4-MeC6H4I-Mediated
Efficient α-Tosyloxylation of Ketones with Oxone® and p-Toluenesulfonic Acid in Acetonitrile

Ayumi Tanaka; Hideo Togo

doi:10.1055/s-0029-1218370

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Synlett 2009(20): 3360-3364
DOI: 10.1055/s-0029-1218370

LETTER

4-MeC₆H₄I-Mediated Efficient α-Tosyloxylation of Ketones with Oxone^® and p-Toluenesulfonic Acid in Acetonitrile

Ayumi Tanaka, 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 25 September 2009
Publikationsdatum:
27. November 2009 (online)

Abstract
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Abstract

Various alkyl aryl ketones, dialkyl ketones, and cycloheptanone were efficiently converted into the corresponding α-tosyloxy ketones in good yields by using Oxone^® and p-toluenesulfonic acid monohydrate in the presence of p-iodotoluene in acetonitrile. 4-Methoxyacetophenone and 2-acetylthiophene bearing an electron-rich aromatic group could be also converted into the corresponding α-tosyloxyketones smoothly in good yields with the present method. Here, p-iodotoluene works as catalyst and p-[(hydroxy)(tosyloxy)]iodotoluene is formed in situ as a reactive species for the α-tosyloxylation of ketones. However, one equivalent of p-iodotoluene was required to obtain α-tosyloxyketones in good yields and was recovered in 80-20% yields, depending on the reaction conditions.

Key words

p-iodotoluene - Oxone^® - α-tosyloxyketone - ketone - p-toluenesulfonic acid - catalyst

