Alcohol oxidation with H2O2 catalyzed by a cheap and promptly available imine based iron complex

Article abstract of DOI:10.1039/c6ob01984f

We previously reported that the iminopyridine iron(II) complex 1, easily and quantitatively obtainable in situ, can activate H₂O₂ to form a powerful oxidant, capable of aliphatic C-H bond hydroxylation. In the present study we expand the application of this catalyst to the oxidation of a series of alcohols to the corresponding carbonyl compounds. The oxidation of aliphatic alcohols proceeds smoothly, while that of benzylic alcohols is shown to be challenging. Some collected pieces of evidence suggest a preference of the oxidizing species for the aromatic ring instead for the alcoholic moiety. The decrease of the electron density in the aromatic ring shifts the oxidation from the aromatic towards the alcoholic moiety. Quite surprisingly, preferential oxidation of cyclohexanol versus benzylic alcohol was achieved, showing unprecedented selectivity.

Full text of DOI:10.1039/c6ob01984f

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DOI: 10.1039/C6OB01984F
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Alcohol Oxidation with H2O2 Catalyzed by a Cheap and Promptly
Available Imine Based Iron Complex.
Giorgio Olivo,a,b Simone Giosia,a Alessia Barbieri,a Osvaldo Lanzalungaa and Stefano Di Stefano*a
Received 00th January 20xx,
Accepted 00th January 20xx
We previously reported that the iminopyridine iron (II) complex 1, easily and quantitatively obtainable in situ, can activate
H2O2 to form a powerful oxidant, capable of aliphatic C-H bond hydroxylation. In the present study we expand the
application of this catalyst to the oxidation of a series of alcohols to the corresponding carbonyl compounds. The oxidation
of aliphatic alcohols proceedes smoothly, while that of benzylic alcohols is shown to be challenging. Some collected pieces
of evidence suggest a preferency of the oxidizing species for the aromatic ring instead for the alcoholic moiety. The
decrease of the electron density in the aromatic ring shifts the oxidation from the aromatic towards the alcoholic moiety.
Quite surprisingly, preferential oxidation of cyclohexanol versus benzylic alcohol was achieved, showing an unprecedented
selectivity.
DOI: 10.1039/x0xx00000x
www.rsc.org/
oxidation reactions, mimicking natural nonheme iron
oxygenases.7–14 Iron-catalyzed alcohol oxidation with H2O2 has
been first explored by Beller and coworkers,15–18 and in the last
Introduction
Alcohol oxidation is a fundamental reaction in organic
synthesis, since it converts readily available alcohols into
decade several iron complexes have been reported to mediate
19–25
alcohol oxidation with H2O2
or t-BuOOH.26 Also
valuable
carbonyl
compounds,
prone
to
further
manganese-based catalysts in combination with H2O2 provided
promising results in alcohol oxidation.27–30
In this scenario, we exploited the imine chemistry31–34 to
simplify the catalyst structure and to prepare the simple
functionalization. Accordingly, several methodologies have
been developed over the years to perform such reaction.
