Oxidation of alkenes by oxodiperoxomolybdenum: Trialkyl(aryl)phosphine oxide complexes

Article abstract of DOI:10.1055/s-2006-958933

Catalytic amounts of short-chain (2-4 carbons) trialkylphosphine oxide ligands and MoO₅ have been shown to efficiently convert di- and higher substituted alkenes to the corresponding epoxides using a biphasic system with either 30% hydrogen peroxide or 70% TBHP acting as the stoichiometric oxidant. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2006-958933

92
PAPER
Oxidation of Alkenes by Oxodiperoxomolybdenum: Trialkyl(aryl)phosphine
Oxide Complexes
T
rialkyl(aryl)pho
h
sphine
O
xide
r
Compl
iexes stine I. Altinis Kiraz, Luis Mora, Leslie S. Jimenez*
Department of Chemistry & Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, NJ
08854-8087, USA
E-mail: Jimenez@rutchem.rutgers.edu
Received 25 August 2006
Table 1 Stoichiometric Epoxidation of Cyclooctene with Com-
Abstract: Catalytic amounts of short-chain (2–4 carbons) trialkyl-
plexes 1–5
phosphine oxide ligands and MoO5 have been shown to efficiently
convert di- and higher substituted alkenes to the corresponding ep-
oxides using a biphasic system with either 30% hydrogen peroxide
or 70% TBHP acting as the stoichiometric oxidant.
MoO5⋅R3PO⋅L
O
CH2Cl2, r.t.
Keywords: epoxidations, organometallic reagents, heterogenous
catalysis, molybdenum complexes, green chemistry
Oxidant
MoO5·R3PO·L
Reaction
time
Isolated Yield (%)
(% NMR conversion)a
R = Me, L = MeOH (1)
R = Et, L = MeOH (2)
48 h
40 min
3 h
46 (>99)
50 (>99)
60 (90)
58 (96)
31 (96)
Epoxides provide useful intermediates in the synthesis of
various natural products and organic materials. Both in
homogeneous and heterogeneous catalysis, complexes of R = n-Pr, L = H2O (3)
many transition metals including Ti, W, Ru, V, Re, Mn,
R = n-Bu, L = n-Bu3PO (4)
12 h
12 h
Cr, Rh, and Mo have been utilized in delivering oxygen to
alkenes.1 Moreover, diperoxo complexes of group 5,2
R = Ph, L = Ph3PO (5)
group 6,3 and group 74 elements have been the focus of re-
a Estimated yields through comparison of NMR integration values of
the corresponding epoxides and alkenes.
cent research for potential industrial use as oxidants.
We recently reported the synthesis of a series of oxodiper-
oxomolybdenum·trialkylphosphine oxide (Mimoun-
type)5 complexes which oxidize indoles to a variety of
products depending on the substitution pattern at carbons
2 and 3.6 We report here both the stoichiometric and cata-
lytic epoxidation of several representative alkenes with
the oxodiperoxomolybdenum·trialkyl(aryl)phosphine ox-
ide complexes 1–5.
dation to ketones or epoxide opening to form diols was
observed with any of the complexes.
Once the most active oxidants were identified, stoichio-
metric oxidations were performed on other alkenes to fur-
ther elucidate the activity of these complexes (Table 2).
Oxidations of terpenes such as a-pinene led to formation
of rearranged products; several aldehyde peaks were visi-
ble by 1H NMR spectroscopy. It is well known that com-
plete transformation of terminal alkenes lacking electron-
donating substituents to epoxides is difficult.8 Not surpris-
ingly, when terminal alkenes were subjected to stoichio-
metric oxidation conditions with 2 or 3 only 40–60%
conversions were observed over several days. Results of a
Density Functional Theory (DFT) study on factors that ef-
fect reactivity in epoxidations with Mimoun complexes
indicates that the activation barrier to epoxidation can be
significantly reduced with incorporation of electron-do-
nating substituents on the alkene double bond.9
A stoichiometric reaction was performed with cyclo-
octene to identify the most active complex in the epoxida-
tion of this alkene. The reactions were performed at room
temperature in anhydrous dichloromethane under an at-
mosphere of nitrogen and with equimolar amounts of cy-
clooctene and oxidant (Table 1). Isolated yields were
moderate due to the volatility of cyclooctene oxide, but
conversion of the alkene to epoxide as measured by inte-
gration of the NMR peaks of the starting substrate and
product7 were high to essentially complete.
