Conversion of Cyclohexanones to Alkyl Aryl Ethers by Using a Pd/C–Ethylene System

Article abstract of DOI:10.1002/ejoc.201601362

The conversion of cyclohexanone and substituted cyclohexanones into alkyl aryl ethers by using a Pd/C–ethylene system is discussed, with ethylene functioning as a hydrogen acceptor. The ether products are easily transformed into the corresponding phenols by treatment with BBr₃. The direct conversion of cyclohexenone into phenol in the presence of a catalytic amount of Pd/C under an ethylene atmosphere is also described.

Full text of DOI:10.1002/ejoc.201601362

A Journal of
Accepted Article
Title: Conversion of Cyclohexanones to Alkyl Aryl Ethers Using a Pd/C-
Ethylene System
Authors: Masahiko Hayashi, Ibrahim El-Deeb, Miaomiao Tian, Tatsuya
Funakoshi, and Ryosuke Matsubara
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To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201601362
Link to VoR: http://dx.doi.org/10.1002/ejoc.201601362
Supported by

10.1002/ejoc.201601362
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Conversion of Cyclohexanones to Alkyl Aryl Ethers Using a
Pd/C–Ethylene System
Ibrahim Yussif El-Deeb, Miaomiao Tian, Tatsuya Funakoshi, Ryosuke Matsubara, and Masahiko
Hayashi*
Abstract: The conversion of cyclohexanone and substituted
cyclohexanones to alkyl aryl ethers using a Pd/C–ethylene system is
discussed, where ethylene functions as a hydrogen acceptor. The
obtained ethers are easily transformed into the corresponding
phenols by treatment with BBr3. Direct conversion of cyclohexenone
to phenol in the presence of a catalytic amount of Pd/C under an
ethylene atmosphere is also described.
nanoparticles functioned as a catalyst. Here, we would like to
report a Pd/C-catalyzed synthesis of alkyl aryl ethers under
ethylene atmosphere followed by ether de-alkylation, leading to
the formation of phenols (Eq. 2). The direct conversion of
cyclohexenone to phenol using a Pd/C–ethylene system is also
disclosed (Eq. 3).
Introduction
Development of phenol synthesis is one of the most important
subjects in both industrial and academic fields.[1] In 1947, E. C.
Horning and M. G. Horning reported that dehydrogenation of 3-
methyl-5-(p-methoxyphenyl)-2-cyclohexene-1-one
on
Pd/C
afforded 3-methyl-5-(p-methoxyphenyl)phenol.[2] To the best of
our knowledge, this is the first report of a palladium-catalyzed
dehydrogenation to form phenols; however, the examples shown
are limited and require high temperature (up to 252 °C). In 1963,
Kosower and Wu reported the transformation of cyclohex-2-en-
1-one (cyclohexenone) into phenol using
a stoichiometric
amount of CuCl2, LiCl, and DMF as solvent.[3] Subsequently, in
1977, Pucci and coworkers expanded the scope of substrates,
e.g., to include the A ring of steroids.[4] Concerning the catalytic
system, palladium- and other transition metal-catalyzed
reactions have been reported for both homogeneous and
heterogeneous media;[5] however, most of them lack substrate
generality or have problematic yields or reaction conditions. In
2000, we reported the transformation of cyclohex-2-en-1-ol
(cyclohexenol) or cyclohexenone using a catalytic amount of
Pd(OAc)2 under ethylene atmosphere (1 atm).[6] Ethylene
functioned as an effective hydrogen acceptor in those hydrogen
transfer reactions, and quantitative generation of ethane was
observed at the end of the reactions. Following our study, some
other reactions producing phenols via cyclohexenones were
reported, including Pd-catalyzed aerobic oxidation of
cyclohexanone. Among those, Stahl and coworkers reported
aerobic dehydrogenation of cyclohexanone to phenol catalyzed
by Pd(TFA)2/2-dimethylaminopyridine (Eq. 1).[7] On the basis of
detailed experiments, including kinetic studies, filtration tests, Hg
poisoning experiments, transmission electron microscopy, and
dynamic light scattering measurements, it was proposed that Pd
Very recently, Tokunaga and his co-workers also reported
aerobic oxidation of cyclohexanones to phenols and aryl ethers
using supported Pd catalysts.[8]
Results and Discussion
We first examined the reaction of cyclohexanone with hexanol in
the presence of a catalytic amount of Pd/C under ethylene
atmosphere under various conditions. 5% Pd/C (5 mol.%), in
xylene at 130 °C for 48 h proved to be the best choice, affording
hexyl phenyl ether in 90% yield. The results of the reaction of
substituted cyclohexanones with alcohols are summarized in
Table 1.