However, most of them rely on toxic and/or polluting reagents,
such as CrO3 or hypervalent iodine.1,2 The rising environmental
concerns in our society call for greener methodologies that
require more efficient and sustainable processes. In this context,
the use of a non-polluting catalyst in combination with a readily
available and waste-free terminal oxidant (such as H2O2 or O2)
is an optimal choice. Great advances have been achieved in the
last decades by replacing toxic and/or rare transition metals
with cheaper and more environmentally friendly ones. For
instance, the Cu/air/TEMPO catalytic systems pioneered by
Stahl3,4 or the tungsten oxide/phase transfer catalysts developed
by Noyori5 gave brilliant results. Catalytic systems based on
iron complexes and hydrogen peroxide are highly attractive in
this regard, due to the large availability and low environmental
impact of the iron coupled with the high atom-economy of
H2O2.6 Indeed, aminopyridine iron complexes have been
recently demonstrated to promote effective and highly selective
iminopyridine iron complex
1 that was found to be an effective
catalyst for aliphatic C-H oxidation with H2O2.35 Very
gratifyingly we obtained results comparable to the ones
reported for far more sophisticated catalysts.34,36–38
Conveniently, complex
prepared in situ by the self-assembly of cheap and
commercially available 2-picolylaldehyde , 2-picolylamine
and Fe(CF3SO3)2 added in acetonitrile solution in a 2:2:1 ratio
(see Scheme 1).¶ Most interestingly, we found that catalyst
1 can be easily and quantitatively
2
3
1
operates through a mechanism fully devoid of free diffusing
radical intermediates, and hence is able of stereoretentive
oxidations.39 The oxidation is metal-based, and the H2O2
activation mechanism follows a path different from that
generally observed for iron nonheme based imine catalysts.34,40
a. Dipartimento di Chimica, Università degli Studi di Roma “La Sapienza” and Istituto
CNR di Metodologie Chimiche (IMC-CNR), Sezione Meccanismi di Reazione, c/o
Dipartimento di Chimica, Università degli Studi di Roma “La Sapienza”, P.le A.
Moro 5, I-00185 Rome, Italy.
b. Current address: Institut de Química Computacional i Catàlisi (IQCC) and
Departament de Química, Universitat de Girona, Campus de Montilivi, 17071
Girona, Spain.
Scheme 1: In situ formation of complex
Fe(CF3SO3)2.
1 by self-assembly of 2, 3 and
*E-mail: stefano.distefano@uniroma1.it;
Electronic Supplementary Information (ESI) available: Instrument and general
methods, materials, experimental procedures, selected chromatograms. See
DOI: 10.1039/x0xx00000x
The good results obtained in hydrocarbon oxidation under mild
reaction conditions prompted us to extend our study to the
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Table 1. Oxidation of cyclohexanol to cyclohexanone catalyzed by complex 1.a
oxidation of the alcoholic function, and the data collected in
such investigations are reported in the present paper.
View Article Online
DOI: 10.1039/C6OB01984F
cat load
(mol %)
H2O2
(eq.)
temp
(°C)
co-solv
(20%)
conv
(%)b
yield
(%)b,c
entry
Results and discussion
With our imine-based iron complex
1 in hand, we initially
1
2
0.5
1
1.5
“
25
“
-
51
86
86
92
42
88
39
93
92
100
70
84
57
70
30
70
45
67
74
76
41
67
29
74
57
70
58
59
47
58
12
51
carried out a set of cyclohexanol to cyclohexanone oxidation by
H2O2 exploring different reaction conditions (Scheme 2 and
Table 1). The reaction is clean, with cyclohexanone as the only
product (see GC chromatograms in the ESI). At first, the effect
of catalyst loading was investigated. A marked enhancement of
catalytic activity is evident on the increase of catalyst loading
from 0.5 to 1 mol%, while further increase to 3 mol% and even
to 5 mol% has a moderate impact (the yield increases from 67
to 74 % and from 74 to 76%, respectively, entries 1-4 of Table
1), suggesting a saturation behaviour for the catalytic activity
versus catalyst loading. As reported also for other nonheme iron
complexes,7 slow addition of the oxidant is crucial (compare
entries 2 and 5) in order to avoid high H2O2 concentration,
-
3
3
“
“
-
4
5
“
“
-
5
1d
1 e
1 f
1
“
“
-
6
“
“
-
7
“
“
-
8
2.5
3.5
2.5
1.5
1.5
1.5
“
“
-
9
“
“
-
10
11
12
13
14
15
16
3
“
-
-
1
0
40
25
“
which
leads
to
unproductive
consumption
by
“
-
disproportionation. Further increase of the addition time does
not have any significant impact (entry 6).
