Regioselective Peroxidation of Dienes
1
2.96 (t, J ) 7.0 Hz, 2 H), 4.35 (t, J ) 7.0 Hz, 2 H), 7.20-7.29
(m, 5 H), 8.64 (s, 1 H); 13C NMR δ 24.5 (2 C), 34.9, 43.1 (t, J
) 19.3 Hz), 65.3, 81.0, 126.5, 128.4 (2 C), 128.6 (2 C), 137.3,
171.3.
(from ether-hexane); H NMR δ 0.81 (s, 3 H), 1.05 (s, 3 H),
1.28 (s, 3 H), 1.33 (s, 3 H), 1.35 (dd, J ) 13.1, 2.4 Hz, 1 H),
1.76 (s, 3H), 2.03 (t, J ) 13.1 Hz, 1 H), 4.62 (dd, J ) 13.1, 2.4
Hz, 1 H), 7.2-7.3 (m, 5 H), 7.90 (s, 1 H); 13C NMR δ 20.2 (CH3),
20.8 (CH3), 20.9 (CH3), 24.2 (CH3), 26.3 (CH3), 35.7 (C), 35.8
(CH2), 81.6 (CH), 83.3 (C), 86.7 (C), 126.0 (CH, 2 C), 126.8 (CH),
127.4 (CH, 2 C), 141.6 (C). Anal. Calcd for C16H24O4: C, 68.54;
H, 8.63. Found: C, 68.32; H, 8.43.
2-(5,5-Dimethyl-1,2-dioxolan-3-yl)propan-2-ol (26d): oil;
1H NMR δ 1.14 (s, 3 H), 1.27 (s, 3 H), 1.34 (s, 6 H), 2.08 (s, 1
H; H-D exchange in D2O), 2.33 (dd, J ) 12.0 and 7.6 Hz, 1
H), 2.40 (dd, J ) 12.0, 7.6 Hz, 1 H) 4.13 (t, J ) 7.6 Hz, 1 H);
13C NMR δ 24.4, 25.0, 26.0, 27.2, 46.8, 71.8, 83.8, 87.1.
6-Methyl-2-phenyl-5-hepten-2-yl Hydroperoxide (24a):
oil; 1H NMR δ 1.53 (s, 3 H), 1.66 (s, 6 H), 1.79-1.97 (m, 4 H),
5.06-5.09 (m, 1 H), 7.26-7.45 (m, 5 H); 13C NMR δ 17.7, 22.6,
22.8, 25.7, 39.5, 86.2, 123.8, 125.5 (2 C), 127.2, 128.4 (2 C),
132.1, 143.8.
Peroxidation of Alkene 8 with Co(acac)2 and Et3SiD
in EtOH. Reaction of 3-butenyl benzoate (8, 360 mg, 2.0 mmol)
with Co(acac)2 (27 mg, 0.10 mmol) and triethylsilane-d (480
mg, 4.1 mmol) in 5 mL of EtOH was conducted according to
general procedure, and the reaction mixture was stirred for 2
h. The conventional workup afforded a mixture of alkene 8
and the corresponding triethylsilyl peroxide 18-d, which was
eluted with diethyl ether-hexane (3:97). After treatment of
this mixture with a drop of concentrated HCl, followed by
workup similar to that described in the general procedure,
products were separated by column chromatography on silica
gel. 3-Butenyl benzoate (8, 60 mg) was recovered by elution
with diethyl ether-hexane (3:97) (conversion ) 83%). Subse-
quent elution with diethyl ether-hexane (15:85) gave 4-deu-
terio-3-hydroperoxybutyl benzoate (300 mg, 84%).
4-Deuterio-3-hydroperoxybutyl Benzoate (18-d): oil;
1H NMR δ 1.30 (dt, J ) 6.2 and 1.8 Hz, 2 H), 1.89-2.18 (m, 2
H), 4.28 (quintet, J ) 6.2 Hz, 1 H), 4.42-4.47 (m, 2 H), 7.39-
7.44 (m, 2 H), 7.51-7.57 (m, 1H), 8.00-8.04 (m, 2 H), 9.10-
9.12 (m, 1 H); 13C NMR δ 18.1 (t, J ) 19.3 Hz), 31.1, 61.9,
78.3, 128.2 (2 C), 129.3 (2 C), 129.8, 132.9, 166.8.