Table 1. Reaction of cyclohexanones with alcohols in the presence of Pd/C
under ethylene atmosphere[a]
[a]
I. Y. El-Deeb, M. Tian, T. Funakoshi, Prof. Dr. R. Matsubara, Prof.
Dr. M. Hayashi
Department of Chemistry
Graduate School of Science
Kobe University, Nada, Kobe 657-8501, Japan
E-mail: mhayashi@kobe-u.ac.jp
http://www2.kobe-u.ac.jp/~mhayashi/
Entry
Ketone
Alcohol
Ether
2a
Yield/%
90 (20)[b]
77 (20)[c]
91
1
2
3
cyclohexanone (1a)
cyclohexanone (1a)
2-methylcyclohexanone (1b)
C6H13OH
c-C6H11OH
C6H13OH
2b
Supporting information for this article is given via a link at the end of
the document.
2c
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10.1002/ejoc.201601362
European Journal of Organic Chemistry
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reactions under argon atmosphere also afforded ethers in
smaller yields (Entries 1 and 2 in Table 2).
2d
2e
2f
78
85
61
4
5
6
2-methylcyclohexanone (1b)
3-methylcyclohexanone (1c)
3-methylcyclohexanone (1c)
c-C6H11OH
C6H13OH
c-C6H11OH
Table 2. Reaction of cyclohexenones with alcohols in the presence of Pd/C
under ethylene atmosphere[a],[b]
3,5-dimethylcyclohexanone
(1d)
2g
2h
82
7
8
C6H13OH
3,5-dimethylcyclohexanone
(1d)
17 (56)[d]
c-C6H11OH
[a] The reactions were carried out at 130 °C for 48 h using ketone (3 mmol)
and alcohol (15 mmol) in the presence of 5% Pd/C (Strem Chemicals
Escat 1431, 5 mol.%) under ethylene atmosphere (1 atm). The reported
value refers to the yield of product isolated after silica gel column
chromatography.
[b] Phenol was obtained in 5% yield. The number in parentheses indicates
the yield obtained when argon was used instead of ethylene. [c] The
number in parentheses indicates the yield obtained when argon was used
instead of ethylene. [d] The value in the parentheses indicates the recovery
of 3,5-dimethylcyclohexanone.
Entry
Enone
Alcohol
Ether
Yield [%]
Phenol
Yield [%]
1
2
3
4
5
6
3a
3a
3b
3b
3c
3c
C6H13OH
c-C6H11OH
C6H13OH
c-C6H11OH
C6H13OH
c-C6H11OH
2a
2b
2e
2f
45 (11) [c]
28 (13) [c]
4a
4a
4b
4b
4c
4c
40 (45) [c]
69 (36) [c]
The reaction of cyclohexanone (1a) and substituted
cyclohexanones (1b–1d) with alcohols proceeded smoothly,
affording the corresponding aryl hexyl ethers in good to high
yields (61–90%), with the exception of entry 8. From the
viewpoint of alkyl aryl ether preparation, this method is
comparable to palladium-catalyzed C–O bond formation
(Buchwald-Hartwig coupling), although the concept and
mechanism are completely diffferent.[9] It should be noted that
when the reaction was carried out under argon atmosphere, the
product was obtained in low yields (20–22%, Entries 1 and 2 in
Table 1, see also Table S1 in Supporting Information). We used
Pd/C sourced from Strem Chemicals (Escat 1431) in these
reactions; however, we could not observe any meaningful
difference of catalytic activity compared to the Pd/C sold by
Sigma-Aldrich, Wako Pure Chemical Industries, Ltd., and Tokyo
Chemical Industry Co., Ltd.
45
30
51
30
49
65
44
63
2g
2h
[a] All reactions were carried out at 130 °C for 48 h using enone (3 mmol)
and alcohol (15 mmol) in the presence of 5% Pd/C (Strem Chemicals
1431, 5 mol.%) under ethylene atmosphere (1 atm). [b] Yilelds were
isolated yield after silica gel column chromatography. [c] The values in
parentheses indicate the yield when argon was used instead of ethylene.