The results indicate that complex 2 is the most active ox-
idant as conversion to the epoxide is achieved within 40
minutes. Conversely, oxidant 1 utilizing trimethylphos-
phine oxide as ligand required 48 hours to form cy-
clooctene oxide due to low solubility of this complex in
organic solvents. The rest of the coordinatively saturated
complexes formed the epoxide exclusively; no over-oxi-
In stoichiometric oxidations, it was found that due to their
enhanced solubilities in dichloromethane, both 2 and 3
transfer oxygen efficiently to form epoxides with the ex-
ception of terpenes and allylbenzene where formation of
aldehydes was observed. As expected, 7-methylocta-1,6-
diene forms the monoepoxide exclusively at the more
electron-rich, trisubstituted double bond rather than at the
terminal alkene. In general, greater yields of epoxides re-
sult with substituted electron-rich alkenes compared to
electron-poor terminal alkenes with oxidants 2 or 3.
SYNTHESIS 2007, No. 1, pp 0092–0096
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x
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x
x
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0
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Advanced online publication: 12.12.2006
DOI: 10.1055/s-2006-958933; Art ID: M05606SS
© Georg Thieme Verlag Stuttgart · New York

PAPER
Trialkyl(aryl)phosphine Oxide Complexes
93
Table 2 Stoichiometric Oxidation of Alkenes with 2/3
Table 3 Catalytic Oxidation of Alkenes using Catalytic Amounts of
MoO5 and R3PO with H2O2 as the Stoichiometric Oxidant (Method 1)
Alkene
MoO5·R3PO·L Time Epoxide yield (%)
(h) (% NMR conversion)a
MoO5 (5 mol%), 30% H2O2 (3–4 equiv)
alkene
epoxide
R3PO (10–15 mol%), CHCl3
oct-1-ene
3
2
2
2
3
2
3
2
2
3
2
24
1
(37)
Alkene
R3PO
Temp Time Isolated yield (%)
a-pinene
other products
other products
50 (60)
(°C)
(h)
(% NMRconversion)
allylbenzene
30
72
24
16
48
24
72
96
96
cyclooctenea
cyclooctene
cyclooctene
cyclooctene
cyclooctene
allylbenzenea
R = Me
R = Et
60
18
(12)
dodec-1-ene
45–55 23
95 (>99)
90
cyclododecene
cyclododecene
7-methylocta-1,6-diene
7-methylocta-1,6-diene
trans-dec-5-ene
trans-dec-5-ene
4-phenylbut-1-ene
63 (>99)
(>99)
R = n-Pr
40
20
18
24
R = n-Bu 55
95 (>99)
81 (90)
(60)
49% (>99)
(>99)
R = Ph
R = Et
R = Ph
55
60–70 12
40–55 24
85 (97)
7-methylocta-
1,6-diene
70
91 (>99)
(45)
7-methylocta-
1,6-diene
R = Et
40
70
18
18
95 (>99)
a Estimated yields through comparison of NMR integration values of
the corresponding epoxide and alkene peaks.
cyclododecene
R = n-Pr
94 (>99)
(87)
trans-dec-5-enea R = Ph
trans-dec-5-ene R = n-Pr
a Product not isolated.
