PAPER
Catalytic IBX Oxidation
259
13C NMR (CDCl3): d = 23.8, 28.8, 28.9, 29.0, 29.2, 29.8, 33.7, 43.7,
COOH
I
n-Bu4N+HSO5
–
114.1, 139.0, 209.1.
HRMS (ESI): m/z calcd for C11H20O [M + Na]+: 191.14064; found:
191.14069.
–
n-Bu4N+HSO5
Dodec-11-en-2-one (9)
1H NMR (CDCl3): d = 1.19–1.56 (m, 10 H), 1.95–2.42 (m, 7 H),
2.38 (t, 2 H, J = 7.3 Hz), 4.87–5.00 (m, 2 H), 5.67–5.87 (m, 1 H).
13C NMR (CDCl3): d = 23.8, 28.8, 29.0, 29.1, 29.2, 29.3, 29.8, 33.7,
43.7, 114.0, 139.0, 209.2.
O
O
HRMS (ESI): m/z calcd for C12H22O [M + H]+: 183.17434; found:
183.17436.
O
O
I
I
OH
O
OH
Undec-10-enoic Acid (12)
1H NMR (CDCl3): d = 1.22–1.64 (m, 10 H), 2.01–2.34 (m, 6 H),
4.89–5.03 (m, 2 H), 5.67–5.87 (m, 1 H).
13C NMR (CDCl3): d = 14.3, 22.8, 24.8, 29.0, 29.2, 29.3, 29.4, 31.7,
37.8, 114.3, 139.3, 179.9.
RCH2OH
RR'CHOH
O
HRMS (ESI): m/z calcd for C11H19O2 [M – H]+: 183.13905; found:
183.13980.
R
R'
n-Bu4N+HSO5
–
RCHO
RCOOH
Acknowledgment
Scheme 1 Catalytic cycle for the oxidation of alcohols with IBX.
A. Schulze gratefully acknowledges Graduiertenkolleg ‘Mechani-
stische und Anwendungsaspekte nicht-konventioneller Oxidations-
reaktionen’ for grants. We are also grateful to Fonds der
chemischen Industrie for financial support.
tion of alcohols.22 For these transformations, only
catalytic amounts of IBX or 2-iodobenzoic acid in combi-
nation with Oxone are used.
References
Reagents (except for IBX4a) and solvents were commercially avail-
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1
able and were used without further purification. H and 13C NMR
1
spectra were recorded on a Varian Gemini 200 (200 MHz for H
NMR; 50 MHz for 13C NMR), Varian Gemini 2000 (200 MHz for
1H NMR; 50 MHz for 13C NMR) and Varian Gemini 300 (300 MHz
1
for H NMR; 75.5 MHz for 13C NMR) in CDCl3. Chemical shifts
are relative to the residual solvent peak, which was used as an inter-
nal reference. HRMS was obtained on a Bruker Daltonics APEX II
(for ESI). The progress of the reaction was monitored on a Varian
SATURN 2200 GC-MS. Flash column chromatography was per-
formed on Merck silica gel 60 (0.040–0.063 mm). Spectral data of
benzaldehyde (1),12 4-nitrobenzaldehyde (3),12 2-isopropyl-5-meth-
ylcyclohexanone (6),12 dec-9-enoic acid (11)20 and 3,7-dimethyloc-
tanoic acid (14)21 were consistent with those reported previously.
The identity of 3-fluorobenzaldehyde (2), cyclododecanone (4), cy-
clohexanone (5), acetophenone (7), octanoic acid (10) and 6-chlo-
rohexanoic acid (13) was ascertained by NMR spectroscopy and by
comparison with an authentic sample.
Oxidation with IBX or 2-Iodobenzoic Acid; Typical Procedure
To a solution of the alcohol (1 mmol) in EtOAc (2 mL), Oxone
(1 mmol), IBX or 2-iodobenzoic acid (0.1 mmol), n-Bu4NHSO4
(0.1 mmol) and finally H2O (0.5 mL) were added. The reaction
mixture was stirred at 70 °C for 4–7 h depending on the alcohol. Af-
ter completion of the reaction, the mixture was diluted with H2O
(10 mL) and EtOAc (10 mL) and the layers were separated. The
aqueous layer was extracted with EtOAc (3 × 10 mL) and the com-
bined organic layers were dried over Na2SO4. The solvent was re-
moved under reduced pressure to give the desired product.
Analytically pure products were obtained after column chromatog-
raphy.
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Undec-10-en-2-one (8)
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1H NMR (CDCl3): d = 1.27–1.61 (m, 10 H), 1.95–2.10 (m, 5 H),
2.39 (t, 2 H, J = 7.3 Hz), 4.86–5.00 (m, 2 H), 5.67–5.87 (m, 1 H).
Synthesis 2006, No. 2, 257–260 © Thieme Stuttgart · New York