Dalton Transactions
Paper
All products have been previously described, and 1H, 13C NMR,
and IR data are in accordance with literature data.
Table 1 Complex 1 catalyzed allylic oxidation of olefins
Synthetic procedures
Synthesis of 6-N-3,5-di-tert-butylsalicylidene-6,7-quinoxali-
nol-diamine Cu(II) complex 1. The ligand was synthesized in
accordance with a previously published procedure.1 In a
100 mL round-bottomed flask charged with a stirring bar,
0.20 mmol of ligand (89.6 mg) and 0.24 mmol of
Cu(OAc)2·H2O were dissolved with 20 mL of dichloromethane
and 20 mL of methanol. After 1.2 mmol of triethylamine was
added, the reaction was stirred for 2 h at reflux temperature.
After solvent was removed, the resulting dark red solid was
washed with water and cold ether 3 times each. A product of
93.2 mg of solid was obtained (82%). HRMS was obtained
from high yields of these microcrystalline samples inappropri-
ate for characterization by X-ray diffraction.
6-N-3,5-Di-tert-butylsalicylidene-6,7-quinoxalinol-diamine Cu(II)
complex 1. UV-Vis (CHCl3): 334 nm (ε = 9000 M−1 cm−1).
Formula (M + H): C29H39N4O4Cu. HRMS: found 571.2351
(M + H), calcd 571.2346 (M + H).
Representative procedure for allylic oxidation of olefins
using complex 1. To a 50 mL round-bottomed flask charged
Entry
1
Substrate
Product
Time (h)
1
Isolated yield (%)
96
2
3
1
2
85
72
4
5
3
1
96
91
6
3
89
with
a
stirring bar, were sequentially added complex
7
8
1
2
75
1 (2.5 μmol), CH3CN (10 mL), 1-acetyl-1-cyclohexene (0.5 mmol),
and t-BuOOH (1.5 mmol). After the reaction was stirred at 70 °C
for 1 h, solvent was removed under reduced pressure. The
residue was purified by flash column chromatography with
hexane–ethyl acetate as eluent to yield product as yellowish oil.
3-Acetyl-2-cyclohexenone (entry 1, Table 1). 1H NMR: δ 6.58
(bs, 1 H), 2.50 (m, 2 H), 2.48 (m, 2 H), 2.41 (s, 3 H), 2.00
(m, 2 H). 13C NMR: δ 201.5, 200.1, 154.6, 132.5, 37.9, 26.2, 23.4,
21.9. Formula: C8H10O2. HRMS: found 138.0687, calcd 138.0681.
3-Phenyl-2-cyclohexenone (entry 2, Table 1). 1H NMR:
δ 7.55–7.53 (m, 2 H), 7.42–7.41 (m, 3H), 6.43 (t, J = 1.2 Hz,
1 H), 2.78 (m, 2 H), 2.49 (t, J = 6.0 Hz, 2 H), 2.18–2.13 (m, 2 H).
13C NMR: δ 200.0, 159.9, 139.0, 130.0, 128.8, 126.1, 125.5, 37.3,
28.1, 22.8. Formula: C12H12O. HRMS: found 172.0881, calcd
172.0888.
54a
10a
60
9
2
a Yield as found by gas chromatography (GC).
3-Acetoxy-2-cyclohexenone (entry 3, Table 1). 1H NMR:
27.6, 22.0. Formula: C7H7NO. HRMS: found 121.0525, calcd
δ 5.92 (s, 1 H), 2.54 (t, J = 6.8 Hz, 2 H), 2.42 (t, J = 6.4 Hz, 2 H), 121.0528.
2.23 (s, 3 H), 2.09 (m, 2 H). 13C NMR: δ 200.0, 170.0, 167.4,
117.5, 36.6, 28.3, 21.2, 21.2. Formula: C8H10O3. HRMS: found
154.0626, calcd 154.0630.
3-Methyl-2-cyclohexenone (entry 7, Table 1). 1H NMR: δ 5.87
(d, J = 1.6 Hz, 1 H), 2.33 (t, J = 6.4 Hz, 1 H), 2.31–2.28 (m, 2 H),
2.02–1.98 (m, 2 H), 1.96 (s, 3 H). 13C NMR: δ 199.6, 162.8,
3-Acetyl-2-cyclopentenone (entry 4, Table 1). 1H NMR: δ 6.67 126.5, 36.8, 30.8, 24.4, 22.5. Formula: C7H10O. HRMS: found
110.0725, calcd 110.0732.
(t, J = 2.0 Hz, 1 H), 2.83–2.80 (m, 2 H), 2.56–2.51 (m, 2 H), 2.50
(s, 3 H). 13C NMR: δ 210.6, 197.3, 169.3, 137.0, 35.4, 27.8, 26.3.
Formula: C7H8O2. HRMS: found 124.0520, calcd 124.0524.
4-Cyclopentene-1,3-dione monoethylene ketal (entry 5,
5-Methyl-2-cyclohexenone (entry 8, Table 1). 1H NMR:
δ 6.98–6.94 (m, 1 H), 6.03–6.00 (m, 1 H), 2.51–2.39 (m, 2 H),
2.27–2.17 (m, 1 H), 2.15–1.99 (m, 2 H), 1.07 (d, J = 6.4 Hz, 3 H).
Table 1). 1H NMR: δ 7.20 (d, J = 6.0 Hz, 1 H), 6.19 (d, J = 13C NMR: δ 200.1, 149.3, 129.6, 46.2, 34.0, 30.3, 21.2. Formula:
6.0 Hz, 1 H), 4.03 (m, 4 H), 2.60 (s, 2 H). 13C NMR: δ 204.0, C7H10O. HRMS: found 110.0722, calcd 110.0732.
5-tert-Butyl-2-cyclohexenone (entry 9, Table 1). 1H NMR:
156.3, 135.4, 111.6, 65.2, 45.2. Formula: C7H8O3. HRMS: found
140.0465, calcd 140.0473.
3-Cyano-2-cyclohexenone (entry 6, Table 1). 1H NMR: δ 6.52 2.17–2.08 (m, 2 H), 1.89–1.82 (m, 1 H), 0.92 (s, 9 H). 13C NMR:
δ 201.1, 150.8, 129.2, 45.2, 40.0, 32.3, 27.5, 26.9. Formula:
2 H). 2.13 (m, 2 H). 13C NMR: δ 196.6, 138.6, 131.1, 117.0, 37.2, C10H16O. HRMS: found 152.1192, calcd 152.1201.
δ 7.05–7.00 (m, 1 H), 6.04–6.01 (m, 1 H), 2.56–2.38 (m, 2 H),
(s, 1 H), 2.57 (dt, J = 6.0 Hz, 2.0 Hz, 2 H), 2.54 (t, J = 6.2 Hz,
This journal is © The Royal Society of Chemistry 2014
Dalton Trans., 2014, 43, 13578–13583 | 13579