To clarify the mechanism of cyclohexanone transformation into
hexyl phenyl ether, we prepared cyclohexanone dihexylacetal
and hexyl cyclohexenyl ether to be used as substrates. As
shown in Eqs. 5, 6 and 7, treatment of cyclohexanone
dihexylacetal and cyclohexenyl hexyl ether with 5% Pd/C (5
mol.%) under ethylene atmosphere afforded hexyl phenyl ether
in 92%, 60% (in xylene), and 84% yield, respectively. Thus, it
would be reasonable to think that the reaction proceeds via one
or both of these intermediates.
The reactions of (1a), (1b), and (1c) with other alcohols also
proceeded smoothly to afford the corresponding alkyl phenyl
ethers. Some of the results are shown below.
Lemaire and coworkers reported
a
similar type of
dehydrogenation under aerobic and non-aerobic conditions.[10],
The obtained ethers were quantitatively converted to phenol by
treatment with BBr3 (Eq.4). Therefore, the present two-step
system, converting cyclohexanone to alkyl phenyl ethers that are
dealkylated to produce phenols, provides an efficient method for
phenol synthesis.
GC mass spectra of a mixture of cyclohexanone, hexanol, and
5% Pd/C (5 mol.%) reacted under ethylene atmosphere for 30
min showed the presence of cyclohexenyl hexyl ether, hexyl
phenyl ether, and cyclohexanone dihexylacetal in addition to
starting materials (see Supporting Information). When a mixture
of cyclohexenyl hexyl ether, hexanol, and 5% Pd/C (5 mol.%)
was reacted under ethylene atmosphere for 15 min, hexyl
phenyl ether, cyclohexanone dihexylacetal, and cyclohexyl hexyl
ether were observed in addition to starting materials (See
Next, cyclohexenones were reacted with alcohols in the
presence of 5% Pd/C (5 mol.%) under ethylene atmosphere
(Table 2). In this case, direct conversion of 2-cyclohexenone to
phenols occurred, as is discussed later, leading to the formation
of mixtures of alkyl aryl ethers and phenols. In this case, the
Supporting Information).
These results indicate that
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10.1002/ejoc.201601362
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cyclohexanone dihexylacetal and cyclohexenyl hexyl ether exist
in equilibrium, and the reaction proceeds via one and/or the
other intermediate.
In conclusions, conversion of cyclohexanone and substituted
cyclohexanones to alkyl aryl ethers using a Pd/C–ethylene
system was developed. In these reactions, ethylene functions as
a
hydrogen acceptor. The obtained ethers are easily
transformed into the corresponding phenols by treatment with
BBr3. Direct conversion of cyclohexenone to phenol in the
presence of
a catalytic amount of Pd/C under ethylene
atmosphere (3 atm) was also performed. The present method
has advantages over the previous methods from the points that
1) Use of cheap and industrial ethylene as a hydrogen acceptor;
2) The co-product is only gaseous ethane; 3) operational
simplicity, and so on. Further investigations towards other
coupling reactions using our catalytic system are currently in
progress.
Experimental Section
Scheme 1. Possible reaction mechanism for forming alkyl aryl ethers from
cyclohexanone.
General
All reactions were carried out in well-cleaned and oven-dried glassware
under magnetic stirring. All starting materials were obtained from
commercial sources or were synthesized using standard procedures.
Melting points were measured on a Yanaco MP-500D instrument and
were not corrected. 1H and 13C NMR spectra (400 and 100 MHz,
Finally, direct conversion of cyclohexenone to phenol was
examined. As shown in eq. 8, both of phenol and cyclohexanone
were formed in approximately the same amounts in absence of
ethylene. Cyclohexanone was formed by hydrogenation of
cyclohexenone. On the other hand, the reaction under ethylene
atmosphere (1 atm) favored phenol (64%) over cyclohexanone
(32%), indicating that ethylene functioned as a hydrogen
acceptor. Furthermore, at an ethylene pressure of 3 atm (using
an autoclave), phenols were exclusively obtained (eqs. 10__12).
respectively) were recorded on
a Bruker Avance III HD 400
spectrometer; TMS (0 ppm) and CDCl3 (77.0 ppm) were used as internal
standards, respectively. The following abbreviations are used to describe
NMR peak multiplicity: s = singlet, d = doublet, t = triplet, q = quartet, and
m = multiplet. GC mass spectra were measured on a Thermo Auest LCQ
DECA Plus instrument with GL Sciences Inc. Inert Cap5 as a column
(70–310 °C). GC analyses were performed using a Shimadzu GC-2025
gas chromatograph equipped with GL Science Inert Cap5 (70–310 °C).