Acetic acid does not exert any beneficial effect (see entry 7), in
line with what observed in aliphatic C-H oxidation mediated by
1 39
. Increase of the oxidant amount leads to higher yields, up to
1
CH2Cl2
AcOEt
acetone
TFE
“
“
“
“
“
“
“
74% with 2.5 equivalents (entry 8), but the same effect is not
observed with an additional increase of the oxidant to 3.5
equivalents (entry 9). The combination of a higher catalyst
loading (3 mol%) with 2.5 equivalents of the oxidant led to a
decrease in efficiency, probably due to cyclohexanone
overoxidation (entry 10). Any change of the reaction
temperature from 25°C has a negative impact on the outcomes
(compare entry 2 with entries 11 and 12, respectively). Catalyst
t-amyl
alcohol
17
“
“
“
59
42
aAll the reagents were added at time t = 0 apart from the oxidant (H2O2) which is
added during the first 30 min from start by a syringe pump, in CH3CN. The
reactions were quenched at 90 min from start. bGC conversions and yields
defined as (mol unrecovered substrate/mol substrate)×100 and (mol
product/mol substrate) respectively; average of three determinations (error
±2%). when % mol catalyst is 1 numeric values of yield and TON coincide. dH2O2
c
e
f
1
performances are negatively affected when a co-solvent is
added in one aliquot from start. H2O2 added during 60 min from start. Reaction
carried out in the presence of 50% AcOH.
added to acetonitrile, even though a residual and sometimes
satisfactory efficiency is retained with oxidatively robust ethyl
acetate or trifluoroethanol (TFE).
From the above screening, the conditions described in entry 8
(slow addition of 2.5 molar equivalents of H2O2, 1 mol %
As for the substitution impact, an increase of the steric
hindrance around the hydroxyl function leads to a definite
reduction of the catalytic activity, which decreases in the series
cyclohexanol (entry 8, Table 1), 2-methylcyclohexanol and 2,6-
dimethylcyclohexanol (Table 2). Competitive oxidations
carried out on 1:1 cyclohexanol/2-methylcyclohexanol and
cyclohexanol/2,6-dimethylcyclohexanol mixtures led to the
catalyst 1, 25 °C, CH3CN) were selected and adopted in the
oxidation of a series of alcohol substrates.
consistent
methylcyclohexanone
molar
ratios
(1.36)
of
and
cyclohexanone/2-
cyclohexanone/2,6-
dimethylcyclohexanone (1.68), clearly supporting the steric
origin of the selectivity.
Varying results have been obtained when the reaction was
carried out on the linear alcohol. Oxidation of 3-pentanol to 3-
pentanone proceeds smoothly (Table 2) as well as the oxidation
of cyclohexanol to cyclohexanone (Table 1, entry 8). However,
the presence of a methyl group in the β position leads to a
marked decrease in efficiency (4-methyl-2-butanol, Table 2).
2-Decanol was found to be scarcely soluble in CH3CN and 20%
CH2Cl2 was required to carried out the reaction in
homogeneous conditions. The presence of the co-solvent leads
Scheme 2
At first, the effect of the alcohol ring size was evaluated in
cyclopentanol and cycloheptanol oxidation, while 2-
methylcyclohexanol and 2,6-dimethylcyclohexanol enabled to
assess the impact of substrate steric hindrance on the catalytic
efficiency (Table 2). Both cyclopentanol and cycloheptanol are
oxidized slightly less efficiently than cyclohexanol.
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to significant yield decrease, as already found for hydrogen atom transfer (HAT) process from theView-ACrt-icHle(OOnlHine)
a
cyclohexanol (see entry 13 in Table 1).
bond to the metal-based oxidant (a mechDaOnI:is10m.10s3i9m/Cil6aOrBt0o19t8h4aFt
proposed for the oxidation of benzylic alcohols promoted by
the active species of cytochrome P45041) is facilitated by the
low BDE of the benzylic -C-H(OH) bond.42 In addition, HAT
from benzyl alcohols is also favored by the stabilization of the
partial positive charge developing on the benzylic carbon in the
TS due to polar effects.43,44 Surprisingly, disappointing results
have been obtained in the oxidation of these substrates with
Table 2. Oxidation of aliphatic alcohols to the corresponding ketones with H2O2
catalyzed by complex 1 in CH3CN at 25 °C.a
Substrate
conv (%)
77
product
yield (%)
54
catalyst
1
.