References and Notes

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8

Typical Procedure for 4-MeC ₆ H ₄ I-Mediated α-Tosyloxylation of Ketone with Oxone ^® and
p -Toluenesulfonic Acid Monohydrate To a solution of acetophenone (120 mg, 1 mmol) in MeCN (4 mL) were added p-iodotoluene (218 mg, 1.0 mmol), PTSA˙H₂O (951 mg, 5 mmol), and Oxone^® (249 mg, 1.5 mmol). The mixture was stirred for 5 h at 60 ˚C under an argon atmosphere. After the reaction, the reaction mixture was poured into sat. aq NaHCO₃ solution and extracted with CHCl₃ (3 × 20 mL). The organic layer was dried over Na₂SO₄. After removal of the solvent under reduced pressure, α-tosyloxyacetophenone was obtained as a crude state. Pure α-tosyloxyacetophenone was obtained in 94% yield by short flash column chromatography on silica gel (EtOAc-hexane = 1:4).
α-Tosyloxyacetophenone Mp 90 ˚C (lit.^³h 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 105 ˚C (lit.⁹ 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.⁹ 125 ˚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.⁹ 130-131 ˚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.⁹ 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), 7.59 (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).
α-(Tosyloxy)octyl Phenyl Ketone Mp 59-61 ˚C (lit.^4d 59-61 ˚C). IR (neat): 1180, 1340, 1700 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 0.86 (t, J = 6.9 Hz, 3 H), 1.20-1.43 (m, 10 H), 1.84-1.91 (m, 2 H), 2.40 (s, 3 H), 5.59 (dd, J = 8.2, 4.8 Hz, 1 H), 7.24 (d, J = 8.0 Hz, 2 H), 7.45 (t, J = 7.5 Hz, 2 H), 7.59 (t, J = 7.5 Hz, 1 H), 7.74 (d, J = 8.2 Hz, 2 H), 7.86 (d, J = 8.2 Hz, 2 H). α-Tosyloxy-3-pentanone Mp 45-46 ˚C (lit.^³k 43-44 ˚C). IR (neat): 1190, 1360, 1720 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 1.03 (t, J = 7.3 Hz, 3 H), 1.35 (d, J = 7.0 Hz, 3 H), 2.47 (s, 3 H), 2.60 (m, 2 H), 4.80 (q, J = 7.0 Hz, 1 H), 7.37 (d, J = 8.0 Hz, 2 H), 7.81 (d, J = 8.0 Hz, 2 H).
α-Tosyloxy-6-undecanone Mp 72 ˚C (lit.^4d 72 ˚C). IR (neat): 1190, 1380, 1720 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 0.70-0.80 (m, 3 H), 0.86-1.75 (m, 15 H), 2.46 (s, 3 H), 2.51 (t, J = 7.5 Hz, 2 H), 4.64 (dd, J = 8.0, 4.6 Hz, 1 H), 7.36 (d, J = 8.0 Hz, 2 H), 7.80 (d, J = 8.0 Hz, 2 H). α-Tosyloxycycloheptanone
Oil. IR (neat): 1190, 1590, 1720 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 1.48-1.95 (m, 8 H), 2.42-2.63 (m, 5 H), 4.98 (t, J = 5.1 Hz, 1 H), 7.35 (d, J = 8.0 Hz, 2 H), 7.83 (d, J = 8.0 Hz, 2 H). ^¹³C NMR (400 MHz, CDCl₃): δ = 21.36, 22.30, 24.77, 27.45, 30.93, 39.98, 83.75, 127.61, 129.51, 133.00, 144.66, 206.05. HRMS-FAB: m/z calcd for C₁₄H₁₉O₄S [M + 1]: 283.1004; found: 283.0986.
Methyl α-Tosyloxyacetoacetate Oil. IR (neat): 1180, 1320, 1720 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 2.30 (s, 3 H), 2.48 (s, 3 H), 3.71 (s, 3 H), 5.20 (s, 1 H), 7.38 (d, J = 8.5 Hz, 2 H), 7.83 (d, J = 8.5 Hz, 2 H). ^¹³C NMR(400 MHz, CDCl₃): δ = 21.66, 26.53, 53.27, 80.34, 128.18, 129.98, 132.02, 145.90, 163.86, 196.98. HRMS-FAB: m/z calcd for C₁₂H₁₅O₆S [M + 1]: 287.0589; found: 287.0596.
Ethyl α-Tosyloxybenzoylacetate Oil. IR (neat): 1440, 1590, 1690 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 1.18 (t, J = 7.0 Hz, 3 H), 2.85 (s, 3 H), 4.18 (m, 2 H), 5.59 (s, 1 H), 7.30 (d, J = 8.4 Hz, 2 H), 7.46 (t, J = 7.5 Hz, 2 H), 7.61 (t, J = 7.5 Hz, 1 H), 7.79 (d, J = 8.5 Hz, 2 H), 7.93 (d, J = 8.5 Hz, 2 H). ^¹³C NMR (400 MHz, CDCl₃): δ = 13.75, 21.63, 62.80, 78.03, 128.24, 128.71, 129.34, 129.82, 132.34, 133.28, 134.36, 145.68, 164.12, 188.19. HRMS-FAB: m/z calcd for C₁₈H₁₉O₆S [M + 1]: 363.0902; found: 363.0920.
1-Tosyloxy-2-octanone Oil. IR (neat): 1180, 1360, 1590,1730 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 0.87 (t, J = 7.0 Hz, 3 H), 1.20-1.32 (m, 6 H), 1.48-1.62 (m, 2 H), 2.45 (s, 3 H), 2.49 (t, J = 7.2 Hz, 2 H), 4.49 (s, 2 H), 7.37 (d, J = 8.0 Hz, 2 H), 7.82 (d, J = 8.0 Hz, 2 H). ^¹³C NMR (400 MHz, CDCl₃): δ = 13.97, 21.68, 22.39, 22.76, 28.62, 31.43, 38.98, 71.78, 128.04, 130.00, 132.30, 145.44, 203.43. HRMS-FAB: m/z calcd for C₁₅H₂₃O₄S [M + 1]: 299.1317; found: 299.1295.