General Procedure for Peroxidation of Dienes with
Co(modp)2. Reaction of 3,3,6-trimethyl-2-phenyl-1,5-hepta-
diene (19d) is representative. Into a two-neck, 50 mL flask
charged with dioxygen were added the diene 19d (428 mg, 2.0
mmol), Co(modp)2 (53 mg, 0.098 mmol), and DCE (5.0 mL),
and then the flask was again charged with dioxygen. Triethyl-
silane (460 mg, 4.0 mmol) was added via 1.0 mL gastight
syringe, and the reaction mixture was stirred vigorously under
an oxygen atmosphere at room temperature. After the mixture
was stirred for 3 h, the solvent was evaporated under reduced
pressure. Hexane (10 mL) was added to the residue, and then
the precipitated solid materials were removed by filtration over
Celite. After concentration of the filtrate, the components of
the residue were separated by column chromatography on
silica gel. Elution with diethyl ether-hexane (5:95) gave a
mixture of diene 19d and the triethylsilyl peroxide 21d (320
mg). Subsequent elution with diethyl ether-hexane (7:93) gave
epoxide 23d (240 mg), which was contaminated with small
amount of impurities. Acetophenone 22 (103 mg, 51%) was
obtained by elution with diethyl ether-hexane (10:90).
The first fraction, a mixture of diene 19d and the triethyl-
silyl peroxide 21d, was dissolved in MeOH (1.0 mL) and
treated with one portion of concentrated HCl. After the
mixture was stirred for 1 min, solid NaHCO3 and MgSO4 were
added. The reaction mixture was stirred for an additional 5
min, and solid materials were removed by filtration over Celite.
After concentration of the filtrate under reduced pressure,
products were separated by column chromatography on silica
gel. The diene 19d (70 mg) was recovered by elution with
diethyl ether-hexane (5:95) (conversion ) 84%). Elution with
diethyl ether-hexane (15:85) gave 2-(5,5,6-trimethyl-6-phenyl-
1,2-dioxan-3-yl)propan-2-yl hydroperoxide (25d, 146 mg, 31%).
Desilylation of epoxide 23, eluted by diethyl ether-hexane
(7:93), was conducted in the same way as described for the
treatment of the first fraction. Product was isolated by column
chromatography on silica gel. Elution with diethyl ether-
hexane (40:60) gave 2-(5,5-dimethyl-1,2-dioxolan-3-yl)propan-
2-ol (26d, 69 mg, 26%).
6-Methyl-2-phenyl-5-hepten-2-ol:35 oil; 1H NMR δ 1.47 (s,
3 H), 1.54 (s, 3 H), 1.63 (s, 3 H), 1.81-1.97 (m, 5 H), 5.04-
5.10 (m, 1H), 7.20-7.44 (m, 5 H); 13C NMR δ 17.7, 23.0 (2 C),
25.8, 30.6, 75.0, 124.0, 124.7 (2 C), 126.3, 128.0 (2 C), 132.1,
147.7.
2-(6-Methyl-6-phenyl-1,2-dioxan-3-yl)propan-2-yl Hy-
droperoxide (25a): oil (ca. 2:1 mixture of two stereoisomers);
1H NMR δ 1.04 (s, 1 H), 1.12 (s, 1 H), 1.30 (s, 2 H, major), 1.32
(s, 2 H, major), 1.36 (s, 1 H), 1.63 (s, 2 H, major), 1.70-2.20
(m, 3.67 H), 2.58 (dt, J ) 13.9, 3.5 Hz, 0.33 H), 4.24 (dd, J )
9.8, 4.0 Hz, 0.67 H, major), 4.32 (dd, J ) 9.8, 4.0 Hz, 0.33 H),
7.24-7.47 (m, 5 H), 7.60 (s, 0.33 H), 8.08 (s, 0.67 H); 13C NMR
δ 20.4 (CH2, major), 20.8 (CH3), 20.9 (CH3), 21.0 (CH3), 23.8
(CH3), 30.0 (CH3), 33.0 (CH2), 33.4 (CH2, major), 81.6 (C,
major), 82.7 (C), 83.1 (C), 83.3 (C, major), 84.5 (CH, major),
84.6 (CH), 124.5 (CH), 125.7 (CH), 126.8 (CH), 127.4 (CH),
128.3 (CH), 143.3 (C), 145.2 (C). Anal. Calcd for C14H20O4: C,
66.65; H, 7.99. Found: C, 66.48; H, 8.03.