Primary benzyl alcohol and secondary
1-phenylethanol are sluggishly oxidized into the corresponding
carbonyl compounds, with poor mass balances (see entry 1 and
2 of Table 3, respectively). We speculated that the highly
67
73
51
56
54
38
electrophilic oxidizing species39 formed by reaction of
1 with
H2O2 would preferentially hydroxylate the aromatic ring,
forming a phenol which would strongly coordinate to the iron
center leading to catalyst deactivation. Such a process has been
already described with other nonheme iron oxidation catalysts,
for which
a
metal-based oxidation has been firmly
established.45–48 In support of this hypothesis, in the GC-MS
chromatograms we observed peaks assigned to aromatic
oxidation byproducts in comparable amounts to the one of the
desired ketones. Moreover, when cyclohexanol oxidation was
carried out in the presence of equimolar amounts of toluene or
benzene, catalytic activity dramatically dropped down (10%
and 11% cyclohexanone yield, respectively), reinforcing the
idea of competitive aromatic ring oxidation with subsequent
catalyst deactivation.‡ In order to investigate further this effect
we performed the oxidation of a series of 4-substituted-
1-phenylethanols, regularly varying the electron density of the
aromatic ring. The results are reported in the entries 3-7 of
Table 3. The yield of the ketone product steadily increases on
increasing the electron withdrawing power of the substituent.
Such trend is at odds with the ease of alcohol oxidation, since
the most electron rich substrate is usually the most prone to
oxidation.29 However, it can be rationalized in terms of the
ease of competitive aromatic oxidation. The more electron
donating is the substituent, the more prone to oxidation is the
aromatic ring, with respect to the alcoholic moiety. Indeed, the
same trend can be observed for the mass balance of the
reaction, indicating that the withdrawal of electron density from
the aromatic ring tends to switch the preferential oxidation site
from the arene to the benzylic position. A similar behavior has
been observed in the oxidation of alkylaromatic substrates.49
On the other hand, the presence of an electron withdrawing
group on the aromatic moiety could weaken the binding
between the phenol function derived from aromatic oxidation
with the active form of the iron complex, resulting in a less
efficient deactivation of the catalyst.
80
57
76
50c
62
61
34c
20c,d
aReaction condition as in entry 8 of Table 1. GC conversions and yields defined as
(mol unrecovered substrate/mol substrate)×100 and (mol product/mol substrate)
respectively, average of three determinations (error ±2%). Numeric values of
yield and TON coincide. breaction carried out in CH3CN/CH2Cl2 80:20. cKetone
product is accompanied by lower amounts of C-H oxidation products. dCarboxylic
acid is also detected
Primary alcohols are less prone to oxidation, and this is
reflected in the low yield obtained in 1-decanol oxidation.
Eventually, oxidation of cyclohexanol to cyclohexanone and
cycloheptanol to cycloheptanone were carried out in
preparative scale (500 mg of substrate) under the optimized
conditions. The reaction proceeds smoothly at this scale with no
losses in efficiency, yielding 67% and 50% of ketone products,
respectively (see ESI for procedures). Conveniently, the ketone
could be easily obtained pure after a quick filtration on a one
inch SiO2 layer with dichloromethane,§ demonstrating the good
potential of such catalyst for synthetic purpose.
Eventually we investigated the plausibility of an electron
transfer (ET) oxidation mechanism, akin to the one recently
reported for sulfoxidation50 and N-demethylation of N,N-
dimethylanilines processes51,52 catalyzed by nonheme iron(IV)-
oxo complexes. In the case of 1-phenyl-2,2-dimethylpropanol
oxidation, an ET mechanism would form a radical cation which
undergoes rapid fragmentation to yield benzaldehyde, in
competition with proton transfer and ketone formation (Scheme
At this point we turned our attention to benzylic alcohol
substrates. Oxidation of benzyl alcohols to carbonyl compounds
is usually more facile than oxidation of aliphatic ones since the
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3).53 When oxidation of such a substrate was carried out in the
Journal Name
Table 3. Oxidation of benzylic alcohols to the corresponding aldehydes or ketones with
View Article Online
H2O2 catalyzed by complex 1.a
DOI: 10.1039/C6OB01984F
presence of catalyst , no trace of benzaldehyde was detected.
