Pd/Al2O3-catalysed redox isomerisation of allyl alcohol: Application in aldol condensation and oxidative heterocyclization reactions

Article abstract of DOI:10.1039/c5cy01722j

The application of the Pd/Al₂O₃ catalyst in allyl alcohol isomerization and subsequent aldol condensation and heterocyclization reactions is described. The activity of Pd/Al₂O₃ in these transformations is suggested to be due to the participation of the Lewis acidic sites of the support in the activation of the alcohol towards oxidative dehydrogenation by the metal and subsequent hydride transfer. The resulting enol(ate)/aldehyde could undergo further reactions promoted by the acid-base properties of the support. In the aldol condensation reactions of the isomerization product, electron poor aromatic aldehydes and heteroaromatic aldehydes showed the highest activity, while aromatic aldehydes bearing electron donating substituents reacted after transformation to the corresponding N-tosyl imines. 1,2-Disubstituted aromatics gave heterocyclic products in one-pot multistep reaction sequences.

Full text of DOI:10.1039/c5cy01722j

View Article Online
View Journal
Catalysis
Science &
Technology
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: D. Zsolnai, M.
Péter, K. Szri and G. London, Catal. Sci. Technol., 2015, DOI: 10.1039/C5CY01722J.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/catalysis

Please do not adjust margins
Catalysis Science & Technology
Page 1 of 7
View Article Online
DOI: 10.1039/C5CY01722J
Journal Name
ARTICLE
Pd/Al2O3-catalysed redox isomerisation of allyl alcohol:
application in aldol condensation and oxidative heterocyclization
reactions
Received 00th January 20xx,
Accepted 00th January 20xx
Dániel Zsolnai,a Péter Mayer,a Kornél Szőrib and Gábor London*b
DOI: 10.1039/x0xx00000x
The application of Pd/Al2O3 catalyst in allyl alcohol isomerization and subsequent aldol-condensation and heterocyclization
reactions is described. The activity of Pd/Al2O3 in these transformations is suggested to be due to the participation of the
Lewis acidic sites of the support in the activation of the alcohol towards oxidative dehydrogenation by the metal and
subsequent hydride transfer. The resulting enol(ate)/aldehyde could undergo further reactions promoted by the acid-base
properties of the support. In the aldol condensation reactions of the isomerization product electron poor aromatic
aldehydes and heteroaromatic aldehydes showed the highest activity, while aromatic aldehydes bearing electron donating
substituents reacted after transformation to the corresponding N-tosyl imines. 1,2-disubstituted aromatics gave
heterocyclic products in one-pot multistep reaction sequences.
www.rsc.org/
isomerisation chemistry are transition metal complexes;
particularly efficient are Ru and Rh complexes but other metals
from the groups 8, 9 and 10 have been used successfully as
well.4
Introduction
The transition metal catalysed redox isomerization of allylic
alcohols to carbonyl compounds1 (Figure 1a), has been widely
studied not only because of its atom-economical nature2 but
also for its use in tandem isomerisation/C-C or C-heteroatom
bond formation processes.3
Compared to transition metal complexes supported transition
metals are rarely documented as catalysts for isomerisation5-10
and essentially there is no example of combining
heterogeneous transition metal catalysed isomerisation with
C-C or C-heteroatom bond formation processes exists.11 This is
surprising in light of the current efforts of developing one-pot
tandem reactions over heterogeneous catalysts as a means of
environmentally benign organic synthetic methodology.12-20
Strikingly, although Pd is one of the most synthetically useful
catalytic transition metals,21 it is underrepresented in these
Figure 1 Transition metal catalysed redox isomerisation of allyl alcohol (M = Ru, kinds of transformations of allylic alcohols.11,22-33 Pd-catalysed
Rh, Fe, Co, Ni, Mo, Ir, Pt, Os, etc.). The enolate intermediate could either
isomerisation is mostly discussed as a competing reaction of
the double bond hydrogenation process.22-24,26,27,31,32 There
tautomerise to the corresponding saturated carbonyl compound (a) or
sequentially react with an electrophile (E+) to form a new C-C or C-heteroatom
seems to be two main reasons why Pd-catalysis is problematic
bond.