65–70 16
65–70 16
The surfactant-mediated biphasic protocol established by
Sundermeyer et al.10 catalytically epoxidizes alkenes uti-
lizing H2O2 as the stoichiometric oxidant and catalytic
amounts of various long-chain trialkylphosphine oxides
as ligands for the Mimoun complexes. We developed a
modified procedure in which catalytic amounts of a MoO5
stock solution,11 short-chain trialkylphosphine oxide
ligand, and 3–4 equivalents of 30% H2O2 were combined
with the alkene substrate, and heated in chloroform. The
results of these biphasic oxidations are summarized in
Table 3. Trialkylphosphine oxides with alkyl chain
lengths of 2–4 carbons seemed to execute the oxidation in
a reasonable time and yield, providing full conversion into
the epoxide with no trace of the starting material as ob-
served by 1H NMR. For the Ph3PO ligand, a 90% conver-
60 (68)
1
sion was observed by H NMR spectroscopy. Thus,
moderate to excellent yields of epoxides can be obtained
under biphasic conditions using the environmentally-
friendly hydrogen peroxide (reduced by-product = water)
as the stoichiometric oxygen source and catalytic amounts
of a short-chain trialkylphosphine oxide ligand.
In an effort to obtain a completely homogenous mixture,
a 5–6 M solution of tert-butyl hydroperoxide (TBHP) in
decane was used as the stoichiometric oxidant (Table 4).
The Mimoun complexes change color and form uncharac-
Table 4 Catalytic Epoxidations with Crystalline MoO5·R3PO·L Complexes and t-BuOOH (5–6 M in decane) as the Stoichiometric Oxidant
(Method 3)
(5–6 M in decane), t-BuOOH (3–4.8 equiv)
alkene
epoxide
MoO5⋅R3PO⋅L (10 mol%), CHCl3
Alkene
MoO5·R3PO·L
Temp (°C)
25
Time (days)
% NMR Conversiona
cyclooctene
2
2
2
2
2
2
3
3
6
4
95
cyclododecene
trans-dec-5-ene
7-methylocta-1,6-diene
4-phenylbut-1-ene
dodec-1-ene
30–55
25
>99
7
>99
25–40
40
7
>99 other products
6
30
25
4
trace epoxide
7-methylocta-1,6-diene
cyclododecene
25
4
50 epoxide + 50 other products
>99
25
10
a Isolated yields could not reported due to presence of large amounts of decane.
Synthesis 2007, No. 1, 92–96 © Thieme Stuttgart · New York

94
C. I. Altinis Kiraz et al.
PAPER
Table 5 Catalytic Epoxidations with the MoO5·Et3PO·L Complex Formed in situ and t-BuOOH as the Stoichiometric Oxidant (Method 2)
MoO5 (5 mol%), t-BuOH (3–4 equiv)
alkene
epoxide
R3PO (10–15 mol%), CHCl3
Alkene
t-BuOOH
Temp (°C)
30
Time
5 d
Isolated yield (%)
(% NMR conversion)
oct-1-ene
dodec-1-ene
70%
(37, epoxide)
(30, other products)
70%
reflux
60
6 h
5 h
38 (75)
7-methylocta-1,6-diene
cyclododecene
cyclooctene
70%
71 (97)
70%
35–50
30–40
35
7 d
71 (>99)
70 (97)
70%
48 h
48 h
24 h
24 h
21 h
6 h
trans-dec-5-ene
allylbenzene
70%
71 (>99)
(30)
5–6 M decane
5–6 M decane
5–6 M decane
5–6 M decane
50
cyclododecene
cyclooctene
60
52 (60 epoxide,15 diol)
71 (>99)
90 (>99)
55
7-methylocta-1,6-diene
40
til consumption of alkene was observed by TLC analysis. For the
MoO5·(Ph3PO)2 (5) and MoO5·Me3PO·MeOH (1) complexes, due
to their lack of solubility in many organic solvents, the mixture was
stirred until all of the complex dissolved. Upon consumption of the
alkene, the mixture was filtered through a short plug of silica gel us-
ing CH2Cl2 as eluent. The % conversion was measured by compar-
ison of the integration values of the starting alkene to the epoxide.
