PAPER
Oxidation of Anilines with Hydrogen Peroxide and Selenium Dioxide as Catalyst
1893
For the scaled-up reaction, the crude product was purified by col-
umn chromatography on silica gel (CH2Cl2–hexane, 1:3).
dried in a desiccator over Sicacide®. The crude product was purified
by column chromatography on silica gel (CH2Cl2–pentane, 2:3).
Yield: 3.92 g (83%); mp 200 °C; Rf = 0.39 (CH2Cl2).
Yield: 297 mg (76%); orange-yellow needles; mp 191 °C; Rf = 0.32
(CH2Cl2–pentane, 2:3).
IR (ATR): 3107, 3005, 2957, 2852, 1709, 1464, 1276, 1111, 857,
771, 688 cm–1.
1H NMR (400 MHz, CDCl3): d = 3.95 (s, 3 H), 3.97 (s, 3 H), 8.14–
8.21 (m, 6 H), 8.37–8.40 (m, 2 H).
13C NMR (100 MHz, CDCl3): d = 52.3, 52.6, 122.5, 125.3, 130.2,
130.4, 130.7, 133.3, 146.9, 150.9, 165.7, 166.2.
HRMS: m/z [M]+ calcd for C16H14N2O5: 314.0902; found:
314.0902.
IR (ATR): 3078, 1531, 1523, 1480, 1468, 1346, 1320, 863, 753, 684
cm–1.
1H NMR (400 MHz, CDCl3): d = 8.28–8.32 (m, 2 H), 8.36–8.39 (m,
2 H), 8.41–8.44 (m, 2 H), 8.52–8.56 (m, 2 H).
13C NMR (100 MHz, CDCl3): d = 123.8, 124.4, 124.5, 126.3, 147.4,
147.8, 149.9, 151.3.
HRMS: m/z [M]+ calcd for C12H8N4O5: 288.0495; found: 288.0491.
Bis(4-bromophenyl)diazene Oxide (6d)35
Bis(4-ethylphenyl)diazene Oxide (6h)38
The crude product was purified by column chromatography on sili-
ca gel (CH2Cl2–pentane, 1:10).
After complete consumption of the starting material, H2O was add-
ed and the precipitate was separated, washed with H2O and dried in
a desiccator over Sicacide®. The crude product was purified by col-
umn chromatography on silica gel (CH2Cl2–pentane, 1:6) to give
6d.
Yield: 251 mg (67%); yellow oil; Rf = 0.60 (CH2Cl2–pentane, 1:7).
IR (ATR): 3076, 3031, 2966, 2932, 2873, 1603, 1499, 1462, 839
cm–1.
1H NMR (400 MHz, CDCl3): d = 1.27–1.35 (m, 6 H), 2.70–2.77 (m,
4 H), 7.29–7.36 (m, 4 H), 8.24–8.29 (m, 4 H).
13C NMR (100 MHz, CDCl3): d = 15.00, 15.04, 28.3, 28.6, 122.0,
125.6, 127.77, 127.80, 141.9, 145.9, 146.1, 147.8.
HRMS: m/z [M]+ calcd for C16H18N2O: 254.1419; found: 254.1425.
Yield: 440 mg (83%); yellow glittering flakes; mp 171 °C; Rf = 0.39
(CH2Cl2–pentane, 1:6).
IR (ATR): 3097, 3057, 3028, 1478, 1461, 1073, 1009, 826 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.58–7.65 (m, 4 H), 8.05–8.09 (m,
2 H), 8.15–8.18 (m, 2 H).
13C NMR (100 MHz, CDCl3): d = 123.6, 123.9, 126.5, 127.2,
131.98, 132.04, 142.6, 147.0.
4-Methoxy-N-(4-nitrophenyl)aniline (7i)39
The crude product was purified by column chromatography on sili-
ca gel (CH2Cl2–pentane, 1:1).
HRMS: m/z [M]+ calcd for C12H8N2OBr2: 355.8977; found:
355.8983.
Yield: 194 mg (50%); orange-red needles; mp 144 °C; Rf = 0.61
(CH2Cl2).