1
Even when the more reducing 1-(3’,4’-dimethoxy)phenyl-2,2-
dimethylpropanol was used as a substrate, no trace of the
corresponding aldehyde was found in the product mixture.
Therefore, an ET oxidation mechanism can be reasonably ruled
out.
conv
(%)
yield
(%)
Entry
1b
substrate
product
51
21
In contrast with the above findings and the reports of the
incompatibility of aromatic rings with nonheme iron mediated
oxidations, some iron-based alcohol oxidation catalysts have
been recently reported to efficiently convert benzylic alcohols
into the corresponding carbonyl compounds.19,23,24,26 However,
competitive aromatic oxidation occurs whenever a high-valent
iron species is clearly implicated in the oxidation
mechanism.45–48,54
2b
58
9
3b
80
5
At this point, a competitive oxidation experiment between
equimolar amounts of the expected more reactive 1-
phenylethanol and cyclohexanol was carried out. Although not
high in absolute value, yield in cyclohexanone (16 %) doubles
the one in acetophenone (8 %). The latter is a very peculiar
feature of catalyst
1
which seems to prefer the oxidation of a
4b
5b
6
65
36
55
6
substrate less activated from both an enthalpic (BDE
α-C-H(OH) = 92.8 and 85.1 kcal/mol for cyclohexanol and 1-
phenylethanol, respectively)42 and polar effects (Scheme 4).
For the sake of comparison, the same competitive experiment
was carried out under the same conditions in the presence of
11
29
complex
4 ([(TPA)Fe(CF3SO3)2], which is known to oxidize
benzyl alcohol.55 In this case the inverse result was obtained,
with cyclohexanone yield being almost half of the
acetophenone one (10 % and 17 %, respectively), in accordance
with BDE-based prediction. The results of the last two
experiments emphasize a very specific character of catalytic
properties of complex
1, but the reasons for this unusual
behavior are not fully disclosed at this stage. Nevertheless one
7
53
68
30
14
8b
aReaction condition as in entry 8 of Table 1. GC conversions and yields defined as
(mol recovered product/mol substrate)×100 and (mol product/mol substrate)
respectively, average of three determinations (error ±2%). Numeric values of
yield and TON coincide. bdihydroxyl derivatives appear in the mass spectra of the
product mixture, see ESI.
Scheme 3
possible explanation for the inversion of selectivity going from
1
to 4 could be ascribed to the lower steric accessibility of the
iron center in the former. A rather sterically encumbered
pentacoordinated oxidizing species is indeed supposed to form
from reaction of
1 with H2O2 thanks to the detach of one of the
pyridyl arm of the complex.39 Such an oxidizing species would
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be more sterically demanding than the one generated by solution, 5.0 μmol) were mixed in a vial at 25°C. Substrate (250
View Article Online
reaction of the tetracoordinated
4
with H2O2. We carried out μmol) and CH3CN were then added up toDaOIt:o1t0a.l10v3o9l/uCm6OeBo0f1978040F
competitive oxidations on 1:1 mixtures of cyclohexanol and 2- μL. A ~0.7 M CH3CN solution of H2O2 (diluted from a 35%
methylcyclohexanol and of cyclohexanol and 2,6- w/w H2O2 commercial solution) was added over 30 minutes by
dimethylcyclohexanol in the presence of complex
4. Such syringe pump under vigorous stirring, and left reacting for
oxidations led to ratios cyclohexanone/2-methylcyclohexanone additional 60 minutes. At this point an internal standard was
0.68 and cyclohexanone/2,6-dimethylcyclohexanone 1.25, added (bibenzyl, 125 μmol) and the reaction mixture was
respectively. Comparison with the related ratios obtained in the filtered over a short pad of SiO2 with 2 mL of AcOEt. The
presence of complex
1, 1.36 and 1.68 (see above), respectively, filtered solution was subjected to GC or evaporated to furnish
points out to a possible steric origin of the selectivity properties the product mixture.
of catalyst
1
.