in this context. In one hand, Pd(0) complexes favour to form π-
allyl complexes with allyl alcohol34,35 instead of the insertion
The most extensively studied tandem reactions of allylic
into the O-H bond.36 The other issue is related to the
alcohols are those where these molecules are participating as
formation of a metal-hydride, which has been identified as key
catalytic species in the isomerisation of allylic alcohols.3,4,37
While in the case of metal complexes the hydride can be
present in the form of hydride ligand in the pre-catalyst38-40 or
could form in situ upon oxidation of the allylic alcohol
used,1,41,42 for supported Pd23,24,26,27 or alkylthiol stabilized Pd
the corresponding enols/enolates (aldol and Mannich
reactions, electrophilic fluorinations, etc.) produced via
transition-metal catalysed double bond isomerisation (Figure
1b). The majority of the catalysts developed for the
a.Department of Organic Chemistry, University of Szeged, Dóm tér 8, H-6720
Szeged, Hungary.
nanoparticles28-30
a H2 atmosphere is described to be
b.MTA-SZTE Stereochemistry Research Group, Dóm tér 8, H-6720 Szeged, Hungary.
Email: londong@chem.u-szeged.hu
necessary for the isomerisation to proceed. In fact, some
authors state that in the absence of hydrogen no reaction
occurred.22,23,26 The presence of H2, however, can be
responsible for lowering the product selectivity due to the
†Electronic Supplementary Information (ESI) available: The effect of other Pd-
sources, control experiments with propionaldehyde and acrolein, synthesis and
characterisation and NMR spectra of compounds presented in this article.
DOI: 10.1039/x0xx00000x
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 2 of 7
View Article Online
DOI: 10.1039/C5CY01722J
Journal Name
ARTICLE
Figure 1 (a) Cooperative oxidative dehydrogenation of alcohols over Al2O3-supported transition metals; (b) Isomerisation of allyl alcohol to the corresponding enol(ate) over
Pd/Al2O3.
Table 1 Optimisation of Pd/Al2O3 catalysed allyl alcohol isomerisation/aldol
condensation sequence.a
competing hydrogenation process leading to the
corresponding saturated alcohol and could potentially
interfere with additional catalytic steps. Therefore, extensive
optimization is necessary for maximising the selectivity of the
required isomerisation product.
Building on the design of Shimizu and co-workers using Al2O3-
supported transition metals for cooperative oxidative
Entry
1
Solvent
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
H2O
Additive
-
Yield (%)b
38
dehydrogenation of alkyl and cycloalkyl alcohols43-45 (Fig. 2. a)
we envisioned that the M-H species forming during the
process could participate in a conjugate reduction of oxidised
allyl alcohol (acrolein) that would lead to enol(ate) formation
(Fig. 2. b). Thus, the isomerisation of allyl alcohol could be
realised on supported transition metal catalyst and the
resulting enol(ate) could be involved in further one-pot
reactions.
2
K2CO3 (1 eq)
K2CO3 (2 eq)
K2CO3 (1 eq)
K2CO3 (1 eq)
MgSO4 (1 eq)
4Å mol. sieves
NaOAc (1 eq)
KOtBu (1 eq)
Et3N (1 eq)
K2CO3 (1 eq)
45
3
40
4c
44
5d
7
28
Here we report the Pd/Al2O3-catalysed isomerisation of allyl
alcohol and the subsequent one-pot transformation of the
isomerisation products in aldol condensation and
heterocyclization reactions without added H2 gas. We suggest
that the synergistic activation of the alcohol reactant by the
Lewis-acidic sites of the Al2O3 support and the Pd metal is key
for the reactions to occur.