1H NMR (400 MHz, CDCl3): d = 3.83 (s, 3 H), 6.15 (br s, 1 H),
6.74–6.78 (m, 2 H), 6.91–6.95 (m, 2 H), 7.14–7.18 (m, 2 H), 8.05–
8.09 (m, 2 H).
Bis(4-chlorophenyl)diazene Oxide (6e)35
The crude product was purified by column chromatography on sili-
ca gel (CH2Cl2–pentane, 1:6).
Yield: 328 mg (82%); yellow solid.
For the scaled-up reaction, the crude product was purified by col-
umn chromatography on silica gel (CH2Cl2–hexane, 1:6).
13C NMR (100 MHz, CDCl3): d = 55.5, 112.6, 114.9, 125.5, 126.3,
132.0, 139.1, 151.7, 157.4.
Yield: 3.66 g (91%); mp 153 °C; Rf = 0.47 (CH2Cl2–pentane, 1:6).
IR (ATR): 3062, 1482, 1464, 829 cm–1.
HRMS: m/z [M]+ calcd for C13H12N2O3: 244.0847; found:
244.0848.
1H NMR (400 MHz, CDCl3): d = 7.43–7.50 (m, 4 H), 8.14–8.18 (m,
4-Ethoxy-N-(4-nitrophenyl)aniline (7j)40
The crude product was purified by column chromatography on sili-
ca gel (CH2Cl2–hexane, 1:1).
2 H), 8.23–8.27 (m, 2 H).
13C NMR (100 MHz, CDCl3): d = 123.7, 127.1, 128.97, 129.03,
135.2, 138.1, 142.2, 146.5.
HRMS: m/z [M]+ calcd for C12H8N2OCl2: 266.0014; found:
266.0017.
Yield: 125 mg (32%); orange solid; mp 128 °C; Rf = 0.32 (CH2Cl2–
hexane, 2:1).
IR (ATR): 3352, 3073, 3042, 2980, 2921, 2851, 2414, 1594, 1508,
1477, 1392, 1322, 1303, 1242, 1183, 1111 cm–1.
1H NMR (400 MHz, CDCl3): d = 1.43 (t, J = 7.0 Hz, 3 H), 4.05 (q,
J = 7.0 Hz, 2 H), 6.14 (br s, 1 H), 6.74–6.78 (m, 2 H), 6.90–6.94 (m,
2 H), 7.12–7.16 (m, 2 H), 8.06–810 (m, 2 H).
13C NMR (100 MHz, CDCl3): d = 14.8, 63.8, 112.6, 115.5, 125.5,
126.3, 131.8, 139.0, 151.7, 156.8.
Bis(4-cyanophenyl)diazene Oxide (6f)36
The crude product was purified by column chromatography on sili-
ca gel (CH2Cl2–pentane, 1:1).
Yield: 312 mg (84%); yellow solid; mp 221 °C; Rf = 0.60 (CH2Cl2).
IR (ATR): 3075, 3044, 2234, 2224, 1491, 1461, 843 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.78–7.81 (m, 2 H), 7.85–7.88 (m,
2 H), 8.21–8.24 (m, 2 H), 8.44–8.48 (m, 2 H).
13C NMR (100 MHz, CDCl3): d = 113.1, 116.1, 117.3, 118.2, 123.4,
126.0, 132.8, 133.1, 146.3, 150.2.
HRMS: m/z [M]+ calcd for C14H14N2O3: 258.1004; found:
258.1004.
Acknowledgment
HRMS: m/z [M]+ calcd for C14H8N4O: 248.0698; found: 248.0698.
The authors acknowledge support from the Cluster of Exellence
‘Unifying Concepts in Catalysis’ coordinated by the Technische
Universität Berlin and funded by the Deutsche Forschungsgemein-
schaft, and the Fonds der Chemischen Industrie.
Bis(4-nitrophenyl)diazene Oxide (6g)37
After complete consumption of the starting material (TLC), H2O
was added and the precipitate was separated, washed with H2O and
Synthesis 2008, No. 12, 1889–1894 © Thieme Stuttgart · New York