Preparative column chromatography was performed with Fuji Silysia BW-
4:10MH silica gel or YMC_GEL Silica (6 nm I-40-63 m). Thin layer
chromatography (TLC) was carried out on Merck 25 TLC silica gel 60
F254 aluminum sheets.
Typical procedure for the reaction of cyclohexanone with hexanol
(using a two-necked flask connected with a reflux condenser and a
balloon).
A portion of 5% Pd/C (Strem Chemicals Escat 1431, 5 mol % with
respect to cyclohexanone) was placed in a two-necked flask connected
with a reflux condenser and a balloon. Hexanol (1.9 mL, 15 mmol) and
cyclohexanone (310 L, 3 mmol) were added under ethylene atmosphere.
After stirring at 130 °C for 48 h, the mixture was filtered through Celite
and the filtrate was condensed.
The residue was column
chromatographed on silica gel to afford hexyl phenyl ether (480 mg,
90%) as a colorless liquid.
Typical procedure for the conversion from cyclohex-2-en-1-one to
phenol. (using autoclave).
To a mixture of 5% Pd/C (Strem Chemicals Escat 1431, 5 mol.% with
respect to cyclohexenones) and cyclohex-2-en-1-one (1.1 mL, 10.4
mmol) in acetonitrile (10 mL) were capped in autoclave under ethylene
atmosphere (3 atm) at 80 °C for 24 h, the mixture was filtered through
Celite and the filtrate was condensed. The residue was column
chromatographed on silica gel to afford phenol (880 mg, 90%) as a
colorless liquid.
Hexyl phenyl ether (2a). 1H NMR (400 MHz, CDCl3):  = 0.92 (t, J = 7 Hz,
3H), 1.31__1.38 (m, 4H), 1.43__1.50 (m, 2H), 1.74__1.82 (m, 2H), 3.95 (t, J
= 6.6 Hz, 2H), 6.88__6.96 (m, 3H), 7.26__7.30 (m, 2H); 13C NMR (100
MHz, CDCl3):  = 12.9, 21.6, 24.7, 28.2, 30.6, 66.7, 113.4, 119.3, 128.3,
158.1; MS m/z:178.2 (6.0), 94.0 (100), 77.0 (9.6). tR = 9.9 min.
Conclusions
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10.1002/ejoc.201601362
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Cyclohexyl phenyl ether (2b). 1H NMR (400 MHz, CDCl3):  = 1.18__1.33
(m, 3H), 1.38__1.52 (m, 3H), 1.68__1.76 (m, 2H), 1.87__1.95 (m, 2H),
4.11__4.19 (m, 1H), 6.80__6.85 (m, 3H), 7.14__7.20 (m, 2H); 13C NMR
(100 MHz, CDCl3):  = 22.7, 24.6, 30.8, 74.2, 115, 119.4, 128.3, 156.7;
MS m/z:176.3 (5.0), 94.1 (100), 77.1 (9.6). tR = 10.3 min.
Hz, 1H); 13C NMR (100 MHz, CDCl3):  = 12.9, 21.6, 24.7, 28.2, 30.6,
66.7, 113.4, 119.3, 128.3, 158.1.
Methyl 3,5-dimethylphenyl ether (2l). Colorless liquid; 1H NMR (400 MHz,
CDCl3):  = 2.28 (s, 6H), 3.75 (s, 3H), 6.52 (s, 2H), 6.59 (s, 1H); 13C NMR
(100 MHz, CDCl3):  = 21.4, 55.1, 111.7, 122.4, 139.2, 159.6.
Phenol (4a). 1H NMR (400 MHz, CDCl3):  = 6.04 (s, 1H), 6.82 (d, J = 7.6
Hz, 2H), 6.90 (t, J = 7.5 Hz, 1H), 7.17__7.23 (m, 2H); 13C NMR (100 MHz,
CDCl3):  = 115.5, 121.1, 129.8, 155.2; tR = 5.5 min.
Butyl phenyl ether (2m). Colorless oil; 1H NMR (400 MHz, CDCl3):  =
0.97 (t, J = 7.4 Hz, 3H), 1.42__1.54 (m, 2H), 1.72__1.79 (m, 2H), 3.94 (t, J
= 6.8 Hz, 2H), 6.87__6.93 (m, 3H), 7.23__7.29 (m, 2H); 13C NMR (100
MHz, CDCl3):  = 13.9, 19.3, 31.4, 67.8, 114.5, 120.4, 129.4, 159.2.