Isolated yields were reported by discounting for the amount of
CH2Cl2 present after careful rotary evaporation through integration
by 1H NMR analysis according to the method reported by Jacobsen
et al.7
terized oxidation products upon heating the reaction mix-
ture above 60 °C, so most of these reactions were
conducted at room temperature with catalytic amounts of
the crystalline Mimoun complexes. While use of TBHP in
decane resulted in formation of a homogeneous solution,
isolation of relatively volatile epoxides became difficult
due to the presence of excess decane following purifica-
tion. The instability of the crystalline complexes 2/3 to
heat in the presence of peroxide and the resultant presence
of other oxidation products with some alkene substrates,
led to another catalytic protocol modeled after the H2O2
procedure by means of generating the MoO5·R3PO·L cat-
alyst in situ with the aid of a 5–6 M solution of TBHP in
decane or a 70% solution of TBHP. Results of these oxi-
dations are summarized in Table 5. As was observed with
the other epoxidation protocols, terminal alkenes react in
low to moderate yields, while di- and trisubstituted alk-
enes undergo essentially complete conversion to the ep-
oxide as monitored by NMR spectroscopy. Thus it has
been demonstrated that catalytic amounts of short-chain
trialkylphosphine oxide ligands and MoO5 can be used to
efficiently convert di- and higher substituted alkenes to
the corresponding epoxides using a biphasic system with
either 30% hydrogen peroxide or 70% TBHP acting as the
stoichiometric oxidant.
Cyclooctene Oxide (6)11
1H NMR (CDCl3): d = 1.25–1.27 (m, 2 H), 1.4–1.66 (m, 8 H), 2.11–
2.16 (m, 2 H), 2.88–2.92 (m, 2 H).
13C NMR (CDCl3): d = 25.8, 26.6, 26.9, 55.9.
MoO5 Stock Solution
A mixture of MoO3 (3.0 g, 21 mmol) was suspended in 30% H2O2
(12.0 g, 106 mmol) and the mixture was heated to 40–45 °C for 4 h.
A yellow solution was formed and the remaining trace amount of
precipitate was filtered. The filtrate was stored in the freezer for use
in catalytic oxidations of alkenes with trialkylphosphine oxide
ligands. It was necessary to vent the filtrate from time to time if used
infrequently; otherwise the stock solution can be safely stored in the
freezer. This mixture makes approximately 1.39 mmol/g of MoO5
solution.
Epoxidation of Alkenes with Hydrogen Peroxide (Method 1);
General Procedure
For epoxidation of alkenes, detailed experimental data is only pro-
vided for epoxides that were isolated. The preparation of complexes
1–5 has been previously described.6 All reactions were run two or
three times and the values reported in Tables 1– 5 are averages of
these runs.
A mixture of alkene (1 mmol), 30% H2O2 (3–4 mmol) and MoO5
stock solution (5 mol%, 0.05 mmol) was weighed into a 10 mL
round-bottomed flask. In a separate flask, 10–15 mol% (0.10–0.15
mmol) of R3PO was dissolved in CHCl3 and added to the peroxide/
alkene mixture. The biphasic mixture was stirred at 40–70 °C until
all or most of the alkene substrate was consumed. Upon cooling to
r.t., the mixture was extracted with a minimal amount of CH2Cl2
(3 ×), washed with brine (5 mL), and dried (Na2SO4). After filtra-
tion through a short plug of silica gel using as CH2Cl2 as eluent, the
mixture was concentrated under reduced pressure by rotary evapo-
Stoichiometric Epoxidation of Cyclooctene; General Procedure
A mixture of MoO5·R3PO·L 1–3 (0.19 mmol) or MoO5·(R3PO)2 4
and 5 (0.13 mmol) and cyclooctene (25 mL, 0.19 mmol) were sus-
pended in anhyd CH2Cl2 (10 mL). The mixture was stirred at r.t. un-
Synthesis 2007, No. 1, 92–96 © Thieme Stuttgart · New York

PAPER
Trialkyl(aryl)phosphine Oxide Complexes
1,2-Epoxydodecane (8)13
Method 2: A mixture of the MoO5 stock solution (36 mg, 0.05
mmol), 70% TBHP (0.75 mL, 4.35 mmol), dodec-1-ene (172 mg,
1.0 mmol), Et3PO (20 mg, 0.12 mmol) in CHCl3 (1 mL) was re-
fluxed for 6 h to furnish the epoxide in 38% isolated yield.
