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The Journal of Organic Chemistry
0.220 mmol), and triethylsilane (0.530 mL, 3.30 mmol) in DCE
2877, 1726, 1168, 1006, 863, 730 cm-1; HRMS (APCI) m/z calcd
for C11H24KO4Si (M + K)+ 287.1075, found 287.1067.
(1.0 mL). The reaction time was 2.5 h. CDCl3 (0.70 mL) was added
and the crude reaction mixture was transferred to an NMR tube fol-
lowed by mesitylene (0.031 mL, 0.220 mmol, internal standard).
The yield of lactone 9 and carboxylic acid 11 was determined based
on 1H NMR spectroscopic analysis of the area of the internal stand-
ard (δ 6.77) and the area of the methine group of lactone 9 (δ 4.81)
and carboxylic acid 11 (δ 8.16). Purification by flash chromatog-
raphy (hexane:EtOAc = 75:25 → hexane:EtOAc = 50:50) afforded
an analytical sample of carboxylic acid 11 (0.004 g, 10%) as a white
solid. The spectroscopic data are consistent with the data re-
ported:48 1H NMR (600 MHz, DMSO) δ 8.14 (d, J = 8.0, 2H), 7.88
(d, J = 8.1, 2H); 13C NMR (150 MHz, DMSO) δ 166.2, 134.9, 132.3
(q, J = 31.6), 130.1, 125.6, 124.7 (q, J = 272.2); IR (ATR) 3312,
1762 cm-1.
Silyl peroxide 14. Silyl peroxide 14 was prepared using the rep-
resentative procedure for the Co-catalyzed oxygenation of aromatic
compounds using 2-methylfuran (13, 0.080 mL, 0.914 mmol),
Co(acac)2 (0.012 g, 0.046 mmol), tert-butyl hydroperoxide (0.046
mL, 0.046 mmol), acetylacetone (0.093 mL, 0.914 mmol), and tri-
ethylsilane (2.19 mL, 13.7 mmol) in DCE (4.2 mL). The reaction
time was 2 h. Purification by flash chromatography (hexane:EtOAc
= 95:5) afforded silyl peroxide 14 as a colorless oil (0.015 g, 4%):
1H NMR (600 MHz, CDCl3) δ 4.44 (m, 1H), 4.34 (dd, J = 12.1, 3.8,
1H), 4.27 (dd, J = 12.1, 5.7, 1H), 4.20 (dd, J = 12.1, 5.6, 1H), 4.08
(dd, J = 12.1, 4.9, 1H), 2.08 (s, 3H), 0.98 (m, 18H), 0.70 (m, 12H);
13C NMR (150 MHz, CDCl3) δ 171.0 (C), 80.8 (CH), 74.4 (CH2),
62.2 (CH2), 21.0 (CH3), 6.85 (CH3), 6.84 (CH3), 3.81 (CH2), 3.79
(CH2); IR (ATR) 2958, 2878, 1747, 1236, 849, 740 cm-1; HRMS
(APCI) m/z calcd for C17H39O6Si2 (M + H)+ 395.2279, found
395.2277.
1
2
3
4
5
6
7
8
Lactone 21 and Silyl peroxide 22. Lactone 21 and silyl perox-
ide 22 were prepared using the representative procedure for the Co-
catalyzed oxygenation of aromatic compounds using ethyl 3-fu-
roate (20, 0.096 mL, 0.714 mmol), Co(acac)2 (0.009 g, 0.036
mmol), tert-butyl hydroperoxide (0.036 mL, 0.036 mmol), acety-
lacetone (0.073 mL, 0.714 mmol), and triethylsilane (1.71 mL, 10.7
mmol) in DCE (3.2 mL). The reaction time was 2.5 h. Purification
by flash chromatography (hexane:EtOAc = 95:5) afforded lactone
21 as a colorless oil (0.037 g, 17%) and silyl peroxide 22 as a col-
orless oil (0.044 g, 14%). Lactone 21: 1H NMR (600 MHz, CDCl3)
δ 4.58 (d, J = 10.9, 1H), 4.53 (d, J = 10.9, 1H), 4.27 (q, J = 7.2,
2H), 3.04 (d, J = 18.5, 1H), 2.90 (d, J = 18.6, 1H), 1.31 (t, J = 7.2,