Hexyl 2-methylphenyl ether (2c). 1H NMR (400 MHz, CDCl3):  = 0.90 (t,
J = 6.2 Hz, 3H), 1.25__1.35 (m, 4H), 1.41__1.51 (m, 2H), 1.73__1.80 (m,
2H), 2.21 (s, 3H), 3.91 (t, J = 6.6 Hz, 2H), 6.75__6.83 (m, 2H), 7.08__7.13
(m, 2H); 13C NMR (100 MHz, CDCl3):  = 12.9, 15.2, 21.6, 24.8, 28.4,
30.6, 66.7, 109.8, 118.9, 125.6, 129.5, 156.2; MS m/z:192.3 (7.0), 108.1
(100). tR = 10.6 min.
Isopropyl phenyl ether (2n). Colourless liquid; 1H NMR (400 MHz,
CDCl3):  = 1.32 (d, J = 6 Hz, 6H), 4.49__4.57 (m, 1H), 6.86__6.92 (m, 3H),
7.22__7.28 (m, 2H); 13C NMR (100 MHz, CDCl3):  = 22.1, 69.7, 115.9,
120.5, 129.4, 157.9.
Cyclohexyl 2-methylphenyl ether (2d). 1H NMR (400 MHz, CDCl3):  =
1.25__1.34 (m, 3H), 1.45__1.55 (m, 3H), 1.67__1.75 (m, 2H), 1.83__1.91 (m,
2H), 2.15 (s, 3H), 4.13__4.20 (m, 1H), 6.72__6.85 (m, 2H), 7.02__7.19 (m,
2H); 13C NMR (100 MHz, CDCl3):  = 15.3, 22.5, 24.7, 30.8, 74.2, 112.1,
3,5-Dimethylphenol (4c). 1H NMR (400 MHz, CDCl3):  = 2.23 (s, 6H),
5.29 (s, 1H), 6.46 (s, 2H), 6.58 (s, 1H); 13C NMR (100 MHz, CDCl3):  =
21.3, 113.2, 122.6, 139.6, 155.3.
119.1, 125.5, 127.9, 129.7, 154.9; MS m/z:190.3 (5.0), 108.2 (100). tR
=
Cyclohexanone 1,1-dihexyl acetal. 1H NMR (400 MHz, CDCl3):  = 0.89 (t,
J = 7 Hz, 6H), 1.24__1.65 (m, 16H), 3.36 (t, J = 6.8 Hz, 4H); 13C NMR
(100 MHz, CDCl3):  = 14.1, 22.7, 23.1, 25.8, 26.2, 30.2, 31.8, 33.8, 59.4,
99.8; MS m/z: 284.4 (0.5), 183.3 (34), 99.2 (100). tR = 13.4 min.
11.0 min.
2-Methylphenol. 1H NMR (400 MHz, CDCl3):  = 2.26 (s, 3H), 4.64 (s, 1H),
6.76__6.88 (d, 2H), 7.07__7.13 (m, 1H).
Cyclohexyl hexyl ether. 1H NMR (400 MHz, CDCl3):  = 0.87__0.93 (m,
3H), 1.20__1.37 (m, 10H), 1.51__1.61 (m, 4H), 1.72__1.73 (m, 2H),
1.90__1.94 (m, 2H), 3.17__3.22 (m, 1H), 3.41__3.43 (m, 2H); 13C NMR
(100 MHz, CDCl3):  = 13.1, 21.6, 23.6, 24.8, 29.2, 30.7, 31.4, 66.9, 69.9;
MS m/z: 184.4 (5.0), 141.1 (16), 83.2 (100). tR = 9.2 min
Hexyl 3-methylphenyl ether (2e). 1H NMR (400 MHz, CDCl3):  = 0.81 (t,
J = 7.2 Hz, 3H), 1.20__1.26 (m, 4H), 1.23__1.40 (m, 2H), 1.62__1.70 (m,
2H), 2.21 (s, 3H), 3.81 (t, J = 6.8 Hz, 2H), 6.56__6.65 (m, 3H), 7.01__7.06
(m, 1H); 13C NMR (100 MHz, CDCl3):  = 13, 20.4, 21.6, 24.7, 28.3, 30.6,
66.7, 110.2, 114.3, 120.2, 128.1, 138.2, 158.1; MS m/z:192.3 (7.0), 108.1
(100). tR = 10.8 min.