95
ration in a r.t. bath. Isolated yields were calculated by correcting for
1
the presence of CH2Cl2 per integration values of H NMR spectra
according to the method of Jacobsen et al.7 In certain cases, due to
large excess of solvent, despite careful rotary evaporation, loss of
product was observed.
Method 3: A mixture of MoO5·Et3PO·MeOH (2; 51 mg, 0.15
mmol), TBHP (5–6 M in decane, 0.80 mL, 4.0–4.8 mmol), dodec-
1-ene (174 mg, 1.03 mmol) in CHCl3 (1 mL) was stirred at 25 °C
over several days which only formed a trace amount of the epoxide.
1H NMR (CDCl3): d = 0.87 (t, J = 7.2 Hz, 3 H), 1.25–1.62 (m, 18
H), 2.46 (dd, J = 2.7, 4.8 Hz, 1 H), 2.74 (dd, J = 4.2, 4.8 Hz, 1 H),
2.84–2.92 (m, 1 H).
Catalytic Epoxidation of Alkenes with tert-Butyl Hydroperox-
ide (Method 2); General Procedure
A mixture of alkene (1 mmol), t-BuOOH (TBHP, 70% or 5–6 M so-
lution in decane, 4 mmol), and MoO5 stock solution (5 mol%, 0.05
mmol) was weighed into a 10 mL round-bottomed flask. In a sepa-
rate flask, 10–15 mol% (0.10–0.15 mmol) of R3PO was dissolved in
CHCl3 (1 mL) and added to the peroxide/alkene mixture. The bipha-
sic mixture was stirred at 40–70 °C until all or most of the alkene
substrate was consumed. Upon cooling to r.t., the mixture was ex-
tracted with CH2Cl2 (2 × 10 mL), washed with brine (5 mL), and
dried (Na2SO4). After filtration through a short plug of silica gel us-
ing CH2Cl2 as eluent, the mixture was concentrated under reduced
pressure by rotary evaporation with a room temperature bath. When
necessary, the epoxides were purified by flash chromatography over
a short column of silica gel using CH2Cl2 as eluent. In cases where
a 5–6 M solution of TBHP was used, products could not be isolated
due to the presence of excess decane. Isolated yields were calculat-
ed by correcting for the presence of CH2Cl2 per integration values
of the 1H NMR spectra according to the method of Jacobsen et al.7
13C NMR (CDCl3): d = 14.4, 22.9, 26.2, 29.5, 29.7, 29.78, 29.8,
32.1, 32.7, 47.4, 52.7, 58.3.
Cyclooctene Oxide (6)12
Method 1: A mixture of the MoO5 stock solution (34 mg, 0.05
mmol), 30% H2O2 (512 mg, 4.52 mmol), cyclooctene (120 mg, 1
mmol), and trialkyl or Ph3PO (29 mg, ~0.12 mmol) in CHCl3 (1 mL)
was heated to 40–55 °C for 18–24 h to furnish the epoxide in isolat-
ed yields of 81–95%.
Method 2: A mixture of the MoO5 stock solution (41 mg, 0.05
mmol), 70% TBHP (0.75 mL, 4.35 mmol), cyclooctene (123 mg,
1.12 mmol), and Et3PO (18 mg, 0.11 mmol) in CHCl3 (1 mL) was
heated to 35–50 °C over 7 d to afford the epoxide in a 70% isolated
yield.
Catalytic Epoxidation of Alkenes with tert-Butyl Hydroperox-
ide and Crystalline Mo Complexes (Method 3); General Proce-
dure
Method 3: A mixture of MoO5·Et3PO·MeOH (2; 51 mg, 0.15
mmol), TBHP (5–6 M in decane, 0.80 mL, 4–4.8 mmol), cy-
clooctene (162 mg, 1.50 mmol) in CHCl3 (1 mL) was stirred at
25 °C over several days which converted the olefin into the epoxide
in >99% as measured by 1H NMR spectrum. Attempts to isolate the
alkene through chromatography were unsuccessful due to large ex-
cess of decane.