3H), 0.96 (t, J = 8.0, 9H), 0.68 (q, J = 7.9, 6H); 13C NMR (150
MHz, CDCl3) δ 173.4 (C), 168.4 (C), 87.9 (C), 71.7 (CH2), 62.5
(CH2), 36.3 (CH2), 14.2 (CH3), 6.7 (CH3), 3.7 (CH2); IR (ATR)
2957, 1794, 1743, 1310, 1030, 803, 742 cm-1; HRMS (APCI) m/z
calcd for C13H25O6Si (M + H)+ 305.1415, found 305.1417. Silyl
peroxide 22: 1H NMR (600 MHz, CDCl3) δ 8.08 (s, 1H), 4.81 (d,
J = 12.0, 1H), 4.62 (d, J = 12.1, 1H), 4.32 (d, J = 12.0, 1H), 4.22
(m, 2H), 4.17 (d, J = 12.0, 1H), 1.29 (t, J = 7.2, 3H), 0.95 (t, J =
8.1, 18H), 0.66 (m, 12H); 13C NMR (150 MHz, CDCl3) δ 168.6
(C), 160.7 (CH), 85.6 (C), 74.0 (CH2), 61.6 (CH2), 60.6 (CH2), 14.2
(CH3), 6.77 (CH3), 6.73 (CH3), 3.79 (CH2), 3.73 (CH2); IR (ATR)
2956, 2878, 1735, 1172, 1019, 847, 733 cm-1; HRMS (APCI) m/z
calcd for C19H44NO8Si2 (M + NH4)+ 470.2600, found 470.2600.
Silyl peroxide 24. Silyl peroxide 24 was prepared using the rep-
resentative procedure for the Co-catalyzed oxygenation of aromatic
compounds using benzofuran 23 (0.090 mL, 0.847 mmol),
Co(acac)2 (0.011 g, 0.042 mmol), tert-butyl hydroperoxide (0.042
mL, 0.042 mmol), and triethylsilane (0.676 mL, 4.23 mmol) in
DCE (3.8 mL). The reaction time was 6 h. Purification by flash
chromatography (pentane → pentane:Et2O = 95:5) afforded silyl
peroxide 24 (0.099 g, 44%) as a colorless oil: 1H NMR (600 MHz,
CDCl3) δ 7.43 (d, J = 7.2, 1H), 7.30 (t, J = 7.8, 1H), 6.93 (t, J = 7.2,
1H), 6.89 (d, J = 7.8, 1H), 5.61 (dd, J = 6.0, 1.8, 1H), 4.78 (dd, J =
11.4, 2.0, 1H), 4.47 (dd, J = 11.1, 6.0, 1H), 0.99, (t, J = 7.8, 9H),
0.70 (q, J = 7.8, 6H); 13C NMR (150 MHz, CDCl3) δ 161.8 (C),
131.6 (CH), 127.3 (CH), 123.5 (C), 120.7 (CH), 110.7 (CH), 84.9
(CH), 75.4 (CH2), 6.9 (CH3), 3.9 (CH2); IR (ATR) 2954, 2877,
1612, 1600, 1479, 1246, 1015, 963, 832 cm-1; HRMS (APCI) m/z
calcd for C14H21O2Si (M + H – H2O)+ 249.1305, found 249.1306.
Dione 26. Dione 26 was prepared using the representative pro-
cedure for the Co-catalyzed oxygenation of aromatic compounds
using isobenzofuran 25 (0.050 g, 0.185 mmol), Co(acac)2 (0.002 g,
0.009 mmol), tert-butyl hydroperoxide (0.009 mL, 0.009 mmol),
and triethylsilane (0.440 mL, 2.78 mmol) in DCE (1.7 mL). The
reaction time was 18 h. Following the workup as described above,
dione 26 isolated as a white, off-yellow solid (0.041 g, 78%). Char-
acterization was performed without further purification. The spec-
troscopic data are consistent with the data reported:49 mp 130–133
°C, which is lower than reported literature value (138–139 °C)49
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10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Bis(silylperoxide) 16 and 17. Bis(silylperoxides) 16 and 17
were prepared using the representative procedure for the Co-cata-
lyzed oxygenation of aromatic compounds using 2-benzylfuran
(15, 0.055 g, 0.348 mmol), Co(acac)2 (0.005 g, 0.017 mmol), tert-