1-Cyclohexenyl hexyl ether. 1H NMR (400 MHz, CDCl3):  = 0.87__0.91
(m, 3H), 1.28__2.07 (m, 16H), 3.59__3.65 (m, 2H), 4.58__4.60 (m, 1H); MS
m/z: 182.2 (5.0), 141.1 (17), 98.1 (100). tR = 9.8 min.
1
Cyclohexyl 3-methylphenyl ether (2f). H NMR (400 MHz, CDCl3):  =
1.20__1.33 (m, 3H), 1.38__1.52 (m, 3H), 1.67__1.76 (m, 2H), 1.86__1.95 (m,
2H), 2.23 (s, 3H), 4.10__4.18 (m, 1H), 6.60__6.74 (m, 3H), 7.03__7.08 (m,
1H); 13C NMR (100 MHz, CDCl3):  = 20.4, 22.7, 24.6, 30.8, 74.1, 111.7,
116.9, 120.2, 128.1, 138.3, 156.7; MS m/z:190.2 (5.0), 108.1 (100). tR
=
11.2 min.
Acknowledgements
3-Methylphenol (4b). 1H NMR (400 MHz, CDCl3):  = 2.26 (s, 3H), 5.43 (s,
1H), 6.61__6.65 (m, 2H), 6.74 (d, J = 7.2 Hz, 1H), 7.10(t, J = 7.8 Hz, 1H);
13C NMR (100 MHz, CDCl3):  = 21.3, 112.3, 116.1, 121.7, 129.8, 139.9,
155.3.
The work was supported by the Ministry of Education, Culture,
Sports, Science and Technology (MEXT), Japan, and by Special
Coordination Funds for Promoting Science and Technology,
Creation of Innovation Centers for Advanced Interdisciplinary
Research Areas (Innovative Bioproduction Kobe), MEXT, Japan.
3,5-Dimethylphenyl hexyl ether (2g). 1H NMR (400 MHz, CDCl3):  = 0.89
(t, J = 7 Hz, 3H), 1.28__1.36 (m, 4H), 1.39__1.47 (m, 2H), 1.68__1.76 (m,
2H), 2.25 (s, 6H), 3.86 (t, J = 6.6 Hz, 2H), 6.53 (s, 2H), 6.58 (s, 1H); 13
C
Keywords: phenol • Pd/C • dehydrogenation • hydrogen transfer
• hydrogen accepter
NMR (100 MHz, CDCl3):  = 13, 20.3, 21.6, 24.7, 28.4, 30.6, 66.6, 111.2,
121.1, 137.9, 158.2; MS m/z:206.1 (59), 122 (100).
Cyclohexyl 3,5-dimethylphenyl ether (2h). 1H NMR (400 MHz, CDCl3): 
= 1.33__1.41 (m, 3H), 1.45__1.60 (m, 3H), 1.77__1.83 (m, 2H), 1.94__2.01
(m, 2H), 2.27 (s, 6H), 4.17__4.25 (m, 1H), 6.50 (s, 2H), 6.54 (s, 1H); 13C
NMR (100 MHz, CDCl3):  = 20.4, 22.8, 24.6, 30.9, 74.1, 112.7, 121.2,
138.1, 156.7; MS m/z :204.2 (50), 122 (100).
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Methyl phenyl ether (2i). Yellow liquid; 1H NMR (400 MHz, CDCl3):  =
3.75 (s, 3H), 6.85__6.94 (m, 3H), 7.23__7.28 (m, 2H); 13C NMR (100 MHz,
CDCl3):  = 55.4, 113.9, 120.7, 129.5, 159.6.
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10.1002/ejoc.201601362
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Entry for the Table of Contents
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Key Topic* Pd/C–ethylene system; non
aerobic oxidation
Ibrahim Yussif El-Deeb, Miaomiao Tian,
Tatsuya Funakoshi, Ryosuke
Matsubara, and Masahiko Hayashi**
Page No. – Page No.
The conversion of cyclohexanone and substituted cyclohexanones to alkyl aryl
ethers using a Pd/C–ethylene system is disclosed. The obtained ethers are easily
transformed into corresponding phenols by treatment with BBr3. Direct conversion
of cyclohexenone to phenol is also described.
Title
Conversion of Cyclohexanones to Alkyl
Aryl Ethers Using a Pd/C–Ethylene
System
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