1H NMR (CDCl3): d = 1.25–1.27 (m, 2 H), 1.4–1.66 (m, 8 H), 2.11–
2.16 (m, 2 H), 2.88–2.92 (m, 2 H).
13C NMR (CDCl3): d = 25.8, 26.6, 26.9, 55.9.
A mixture of alkene (1 mmol), TBHP (5–6 M solution in decane, 3–
4.8 mmol), and crystalline MoO5·R3PO·L (10 mol%) was weighed
into a 10 mL round-bottomed flask and CHCl3 (1 mL) was added.
The mixture was stirred at r.t. or heated to 40 °C until all or most of
the alkene substrate was consumed. The mixture was diluted with
H2O (10 mL) and extracted with CH2Cl2 (2 × 10 mL). The combine
organic layers were washed with brine (5 mL), and dried (Na2SO4).
After filtration through a short plug of silica gel using CH2Cl2 as
eluent, the mixture was concentrated under reduced pressure by
careful rotary evaporation with a room temperature bath. Due to the
presence of excess of decane and volatility of the epoxides the oxi-
dation products were difficult to isolate, only % conversions are re-
(E/Z)-Cyclododecene Oxide (9)14
1
Method 1: A mixture of the MoO5 stock solution (34 mg, 0.05
mmol), 30% H2O2 (512 mg, 4.52 mmol), cyclododecene (120 mg, 1
mmol), and trialkyl or Ph3PO (29 mg, ~0.12 mmol) in CHCl3 (1 mL)
was heated to 40–55 °C for 18–24 h to form the epoxide in an aver-
age yield of 94%.
ported as measured by integration values of the H NMR spectra
according to the method of Jacobsen et al.7
(E)-5,6-Epoxydecane (7)12
Method 1: A mixture of MoO5 stock solution (46 mg, 0.06 mmol),
30% H2O2 (495 mg, 4.35 mmol), trans-dec-5-ene (141 mg, 1.0
mmol), and Pr3PO (21 mg, 0.12 mmol) in CHCl3 (1 mL) was heated
to 40–55 °C for 12 h to afford the epoxide in 60% isolated yield.
Method 2: A mixture of the MoO5 stock solution (41 mg, 0.05
mmol), 70% TBHP (0.75 mL, 4.35 mmol), cyclododecene (123 mg,
1.12 mmol), Et3PO (18 mg, 0.11 mmol) and CHCl3 (1 mL) was
heated to 35–50 °C over 7 d which formed the epoxide in 71% yield.
Method 2: A mixture of MoO5 stock solution (80 mg, 0.11 mmol),
70% TBHP (0.55 mL, 4.0 mmol), and trans-dec-5-ene (144 mg,
1.03 mmol), and Et3PO (24 mg, 0.12 mmol) in CHCl3 (1 mL) was
heated to 35–50 °C over 7 d to give the epoxide in 71% isolated
yield.
Method 3: A mixture of MoO5·Pr3PO·H2O (3; 54 mg, 0.11 mmol),
TBHP (5–6 M in decane, 0.50 mL 2.5–3.0 mmol), cyclododecene
(162 mg, 1.00 mmol) in CHCl3 (1.4 mL) was stirred at 25 °C over
several days and when no reaction was observed, the mixture was
heated to 35–50 °C for 12 h, which showed a conversion of >99%
as measured by 1H NMR spectroscopy. This particular epoxide was
isolated by chromatography in 83% yield. The epoxide was ob-
tained as a cis and trans mixture.
Method 3: A mixture of MoO5·Et3PO·MeOH (2; 43 mg, 0.13
mmol), TBHP (5–6 M in decane, 0.80 mL, 4.0–4.80 mmol), and
trans-dec-5-ene (111 mg, 0.80 mmol) in CHCl3 (0.65 mL) was
stirred at 25 °C over several days. Conversion to the epoxide in
1
IR of the mixture (CH2Cl2): 2928, 2859, 1468 cm–1.