When the reaction was carried out on 0.5-gram scale, the
filtration was performed with CH2Cl2, and the pure ketone
product was collected after the silica plug.
Conclusions
In conclusion, we carried out a series of aliphatic and benzylic
alcohol oxidations with H2O2 catalyzed by the readily available
complex
1. We obtained moderate-to-good yields in the case of
Acknowledgements
aliphatic secondary alcohols, depending on substrate steric
hindrance. Primary alcohols react sluggishly in comparison Thanks are due to the Ministero dell’Istruzione, dell'Università
with secondary ones, and probably competitive C-H oxidation e della Ricerca (MIUR, PRIN 2010CX2TLM). This work was
reactions takes place. Benzylic alcohols are oxidized only in also partially supported by Università di Roma La Sapienza
low yields, due to competitive aromatic hydroxylation (Progetti di Ricerca 2014). Thanks are also due to the CIRCC,
reactions. Interestingly, in a competitive oxidation experiment, Interuniversity Consortium of Chemical Catalysis and
less reactive cyclohexanol is oxidized preferentially with Reactivity.
respect to 1-phenylethanol. The cause of this unprecedented
selectivity is not fully clear at this stage, and are currently under
investigation in our laboratory.
Notes and references
¶ Complex 1 was previously characterized by means of a series of
techniques including X-ray diffraction, 1H NMR and UV-vis
spectroscopy, elemental analysis, ESI-MS, cyclic voltammetry (see
ref 35 and 39). Complex 1 was shown to have a high stability in
acetonitrile solution even at very low concentrations (UV-vis
titrations, see ref 35). Furthermore, complex 1 was also shown to
be highly stable also in the oxidative reaction conditions by means
of coupled UV-vis and ESI-MS investigations: although it slowly
undergoes oxidative degradation paths during the reaction, remains
the most abundant iron containing species and the most
catalytically active species along large part of the reaction
timecourse (see ref 39).
§ Unreacted alcohol remains on the silica layer.
‡ A comparable decrease of cyclohexanone yield was also observed
when the cyclohexanol oxidation catalyzed by 1 was carried out in
the presence of 10 % mol phenol.
1
2
3
4
5
6
7
J.-E. Backwall, Ed., Modern Oxidation Methods, Wiley-VCH,
Weinheim, Germany, 2010.
R. A. Sheldon and J. K. Kochi, Metal-Catalyzed Oxidations of
Organic Compounds, Academic Press, New York, 1981.
J. M. Hoover and S. S. Stahl, J. Am. Chem. Soc., 2011, 133,
16901–16910.
J. M. Hoover, J. E. Steves and S. S. Stahl, Nat. Protoc., 2012,
7, 1161–1166.
R. Noyori, A. Masao and K. Sato, Chem. Commun., 2003,
1977–1986.
Scheme 4
S. Enthaler, K. Junge and M. Beller, Angew. Chemie - Int.
Ed., 2008, 47, 3317–3321.
K. Chen and L. Que Jr., J. Am. Chem. Soc., 2001, 123, 6327–
37.
Experimental
In a typical oxidation experiment Fe(CF3SO3)2(CH3CN)2 (1.09
mg, 2.50 μmol), picolylamine (from a ~0.1 M CH3CN solution,
5.0 μmol) and picolylaldehyde (from a ~0.1 M CH3CN
This journal is © The Royal Society of Chemistry 20xx
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Page 6 of 7
ARTICLE
Journal Name
8
9
M. S. Chen and M. C. White, Science, 2007, 318, 783–787.
33
34
35
M. Ciaccia and S. Di Stefano, Org. Biomol. Chem., 2015,
View Article Online
646–654.
DOI: 10.1039/C6OB01984F
L. Gómez, I. Garcia-Bosch, A. Company, J. Benet-Buchholz,
A. Polo, X. Sala, X. Ribas and M. Costas, Angew. Chemie -
Int. Ed., 2009, 48, 5720–5723.