35
8
29
9
25
10
11
12
13
14
15
16e
mixture
15
RESULTS AND DISCUSSION
<5
The optimization of the reaction conditions to isomerise allyl
alcohol to the corresponding enol(ate) over Pd/Al2O3 and
involve it in aldol chemistry with 4-nitrobenzaldehyde are
shown in Table 1. In line with our expectations, Pd/Al2O3 alone
proved to be an active catalyst for both the isomerisation and
the condensation steps. Other Pd-based catalysts (Pd(II) salts,
Pd/CaCO3, Pd/BaSO4, Pd/SiO2, Pd/C, Pd/CeO2) failed to
catalyse the reaction or delivered minor amount of
condensation product (for more details and control
experiments, see sections S2 and S3 of the ESI). The isolated
yields could be further increased with the addition of 1 eq
K2CO3 (Table 1, entry 2), however, increasing the amount of
the carbonate did not considerably affect the yield.
1,4-dioxane K2CO3 (1 eq)
19
DMSO
DMF
K2CO3 (1 eq)
K2CO3 (1 eq)
K2CO3 (1 eq)
<5
<5
toluene
26
a
Reaction conditions: 0.5 mmol 4-nitrobenzaldehyde, 1 mmol allyl alcohol, 1 mL
toluene, 5 mol% Pd of a given source, additive, 100°C, 24 h. b Isolated yield of the
aldol condensation product. c The reaction was performed under N2 atmosphere.
d The reaction was performed at 50°C. e The catalyst was pre-treated: 90 min in H2
flow (30 mL/min) at 200°C then 30 min at He flow (30 mL) at rt.
In order to test the role of the K2CO3 additive, weather it is a
base or a drying agent to eliminate the water forms during the
condensation step, we performed the reaction in the presence
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 2
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 3 of 7
View Article Online
DOI: 10.1039/C5CY01722J
Journal Name
ARTICLE
of MgSO4 and 4Å molecular sieves (Table 1, entries 7, 8). As
the results with these additives are similar to those obtained
without any additive, we conclude that K2CO3 is rather has a
role as a base. It could participate in the alcohol deprotonation
and in the aldol condensation step complementing the effect
of the support material. It has to be noted, that using Al2O3
alone did not lead to product formation, furthermore under
Pd/Al2O3 catalysis we detected the formation of some 2-
methyl-2-pentenal from the self-aldol condensation of
propanal as a side-product. We also tested other bases (1 eq)
in combination with Pd/Al2O3 (Table 1, entries 9-11). Using
NaOAc gave a decreased yield of 25%, while in the case of
KOtBu a complex mixture of products were formed. Et3N was
not beneficial either as only 15% isolated yield was obtained in
this case.
Figure 2 Effect of allyl alcohol excess on the reaction of 4-nitrobenzaldehyde with allyl
alcohol. (Reaction conditions: 0.5 mmol aldehyde, 1 mL toluene, 5 mol% Pd (source: 5
% Pd/Al2O3), 0.5 mmol K2CO3, 100°C, 24 h.)
Table 2 Reactivity of different aldehydes in the Pd/Al2O3 catalysed isomerisation/aldol
condensation sequence.a
Using more polar solvents gave generally lower yields
compared to toluene (Table 1, entries 12-15). Moreover, in
such solvents we observed the formation (up to 10%) of the
decarbonylated product nitrobenzene and also benzaldehyde
upon loss of the NO2-group. The formation of inactive carbonyl
complexes could contribute to catalyst deactivation under
such conditions.
Entry
Aldehyde
Product
Yield (%)b
Performing the reaction without the exclusion of air or under
N2 atmosphere did not significantly affect the outcome (Table
1, entry 2 vs 4), however, reductive pre-treatment (H2, 200°C)
of the catalyst led to decreased yield (Table 1, entry 16). This
result is in agreement with previous findings on the nature of
active sites in heterogeneous Pd-catalysed selective oxidation
of allylic alcohols. It has been shown that the presence of
higher oxidation state surface environments is necessary for
the oxidative dehydrogenation to proceed efficiently.46-48
Particularly, the Pd-O-Al surface structures47 at the perimeter
of the metal particles likely have an important role in the
activation of the allyl alcohol towards isomerisation that could
be destroyed during the reductive pre-treatment. The
formation of such metal-support contacts has been observed
for Pt-based catalysts49,50 and suggested for Pd/Al2O3 as
well.47,51
O
O
1
20
NO2
NO2
O
2
3
67 (45)c
O
O
O
58
As a comparison we tested 5% Pt/Al2O3 (Engelhard 4759) also,
however, over this catalyst no condensation product was
isolated. Instead, apart from unreacted aldehyde, we detected
the formation of (4-nitrophenyl)methanol, the reduced
derivative of 4-nitrobenzaldehyde as the only product, which is
likely the result of a transfer-hydrogenation reaction, allyl
alcohol being the hydrogen source. The different reactivity of
the Pt and Pd systems could be based on the different stability
of the forming M-H species36 that is involved in the next step
of the catalytic cycle. Pt-H being more stable, reacts only with
the carbonyl carbon of the aromatic aldehyde that carries
more positive charge relative to the β-carbon of acrolein.