butyl hydroperoxide (0.017 mL, 0.017 mmol), acetylacetone (0.036
mL, 0.348 mmol), and triethylsilane (0.833 mL, 5.22 mmol) in
DCE (1.6 mL). The reaction time was 2.5 h. Purification by flash
chromatography (hexane → hexane:EtOAc = 98:2) afforded bis(si-
lylperoxides) 16 and 17 as an inseparable 59:41 mixture of diastere-
1
omers: H NMR (600 MHz, CDCl3) δ 7.32–7.21 (m, 8.5H), 4.75
(m, 0.6H), 4.43 (m, 1H), 4.17 (d, J = 9.8, 0.7H), 4.13 (dd, J = 9.8,
4.4, 0.7H), 4.09 (dd, J = 9.6, 6.4, 1H), 4.00 (dd, J = 9.7, 4.9, 1H),
3.25 (d, J = 10.6, 0.7H), 3.23 (d, J = 10.5, 1H), 3.15 (d, J = 13.9,
1H), 2.27 (dd, J = 15.0, 7.2, 0.7H), 2.08 (dd, J = 15.0, 8.1, 1H),
1.96 (m, 1.7H), 1.05–0.93 (m, 36.9H), 0.80–0.62 (m, 24.6H); 13C
NMR (150 MHz, CDCl3) δ 136.9 (C), 136.6 (C), 130.74 (CH),
130.71 (CH), 128.2 (CH), 128.1 (CH), 126.69 (CH), 126.66 (CH),
114.6 (C), 114.0 (C), 85.3 (CH), 83.7 (CH), 72.7 (CH2), 71.9 (CH2),
42.2 (CH2), 40.9 (CH2), 37.5 (CH2), 37.2 (CH2), 6.93 (CH3), 6.91
(CH3), 6.90 (CH3), 6.84 (CH3), 4.04 (CH2), 3.99 (CH2), 3.89 (CH2),
3.80 (CH2); IR (ATR) 2954, 2877, 1456, 1239, 1006, 803, 740, 701
cm-1; HRMS (APCI) m/z calcd for C23H46NO5Si2 (M + NH4)+
472.2909, found 472.2904.
1
due to residual impurities; H NMR (600 MHz, CDCl3) δ 7.72 (d,
Silyl peroxide 19. Silyl peroxide 19 was prepared using the rep-
resentative procedure for the Co-catalyzed oxygenation of aromatic
compounds using pyran 18 (0.054 mL, 0.594 mmol), Co(acac)2
(0.008 g, 0.030 mmol), tert-butyl hydroperoxide (0.030 mL, 0.030
mmol), acetylacetone (0.061 mL, 0.594 mmol), and triethylsilane
(1.42 mL, 8.92 mmol) in DCE (2.7 mL). The reaction time was 2
h. Purification by flash chromatography (hexane:EtOAc = 95:5) af-
forded silyl peroxide 19 as a colorless oil (0.038 g, 26%): 1H NMR
(600 MHz, CDCl3) δ 8.05 (s, 1H), 4.18 (t, J = 6.3, 2H), 4.00 (t, J =
6.1, 2H), 1.73 (m, 4H), 0.99 (t, J = 8.0, 9H), 0.69 (q, J = 7.9, 6H);
13C NMR (150 MHz, CDCl3) δ 161.3 (CH), 76.3 (CH2), 63.9 (CH2),
25.5 (CH2), 24.6 (CH2), 6.9 (CH3), 3.9 (CH2); IR (ATR) 2955,
J = 1.2, 2H), 7.70 (d, J = 1.1, 2H), 7.63 (d, J = 1.1, 4H), 7.53 (m,
2H), 7.39 (m, 4H); 13C NMR (150 MHz, CDCl3) δ 196.8 (C), 140.2
(C), 137.4 (C), 133.2 (CH), 130.6 (CH), 130.0 (CH), 129.9 (CH),
128.5 (CH); IR (ATR) 1659, 1596, 1278, 937, 704 cm-1; HRMS
(ESI) m/z calcd for C20H14NaO2 (M + Na)+ 309.0886, found
309.0898.
Lactam 28 and Bis(silylperoxy) ketone 29. Lactam 28 and
bis(silyl peroxy) ketone 29 were prepared using the representative
procedure for the Co-catalyzed oxygenation of aromatic com-
pounds using pyrrole 27 (0.100 g, 0.380 mmol), Co(acac)2 (0.020
g, 0.076 mmol), tert-butyl hydroperoxide (0.019 mL, 0.019 mmol),
acetylacetone (0.039 mL, 0.380 mmol), and triethylsilane (0.909
mL, 5.70 mmol) in DCE (1.7 mL). The reaction time was 2.5 h.
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