Y. Hitomi, K. Arakawa, T. Funabiki and M. Kodera, Angew.
Chemie - Int. Ed., 2012, 51, 3448–52.
G. Olivo, O. Lanzalunga, L. Mandolini and S. Di Stefano, J.
Org. Chem., 2013, 78, 11508–11512.
O. Cussó, X. Ribas and M. Costas, Chem. Commun., 2015,
51, 14285–14298.
G. Olivo, O. Lanzalunga and S. Di Stefano, Adv. Synth.
Catal., 2016, 358, 843–863.
G. Olivo, G. Arancio, L. Mandolini, O. Lanzalunga and S. Di
Stefano, Catal. Sci. Technol., 2014, 4, 2900–2904.
G. Shul’pin, Catalysts, 2016, 6, 50–90.
E. P. Talsi and K. P. Bryliakov, Coord. Chem. Rev., 2012, 256,
1418–1434.
A. C. Lindhorst, S. Haslinger and F. E. Kühn, Chem.
Commun., 2015, 51, 17193–17212.
10
11
12
13
36
37
38
39
C. Zang, Y. Liu, Z.-J. Xu, C.-W. Tse, X. Guan, J. Wei, J.-S.
Huang and C.-M. Che, Angew. Chemie Int. Ed., 2016, 55, 2–
7.
G. Olivo, M. Nardi, D. Vìdal, A. Barbieri, A. Lapi, L. Gómez,
O. Lanzalunga, M. Costas and S. Di Stefano, Inorg. Chem.,
2015, 54, 10141–10152.
14
V. a Yazerski, P. Spannring, D. Gatineau, C. H. M. Woerde,
S. M. Wieclawska, M. Lutz, H. Kleijn and R. J. M. K. Gebbink, 40
Org. Biomol. Chem., 2014, 12, 2062–70.
W. N. Oloo and L. Que Jr., Acc. Chem. Res., 2015, 48, 2612–
2621.
15
16
F. Shi, M. K. Tse and M. Beller, Chem. - An Asian J., 2007, 2,
411–415.
B. Join, K. Möller, C. Ziebart, K. Schröder, D. Gördes, K.
Thurow, A. Spannenberg, K. Junge and M. Beller, Adv.
Synth. Catal., 2011, 353, 3023–3030.
F. Shi, M. K. Tse, M. M. Pohl, A. Brückner, S. Zhang and M.
Beller, Angew. Chemie - Int. Ed., 2007, 46, 8866–8868.
F. Shi, M. K. Tse, Z. Li and M. Beller, Chem. - A Eur. J., 2008,
14, 8793–7.
M. Lenze and E. B. Bauer, Chem. Commun., 2013, 49,
5889–91.
T. Kikuchi and K. Tanaka, Eur. J. Inorg. Chem., 2014, 2014,
607–618.
H. Hosseini-Monfared, C. Näther, H. Winkler and C. Janiak,
Inorg. Chim. Acta, 2012, 391, 75–82.
J. E. Chàvez, C. Crotti, E. Zangrando and E. Farnetti, J. Mol.
Catal. A Chem., 2016, 421, 189–195.
B. Biswas, A. Al-Hunaiti, M. T. Räisänen, S. Ansalone, M.
Leskelä, T. Repo, Y.-T. Chen, H.-L. Tsai, A. D. Naik, A. P.
Railliet, Y. Garcia, R. Ghosh and N. Kole, Eur. J. Inorg.
Chem., 2012, 2012, 4479–4485.
S. Tanaka, Y. Kon, T. Nakashima and K. Sato, RSC Adv.,
2014, 4, 37674.
S. Tanaka, Y. Kon, A. Ogawa, Y. Uesaka, M. Tamura and K.
Sato, ChemCatChem, 2016, 10.1002/cctc.201600362.
P. Shejwalkar, N. P. Rath and E. B. Bauer, Dalton Trans.,
2011, 40, 7617–7631.
P. Saisaha, L. Buettner, M. van der Meer, R. Hage, B. L.
Feringa, W. R. Browne and J. W. de Boer, Adv. Synth.
Catal., 2013, 355, 2591–2603.