3,6-Dimethyl-2-phenyl-5-hepten-2-yl Hydroperoxide
(24b): oil (3:1 mixture of two stereoisomers); H NMR δ 0.64
1
(d, J ) 6.6 Hz, 0.75 H), 0.94 (d, J ) 7.3 Hz, 2.25 H, major),
1.39 (s, 2.25 H, major), 1.58 (s, 1.5 H), 1.61 (s, 2.25 H, major),
1.67 (s, 2.25 H, major), 1.68 (s, 0.75 H), 1.40-1.90 (m, 2.75
H), 2.30-2.40 (m, 0.25 H), 4.91-4.97 (m, 0.75 H, major), 5.00-
5.10 (m, 0.25 H), 7.09-7.46 (m, 6 H); 13C NMR δ 14.1 (major),
14.8, 17.5, 17.6 (major), 17.7 (major), 17.9, 25.8 (major), 25.9,
29.7, 30.4 (major), 43.0 (major), 43.2, 89.0 (major), 89.2, 122.8
(major), 123.2, 126.1, 126.3 (major), 127.2, 127.3 (major), 128.3
(major), 132.5 (major), 143.2 (major). Anal. Calcd for C15H22O2:
C, 76.88; H, 9.46. Found: C, 76.59; H, 9.48.
1-(5,6-Dimethyl-6-phenyl-1,2-dioxan-3-yl)propan-2-yl
Hydroperoxide (25b): oil (1:1 mixture of two stereoisomers);
1H NMR δ 0.83 (d, J ) 6.9 Hz, 1.5 H), 0.99 (br d, J ) 7.7 Hz,
1.5 H), 1.10-1.80 (m, 2 H), 1.23 (s, 1.5 H), 1.27 (s, 1.5 H), 1.30
(s, 1.5 H), 1.36 (s, 1.5 H), 1.58 (s, 1.5 H), 1.66 (s, 1.5 H), 2.10-
2.35 (m, 1 H), 4.38 (t, J ) 7.4 Hz, 0.5 H), 4.49-4.55 (m, 0.5
H), 7.23-7.57 (m, 5 H), 7.91 (br s, 0.5 H), 8.03 (br s, 0.5 H);
13C NMR δ 20.9, 21.0, 21.1 (2 C), 29.5, 38.8, 83.3, 85.3, 85.7,
126.1, 127.0, 127.7, 128.0. Anal. Calcd for C15H22O4: C, 67.64;
H, 8.33. Found: C, 67.51; H, 8.54.
1-(5-Methyl-1,2-dioxolan-3-yl)propan-2-ol (26b): oil (ca.
1:1 mixture of two mixtures); H NMR δ 1.16-1.32 (m, 9 H),
1
2.06 (s, 0.5 H), 2.13 (s, 0.5 H), 2.16-2.29 (m, 1 H), 2.62-2.78
(m, 1 H), 4.10-4.18 (m, 1 H), 4.34-4.46 (m, 1 H); 13C NMR δ
16.4 (CH3), 18.5 (CH3), 24.7 (CH3), 25.3 (CH3), 26.9 (CH3), 27.0
(CH3), 42.2 (CH2), 42.3 (CH2), 70.9 (C), 71.4 (C), 77.7 (CH),
77.9 (CH), 86.5 (CH) 87.1 (CH). Anal. Calcd for C7H14O3: C,
57.51; H, 9.65. Found: C, 57.83; H, 9.50.
[2-Methyl-1-(3,3-dimethyloxiran-2-yl)propan-2-yl]tri-
1
ethylsilane (23d): oil; H NMR δ 0.69 (q, J ) 7.9 Hz, 6 H),
0.98 (t, J ) 7.9 Hz, 9 H), 1.27 (s, 3 H), 1.28 (s, 3 H), 1.29 (s, 3
H), 1.33 (s, 3 H), 1.70 (dd, J ) 14.6, 5.7 Hz, 1 H), 1.93 (dd, J
) 14.6, 5.7 Hz, 1 H), 2.90 (t, J ) 5.7 Hz, 1 H); 13C NMR δ 3.9
(CH2, 3 C), 6.9 (CH3, 3 C), 19.1 (CH3), 24.2 (CH3), 24.9 (CH3),
25.2 (CH3), 37.8 (CH2), 57.7 (C), 61.0 (CH), 81.6 (C).
[2-(3,3-Dimethyloxiran-2-yl)-1-phenylethylperoxy]tri-
1
ethylsilane (23c): oil (1:1 mixture of two stereoisomers); H
NMR δ 0.63-0.70 (m, 6 H), 0.91-0.97 (m, 9 H), 1.09 (s, 1.5
2-(5,5,6-Trimethyl-6-phenyl-1,2-dioxan-3-yl)propan-2-
yl Hydroperoxide (25d): colorless solid, mp 115-116 °C
(35) Sundarababu, B.; Imadul, I.; Srinivasan, C. J. Org. Chem. 1990,
55, 891.
J. Org. Chem, Vol. 70, No. 1, 2005 259