3-Tosyloxy-2-octanone Oil. IR (neat): 1180, 1360, 1600, 1740 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 0.80 (t, J = 7.3 Hz, 3 H), 1.00-1.30 (m, 6 H), 1.54-1.78 (m, 2 H), 2.23 (s, 3 H), 2.48 (s, 3 H), 4.58 (dd, J = 8.4, 4.6 Hz, 1 H), 7.36 (d, J = 8.7 Hz, 2 H), 7.81 (d, J = 8.7 Hz, 2 H). ^¹³C NMR (400 MHz, CDCl₃): δ = 13.91, 21.97, 22.35, 24.17, 26.01, 31.00, 31.52, 84.62, 128.13, 130.07. 132.98, 145.48, 205.78. HRMS-FAB: m/z calcd for C₁₅H₂₃O₄S [M + 1]: 299.1317; found: 299.1315.
2-Thienyl (Tosyloxy)methyl Ketone Mp 92-93 ˚C (lit.^³i 94-96 ˚C). IR (KBr): 1685, 1370, 1180, 730 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 2.45 (s, 3 H), 5.09 (s, 2 H), 7.16 (dd, J = 5.0, 3.9 Hz, 1 H), 7.35 (d, J = 8.1 Hz, 2 H), 7.73 (dd, J = 5.0, 1.0 Hz, 1 H), 7.79 (dd, J = 3.9, 1.0 Hz, 1 H), 7.85 (d, J = 8.1 Hz, 2 H).
α-Tosyloxy- p -methoxyacetophenone Mp 131-132 ˚C. IR (KBr): 1684, 1376, 1171 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 2.45 (s, 3 H), 3.88 (s, 3 H), 5.20 (s, 2 H), 6.93 (d, J = 8.5 Hz, 2 H), 7.34 (d, J = 8.8 Hz, 2 H), 7.83 (d, J = 8.8 Hz, 2 H), 7.85 (d, J = 8.5 Hz, 2 H). ^¹³C NMR (400 MHz, CDCl₃): δ = 30.89, 55.55, 69.77, 114.11, 125.88, 128.15, 129.87, 130.43, 133.52, 144.70, 163.52, 189.17. ESI-HRMS: m/z calcd for C₁₆H₁₆O₅SNa [M + Na]: 343.0611; found: 343.0602.
α-Tosyloxy- m -nitroacetophenone Mp 129-130 ˚C. IR (KBr): 1615, 1375, 1348, 1188 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 2.46 (s, 3 H), 5.25 (s, 2 H), 7.37 (d, J = 8.0 Hz, 2 H), 7.72 (t, J = 8.0 Hz, 1 H), 7.84 (d, J = 8.0 Hz, 2 H), 8.21 (dt, J = 8.0, 1.2 Hz, 1 H), 8.46 (dt, J = 8.0, 1.2 Hz, 1 H), 8.63 (t, J = 1.2 Hz, 1 H). ^¹³C NMR (400 MHz, CDCl₃): δ = 30.38, 69.87, 123.05, 128.15, 128.25, 130.03, 130.25, 132.35, 133.72, 135.29, 144.70, 145.88, 188.82. ESI-HRMS: m/z calcd for C₁₅H₁₃O₆NSNa [M + Na]: 358.0356; found: 358.0347.
2,4,6-Trimethylphenyl (Tosyloxy)methyl Ketone Mp 58 ˚C. IR (neat): 1191, 1377, 1608 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 2.12 (s, 6 H), 2.27 (s, 3 H), 2.45 (s, 3 H), 4.84 (s, 2 H), 6.81 (s, 2 H), 7.33 (d, J = 8.0 Hz, 2 H), 7.87 (d, J = 8.0 Hz, 2 H). ^¹³C NMR (400 MHz, CDCl₃): δ = 18.96, 21.08, 21.65, 72.28, 128.05, 128.61. 129.81, 132.70, 133.83, 134.70, 139.82, 145.19, 201.17. Elemental Analysis: Calcd for C₁₈H₂₀O₄S. C 65.04, H 6.06%. Found: C 64.70, H 5.90%.
2-Furyl (Tosyloxy)methyl Ketone Mp 63-64 ˚C (lit.^³h 65-67 ˚C). IR (KBr): 1695, 1370, 1170, 810, 750 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 2.45 (s, 3 H), 5.09 (s, 2 H), 6.58 (dd, J = 3.7, 1.7 Hz, 1 H), 7.33 (dd, J = 3.7, 0.7 Hz, 1 H), 7.36 (d, J = 8.2 Hz, 2 H), 7.61 (dd, J = 1.7, 0.7 Hz, 1 H), 7.86 (d, J = 8.2 Hz, 2 H).
α-( p -Chlorobenzenesulfonyloxy)acetophenone Mp 96 ˚C (lit.^¹0 97 ˚C). IR (KBr): 1180, 1540, 1700 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 5.36 (s, 2 H), 7.48 (t, J = 7.5 Hz, 2 H), 7.56 (d, J = 8.9 Hz, 2 H), 7.63 (t, J = 8.9 Hz, 1 H), 7.84 (d, J = 7.5 Hz, 2 H), 7.92 (d, J = 8.9 Hz, 2 H).
α-(Camphorsulfonyloxy)acetophenone Oil (lit.^¹¹ 60-61 ˚C). IR (neat): 1170, 1590, 1720 cm^-¹. ^¹H NMR (400 MHz, CDCl₃): δ = 0.92 (s, 3 H), 1.14 (s, 3 H), 1.42-1.51 (m, 1 H), 1.74-1.85 (m, 1 H), 1.95 (d, J = 18.6 Hz, 1 H), 2.04-2.16 (m, 2 H), 2.36-2.55 (m, 2 H), 3.35 (d, J = 15.3 Hz, 1 H), 3.82 (d, J = 15.3 Hz, 1 H), 5.53 (s, 2 H), 7.52 (t, J = 7.2 Hz, 2 H), 7.64 (t, J = 7.2 Hz, 1 H), 7.92 (d, J = 7.2 Hz, 2 H).