J. J. Dong, D. Unjaroen, F. Mecozzi, E. C. Harvey, P. Saisaha,
D. Pijper, J. W. de Boer, P. Alsters, B. L. Feringa and W. R.
Browne, ChemSusChem, 2013, 6, 1774–1778.
D. Shen, C. Miao, D. Xu, C. Xia and W. Sun, Org. Lett., 2015,
17, 54–57.
M. T. Räisänen, A. Al-Hunaiti, E. Atosuo, M. Kemell, M.
Leskelä and T. Repo, Catal. Sci. Technol., 2014, 4, 2564.
M. Ciaccia, R. Cacciapaglia, P. Mencarelli, L. Mandolini and
S. Di Stefano, Chem. Sci., 2013, 4, 2253–2261.
M. Ciaccia, S. Pilati, R. Cacciapaglia, L. Mandolini and S. Di
Stefano, Org. Biomol. Chem., 2014, 12, 3282–3287.
41
42
43
A. D. N. Vaz and M. J. Coon, Biochemistry, 1994, 33, 6442–
6449.
Comprehensive Handbook of Chemical Bond Energies, Luo,
Y.-R., CRC Press, Boca Raton, Florida, USA, 2007.
F. Minisci, F. Recupero, A. Cecchetto, C. Gambarotti, C.
Punta, R. Faletti, R. Paganelli and G. F. Pedulli, European J.
Org. Chem., 2004, 109–119.
C. Annunziatini, M. F. Gerini, O. Lanzalunga and M.
Lucarini, J. Org. Chem., 2004, 69, 3431–3438.
O. V Makhlynets, P. Das, S. Taktak, M. Flook, R. Mas-
Ballesté, E. V Rybak-Akimova and L. Que Jr., Chem. - A Eur.
J., 2009, 15, 13171–80.
N. Y. Oh, M. S. Seo, M. H. Lim, M. B. Consugar, M. J. Park,
J.-U. Rohde, J. Han, K. M. Kim, J. Kim, L. Que Jr. and W.
Nam, Chem. Commun., 2005, 3, 5644–5646.
M. P. Jensen, S. J. Lange, M. P. Mehn, E. L. Que and L. Que
Jr., J. Am. Chem. Soc., 2003, 125, 2113–28.
O. V Makhlynets and E. V Rybak-Akimova, Chem. - A Eur. J.,
2010, 16, 13995–4006.
17
18
19
20
21
22
23
44
45
46
47
48
49
50
A. M. Adams, J. Du Bois and H. A. Malik, Org. Lett., 2015,
17, 6066–6069.
24
25
26
27
A. Barbieri, R. De Carlo Chimienti, T. Del Giacco, S. Di
Stefano, O. Lanzalunga, A. Lapi, M. Mazzonna, G. Olivo and
M. Salamone, J. Org. Chem., 2016, 81, 2513–2520.
K. Nehru, M. S. Seo, J. Kim and W. Nam, Inorg. Chem.,
2007, 46, 293–8.
A. Barbieri, M. De Gennaro, S. Di Stefano, O. Lanzalunga, A.
Lapi, M. Mazzonna, G. Olivo and B. Ticconi, Chem.
Commun., 2015, 51, 5032–5035.
E. Baciocchi, S. Belvedere, M. Bietti and O. Lanzalunga, Eur.
J. Org. Chem., 1998, 299–302.
A. Thibon, V. Jollet, C. Ribal, K. Sénéchal-David, L. Billon, A.
B. Sorokin and F. Banse, Chem. - A Eur. J., 2012, 18, 2715–
24.
51
52
53
54
28
29
30
31
32
55
Y. O. Na, Y. Suh, J. P. Mi, S. S. Mi, J. Kim and W. Nam,
Angew. Chemie - Int. Ed., 2005, 44, 4235–4239.
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Organic & Biomolecular Chemistry
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Journal Name
ARTICLE
Graphical abstract
View Article Online
DOI: 10.1039/C6OB01984F
A cheap and easily available catalyst for alcohol oxidations
with unexpected selectivity features.
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