37 (d, J = 8.3 Hz, 2 H), 7.83 (d, J = 8.3 Hz, 2 H), 8.03 (d, J = 8.9 Hz, 2 H), 8.32 (d, J = 8.9 Hz, 2 H).
α-Tosyloxypropiophenone Mp 68 °C (Lit.24 68-69 °C). IR (KBr): 1170, 1370, 1700 cm-1. 1H NMR (400 MHz, CDCl3): δ = 1.60 (d, J = 7.0 Hz, 3 H), 2.41 (s, 3 H), 5.79 (q, J = 7.0 Hz, 1 H), 7.29 (d, J = 8.1 Hz, 2 H), 7.46 (t, J = 7.2 Hz, 2 H), 7.60 (t, J = 7.2 Hz, 1 H), 7.75 (d, J = 7.2 Hz, 2 H), 7.88 (d, J = 8.1 Hz, 2 H).
Thiazoles
2-Methyl-4-phenylthiazole
Mp 64 °C (lit.25 67 °C). IR (KBr): 1600 cm-1. 1H NMR (400 MHz, CDCl3): δ = 2.78 (s, 3 H), 7.31 (s, 1 H), 7.32 (t, J = 7.5 Hz, 1 H), 7.41 (t, J = 7.5 Hz, 2 H), 7.87 (d, J = 7.5 Hz, 2 H).
2,4-Diphenylthiazole
Mp 167 °C (lit.26 168 °C). IR (KBr): 1600 cm-1. 1H NMR (400 MHz, CDCl3): δ = 7.27 (t, J = 7.5 Hz, 1 H), 7.35-7.45 (m, 6 H), 7.75 (m, 2 H), 8.05 (d, J = 6.8 Hz, 2 H).