>99% was observed as measured by integration values in the H
NMR spectrum.
1H NMR (CDCl3): d = 0.90 (t, J = 6.9 Hz, 6 H), 1.3–1.6 (m, 12 H),
trans-1,2-Epoxycyclododecene
1H NMR (CDCl3): d = 1.34–1.59 (m, 18 H), 1.78–1.87 (m, 2 H),
2.90 (br d, J = 9.9 Hz, 2 H).
2.62–2.66 (m, 2 H).
13C NMR (CDCl3): d = 14.1, 22.7, 28.3, 32.0, 59.1.
13C NMR (CDCl3): d = 22.6, 23.6, 24.2, 25.2, 26.0, 58.2.
Synthesis 2007, No. 1, 92–96 © Thieme Stuttgart · New York

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C. I. Altinis Kiraz et al.
PAPER
cis-1,2-Epoxycyclododecene
References
1H NMR (CDCl3): d = 0.82–1.1 (m, 2 H), 1.34–1.59 (m, 16 H),
2.10–2.22 (m, 2 H), 2.73 (br d, J = 10.8 Hz, 2 H).
(1) (a) De Vos, D. E.; Sels, B. F.; Jacobs, P. A. Adv. Synth.
Catal. 2003, 345, 457. (b) Lee, N. H.; Jacobsen, E.
Tetrahedron Lett. 1991, 32, 6533. (c) Bergeault, J.-M.
Dalton Trans. 2003, 3289. (d) Jorgensen, K. A. Chem. Rev.
1989, 89, 431. (e) Dickman, M. H.; Pope, M. T. Chem. Rev.
1994, 94, 569.
(2) (a) Butler, A.; Clague, M. J.; Meister, G. Chem. Rev. 1994,
94, 625. (b) Conte, V.; Di Furia, F.; Moro, S. J. Mol. Catal.
A 1997, 120, 93.
(3) (a) Newman, R.; Cohen, M. Angew. Chem., Int. Ed. Engl.
1997, 36, 1738. (b) Boesine, M.; Noeh, A.; Loose, I.; Krebs,
B. J. Am. Chem. Soc. 1998, 120, 7252.
(4) (a) Ramao, C. C.; Kuehn, F. E.; Hermann, W. A. Chem. Rev.
1997, 97, 3197. (b) Adam, W.; Mitchell, C. M.; Saha-
Moeller, C. R. Eur. J. Org. Chem. 1999, 785.
(5) (a) Mimoun, H.; Seree de Roch, I.; Sajus, L. Bull. Soc. Chim.
Fr. 1969, 1481. (b) Mimoun, H.; Seree de Roch, I.; Sajus, L.
Tetrahedron 1970, 26, 37. (c) Mimoun, H. Angew. Chem.,
Int. Ed. Engl. 1982, 21, 734.
(6) Altinis Kiraz, C. I.; Emge, T. J.; Jimenez, L. S. J. Org. Chem.
2004, 69, 2200.
(7) White, M. C.; Doyle, A. G.; Jacobsen, E. N. J. Am. Chem.
Soc. 2001, 123, 7194.
(8) (a) Swern, D. In Organic Peroxides, Vol. 2; Swern, D., Ed.;
Wiley-Interscience: New York, 1971, 355–533. (b)Bartlett,
P. D.; Sargent, G. D. J. Am. Chem. Soc. 1965, 87, 1297.
(9) Deubel, D. V.; Sundermeyer, J.; Frenking, G. Eur. J. Inorg.
Chem. 2001, 1819.
13C NMR (CDCl3): d = 24.0, 24.1, 25.7, 26.8, 31.5, 59.9.
2,3-Epoxy-2-methyloct-7-ene (10)15
Method 1: A mixture of the MoO5 stock solution (34 mg, 0.05
mmol), 30% H2O2 (512 mg, 4.52 mmol), diene (120 mg, 1 mmol),
and trialkyl or Ph3PO (29 mg, ~0.12 mmol) in CHCl3 (1 mL) was
heated to 40–55 °C for 18–24 h forming the epoxide in yields of 70–
95%.