The influence of allyl alcohol excess in the reaction of 4-
nitrobenzaldehyde and allyl alcohol was studied in order to
increase the isolated yield of the aldol condensation product
(Fig. 3.). However, we found that the alcohol has a poisoning
effect as increasing its amount led to decreased yields.
4d
50
5d
6d
7
54
26
8
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 4 of 7
View Article Online
DOI: 10.1039/C5CY01722J
Journal Name
ARTICLE
O
8
traces
3
32
N
a
Reaction conditions: 0.5 mmol aldehyde, 1 mmol allyl alcohol, 1 mL toluene, 5 mol%
b
Pd (source: 5 % Pd/Al2O3), 0.5 mmol K2CO3, 100°C, 24 h. Isolated yield of the aldol
c
d
condensation product. Isolated yield without K2CO3 additive. Reaction time was 48
h.
4
50
a
Reaction conditions: 0.5 mmol N-tosyl imine, 1 mmol allyl alcohol, 1 mL toluene, 5
A possible reason for such an effect is the competitive
interaction of allyl alcohol (or the isomerisation product
propionaldehyde) with the Lewis acidic sites of the support
that hinders the activation of the aromatic aldehyde towards
the aldol condensation step. Similar effect of reactant excess
in Lewis acidic zeolite catalysed aldol condensation has been
recently reported.52
b
mol% Pd (source: 5 % Pd/Al2O3), 0.5 mmol K2CO3, 100°C, 24 h. Isolated yield of the
aldol condensation product.
We also examined the reusability of the catalyst in the reaction
of 4-cyanobenzaldehyde with allyl alcohol (Table 4). After a
reaction was performed we filtered the catalyst, washed with
EtOAc and Et2O, dried and used in the next reaction. The
catalyst remained active in four consecutive reactions,
although the activity decreased considerably. This could be
due to the formation of polymeric side products that could not
be washed off the surface of the catalyst. We also tested the
potential contribution of dissolved active catalyst. We found
no increment in the conversion after filtering the catalyst at 3
h reaction time from the reaction mixture and heated the
solution further until the 24 h reaction time was complete (see
also ESI).
Other aldehyde substrates were also tested under the
Pd/Al2O3/K2CO3 conditions. In the case of aromatic aldehydes
with electron withdrawing groups and heteroaromatic
aldehydes we obtained the aldol condensation products in
moderate to good yields (Table 2). However, aliphatic
aldehydes and aromatic aldehydes bearing electron donating
groups did not undergo reaction. Products from such
aldehydes would be desirable as those are precursors to
flavour and fragrance compounds (such as lilial or canthoxal
that contain 4-tert-butylphenyl and 4-methoxyphenyl groups,
respectively; Table 3, entries 2 and 4).
Table 4 Catalyst recycling study in the reaction of 4-cyanobenzaldehyde with allyl
alcohol over Pd/Al2O3 catalyst.a
Entry
Cycle
Time (h)
24
Yield (%)b
We transformed the aromatic aldehydes with electron
donating groups to the corresponding N-tosyl imines in order
to activate them towards reaction with the enolate. This
transformation was proved to be successful in terms of
reactivity, however, it also raised some difficulties. The
eliminated sulphonamide participated in side reactions, such
as reaction with the product aldehyde that made the
purification tedious in some cases.
1
2
3
4
1
2
3
4
58
38
35
12
24
24
Table 3 Reactivity of N-tosyl imine derivatives of electron rich aromatic aldehydes in
the Pd/Al2O3 catalysed isomerisation/aldol condensation sequence.a
48
a
Reaction conditions: 0.5 mmol aldehyde, 1 mmol allyl alcohol, 1 mL toluene, 5 mol%
b
Pd (source:
5 % Pd/Al2O3), 0.5 mmol K2CO3, 100°C. Isolated yield of the aldol
condensation product.
To further increase the structural diversity accessible with the
allyl alcohol/supported Pd system we examined 1,2-
disubstituted aromatics under the reaction conditions. We
speculated that after the first, aldol condensation (or imine
formation) step ring-closing reactions might be feasible to
obtain heterocycles. We studied the reaction of
salicylaldehyde and ortho-substituted anilines with allyl
alcohol.
Entry
1
N-tosyl imine
Product
Yield (%)b
25
O
As we envisioned, ring closing occurred in the reaction of
salicylaldehyde, however, the reaction did not stop in the
lactol stage, but proceeded further with an oxidation step that
delivered 3-methylcoumarine as the overall product (Fig. 4.).
We also compared the activity of Pd/C and Pd/Al2O3 catalyst in
this reaction. Similarly as in the aldol chemistry the Pd/Al2O3
system outperformed Pd/C.
2
59
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 4
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 5 of 7
View Article Online
DOI: 10.1039/C5CY01722J
Journal Name
ARTICLE
Similarly as for o-phenylenediamine, the added base
decreased the selectivity somewhat. The reaction of 2-
aminophenol resulted in the formation of a complex mixture
with only traces of the expected benzoxazole derivative. The
mixture also contained the imine and minor amount of O- and
N-allylation products.
For the occurrence of both the aldol condensation reactions
and ring formations described above the isomerisation of allyl
alcohol is prerequisite. As all the reactions studied took place
more efficiently when Pd/Al2O3 was used as a catalyst, we
propose a metal/support cooperativity that operates under
the reaction conditions (Fig. 7). Such cooperativity has been
described in heterogeneous alcohol oxidation chemistry43-
45,53,54 but unprecedented in isomerisation reactions.
Figure
3 Supported Pd-catalysed one-pot isomerisation/aldol condensation/lactol
formation/dehydrogenation cascade reaction of allyl alcohol with salicyladehyde.
We considered o-phenylenediamine as an interesting
substrate, as in this case not the nucleophilic enolate but the
electrophilic carbonyl reactivity was necessary for any reaction
to occur (Fig. 5). However, when the reaction was performed
under basic (K2CO3, 1 eq.) conditions a mixture of products
were formed, with the diimine as the main component.
Nevertheless, we detected 2-ethylbenzimidazole in the
product mixture that already suggested a second oxidation
step during the process. Importantly, without added base the
benzimidazole derivative was isolated as the main product.
Interestingly, Pd/C was also active in this transformation, likely
due to the basicity of the aniline nitrogen that was comparably
beneficial as K2CO3 in the aldol condensation reactions. Using 3
eq of alcohol resulted in 6% increment of the isolated yield
with Pd/Al2O3 catalyst.
We propose that the key for the isomerisation to occur is the
coordination of the alcohol to a Lewis-acidic Al-site adjacent to
Pd-particles (Fig. 7, step 1), which is positioning and activating
the alcohol towards the oxidative dehydrogenation step
catalysed by the metal. This process is further supported by
the affinity of the double bond to the Pd. After the
dehydrogenation takes place and the metal hydride forms, the
product acrolein either stays coordinated to the support (step
2b) or decoordinates (step 2) and coordinates again in a next
step (step 3). In any case, a hydride transfer follows that yields
the enolate (step 4) that tautomerises to the corresponding
saturated aldehyde (step 5). We performed control
experiments with allyl acetate and acrolein to show that both
the O-H proton and the α-proton adjacent to the OH group are
necessary to be present for the isomerisation. In fact, the use
of these reagents did not lead to product formation in the
reaction with 4-nitrobenzaldehyde. (For further control
experiments, see section S3 of the ESI.) The participation of
the Lewis-acidic Al-sites is also supported by the poor results
when bases that are able to block these centres (KOtBu, Et3N)
were used. On the other hand, the role of framework oxygens
in Al2O3 as basic sites45,52 was tested with the addition of
CH3COOH to the reaction mixture. Upon addition of 25 mol%
acid resulted in a decrease in the isolated yield (25% with acid
vs. 38% without any additive) of the condensation product.