Method 2: A mixture of the MoO5 stock solution (62 mg, 0.09
mmol), 70% TBHP (1.00 mL, 4.35 mmol), diene (223 mg, 1.77
mmol), Et3PO (36 mg, 0.12 mmol), and CHCl3 (1 mL) was heated
to reflux for 5 h which formed the epoxide in 71% yield.
Method 3: A mixture of MoO5·Pr3PO·H2O (3; 62 mg, 0.15 mmol),
TBHP (5–6 M in decane, 0.80 mL, 4.0–4.8 mmol), diene (128 mg,
1.0 mmol) in CHCl3 (1 mL) was stirred at 25 °C over several days
until the alkene was consumed resulting in 50% conversion to the
1
epoxide as measured by H NMR spectroscopy. Other oxidation
products were not characterized.
1H NMR (CDCl3): d = 1.24 (s, 3 H), 1.28 (s, 3 H), 1.5–1.56 (m, 4
H), 2.1 (q, J = 6.9 Hz, 2 H), 2.69 (t, J = 5.9 Hz, 1 H), 4.9–5.0 (m, 2
H), 5.74–5.88 (m, 1 H).
13C NMR (CDCl3): d = 18.7, 24.8, 25.8, 28.3, 33.5, 58.2, 64.3,
114.7, 138.3.
1,2-Epoxy-4-phenylbutane (11)16
(10) (a) Schulz, M.; Teles, J. H.; Sundermeyer, J.; Wahl, G.
BASF AG, US Patent 6 054 407, 2000; Chem. Abstr. 2000,
126, 279289. (b) Wahl, G.; Kleinhenz, D.; Schorm, A.;
Sundermeyer, J.; Stowasser, R.; Rummey, C.; Bringmann,
G.; Fickert, C.; Kiefer, W. Chem. Eur. J. 1999, 5, 3237.
(11) A stock solution of MoO5 was prepared by heating MoO3 in
30% H2O2 at 40 °C for 4 h.
(12) (a) Hori, T.; Sharpless, K. B. J. Org. Chem. 1978, 43, 1689.
(b) Cope, A. C.; Fenton, S. W.; Spencer, C. F. J. Am. Chem.
Soc. 1952, 74, 5884.
Method 3: A mixture of MoO5·Et3PO·MeOH (2; 44 mg, 0.12
mmol), TBHP (5–6 M in decane, 0.60 mL, 2.5–3.0 mmol), 4-phe-
nylbut-1-ene (141 mg, 1.00 mmol) in CHCl3 (1 mL) was stirred at
40 °C over several days which formed the epoxide in a 30% conver-
sion as measured by NMR spectroscopy, along with other oxidation
products which were not characterized. Efforts to isolate the ep-
oxide failed due to the low yield and presence of an excess amount
of decane.
(13) Sato, K.; Aoki, M.; Ogawa, M.; Hashimoto, T.; Noyori, R. J.
Org. Chem. 1996, 61, 8310.
(14) (a) Neimann, K.; Neumann, R. Org. Lett. 2000, 2, 2861.
(b) Kasyan, L. I.; Steponova, N. V.; Galaeeva, M. F.;
Boldeskul, I. E.; Trachevski, V. V.; Zefirov, N. S. J. Org.
Chem. USSR (Engl. Transl.) 1987, 23, 109.
Acknowledgment
We thank the National Science Foundation (CHE-0074836) and
Schering-Plough Research Institute, Kenilworth, NJ for support of
this research.
(15) (a) Steinreiber, A.; Mayer, S. F.; Faber, K. Synthesis 2001,
2035. (b) van Vliet, M. C. A.; Arends, I. W. C. E.; Sheldon,
R. A. Synlett 2001, 248. (c) Sato, T.; Yonemochi, S.
Tetrahedron 1994, 50, 7375.
(16) Solladie, G.; Demailly, G.; Greck, C. Tetrahedron Lett.
1985, 26, 435.
Synthesis 2007, No. 1, 92–96 © Thieme Stuttgart · New York