These together suggest the importance of both acidic and
basic sites of the support material in the overall
transformation.
Figure
4 Supported Pd-catalysed one-pot isomerisation/imine formation/ring
closing/dehydrogenation cascade reaction of allyl alcohol with o-phenylenediamine.
The reactivity of 2-aminothiophenol and 2-aminophenol was
also tested under the reaction conditions. In the former case
the oxidative formation of the corresponding disulphide was
faster than the isomerization/imine formation/ring closing
sequence and we isolated the disulphide in high yield (Fig. 6.).
It is noted that the allyl alcohol is not necessary for this
transformation, as we obtained the same result when the
reaction was repeated without the alcohol.
Figure
5 2-aminothiophenol formed the corresponding disulphide instead of the
benzothiazole derivative under the reaction conditions.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 6 of 7
View Article Online
DOI: 10.1039/C5CY01722J
Journal Name
ARTICLE
layer chromatography was carried out on SiO2–layered aluminium
plates (60778-25EA, Fluka). Flash column chromatography was
performed using SiO2–60 (230–400 mesh ASTM, 0.040–0.063 mm
Support/metal synergism
- positioning
- activation
Pd
Al
H
1
from Merck) at 25 °C. H NMR and 13C NMR spectra were recorded
O
on a Bruker AVANCE DRX 400 spectrometer. Mass spectra (MS) of
the products were recorded on an Agilent 6890N-5973 GC-MSD. For
further details on the synthesis and characterization of the products
presented in this article, see ESI.
H
H
O
O
O
OH
Al
OH
Al
Al
O
Al
O
O
General procedure for the isomerization/aldol condensation
sequence: The aldehyde or N-tosyl imine (0.5 mmol), 5% Pd/Al2O3 (5
mol% Pd, 53 mg), K2CO3 (0.5 mmol) were suspended in toluene (1
mL) and subsequently allyl alcohol was added (1 mmol). The
mixture was heated at 100°C for 24 h then filtered. The residue was
washed several times with EtOAc. The organic phase was
concentrated and purified by flash column chromatography.
step 1
O
H
OH
H
O
step 5
step 2
step 2b
H
H
OH
Al
O
OH
Al
Al
O
O
O
Al
O
O
step 4
Acknowledgements
step 3
H
Financial support from the National Research, Development
and Innovation Office, Hungary (OTKA Grants K 109278 and PD
115436) is gratefully acknowledged. V. Pilán, and Z. Szécsényi
(Institute of Pharmaceutical Chemistry, University of Szeged)
and M. Tóth and K. Baán (Department of Physical Chemistry
and Materials Science, University of Szeged) are acknowledged
for technical support and useful discussions.
O
OH
Al
Al
O
O
Figure 6 Proposed mechanism for the isomerisation of allyl alcohol over Pd/Al2O3
involving support/metal synergism.
Conclusions
Alumina supported Pd was found to be an active catalyst in
allyl alcohol isomerization which transformation was combined
with aldol condensation and heterocyclic ring formation
reactions one-pot. The activation of the alcohol by the alumina
towards oxidative dehydrogenation by the metal and the
subsequent hydride-transfer resulted in the overall
isomerization reaction without the need of added H2 gas. The
acid-base properties of the support material also allowed for
subsequent aldol condensation and imine formation reactions
one-pot, yielding α,β-unsaturated aldehydes and heterocyclic
compounds, thus, providing considerable structural diversity
Notes and references
1
B. M. Trost and R. J. Kulawiec, Tetrahedron Lett. 1991, 32
3039‒3042.
B. M. Trost, Science 1991, 254, 1471‒1477.
N. Ahlsten, A. Bartoszewicz and B. Martín-Matute, Dalton
Trans., 2012, 41, 1660‒1670.
R. C. van der Drift, E. Bouwman and E. Drent, J. Organomet.
,
2
3
4
5
Chem., 2002, 4, 870‒891.
C. M. Standfest-Hauser, T. Lummerstorfer, R. Schmid, K.
Kirchner, H. Hoffmann and M. Puchberger, Monatsh. Chem.,
2003, 134, 1167‒1175.
6
7
8
9
K. Yamaguchi, T. Koike, M. Kotani, M. Matsushita, S. Shinachi
and N. Mizuno, Chem. Eur. J., 2005, 11, 6574‒6582.
J. W. Kim, T. Koike, M. Kotani, K. Yamaguchi and N. Mizuno,
Chem. Eur. J., 2008, 14, 4104‒4109.
accessible using
a simple catalyst/reactant system. The
described reaction sequences open up new possibilities in the
Pd-catalysed chemistry of allyl alcohols and could be
integrated into more complex one-pot reactions in the future.
S. E. Garcia-Garrido, J. Francos, V. Cadierno, J.-M. Basset and
V. Polshettiwar, ChemSusChem, 2011,
S. Sahoo, H. Lundberg, M. Edén, N. Ahlsten, W. Wan, X. Zou
and B. Martín-Matute, ChemCatChem, 2012, , 243‒250.
4, 104‒111.
4
10 L. Menéndez-Rodriguez, P. Crochet and V. Cadierno, J. Mol.
Catal. A: Chem., 2013, 366, 390‒399.
Experimental
11 Apart from an identified side-reaction in the hydrogenation
of 2-butene-1,4-diol where 2-hydroxytetrahydrofurane
forms through an isomerization/ring closing sequence: M.G.
Musolino, C. M. S. Cutrupi, A. Donato, D. Pietropaolo and R.
Pietropaolo, J. Mol. Catal. A: Chem., 2003, 195, 147‒157.
Commercial reagents, solvents and catalysts (Aldrich, Alfa Aesar,
Fluka, VWR) were purchased as reagent–grade and used without
further purification. 5% Pd/Al2O3 was Engelhard 40692 type.
Pd/CeO2 was prepared according to a literature procedure.55
Catalysts were used without any pre-treatment or otherwise
noticed. Reactions were performed in a screw cap vial without the
exclusion of air or otherwise noticed. Solvents for extraction or
column chromatography were of technical quality. Organic
solutions were concentrated by rotary evaporation at 25-40 °C. Thin
12 F.-X. Felpin and E. Fouquet, ChemSusChem, 2008,
718‒724.
1,
13 E. Gianotti; U. Diaz, A. Velty and A. Corma, Catal. Sci.
Technol., 2013, , 2677‒2688.
14 J. M. Fraile, N. Garcia, C. I. Herrerias and J. A. Mayoral, Catal.
Sci. Technol., 2013, , 436‒443.
15 M. J. Climent, A. Corma, S. Iborra and M. J. Sabater, ACS
Catal., 2014, , 870‒891.
3
3
4
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 6
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 7 of 7
View Article Online
DOI: 10.1039/C5CY01722J
Journal Name
ARTICLE
16 T. Tsubogo, H. Oyamada and S. Kobayashi, Nature, 2015,
520, 329‒332.
17 J. Dijkmans, M. Dusselier, D. Gabriels, K. Houthoofd, P. C. M.
M. Magusin, S. Huang, Y. Pontikes, M. Trekels, A. Vantomme,
L. Giebeler, S. Oswald and B. F. Sels, ACS Catal., 2015, 5,
48 S. F. J. Hackett, R. M. Brydson, M. H. Gass, I. Harvey, A. D.
Newman, K. Wilson and A. F. Lee, Angew. Chem. Int. Ed.,
2007, 46, 8593‒8596.
49 S. D. Jackson, J. Willis, G. D. McLellan, G. Webb, M. B. T.
Keegan, R. B. Moyes, S. Simpson, P. B. Wells and R. Whyman,
J. Catal., 1993, 139, 191‒206.
928‒940.
18 G. Szőllősi, L. Kovács and Z. Makra, Catal. Sci. Technol., 2015,
, 697‒704.
50 A. Goguet, M. Aouine, F. J. Cadete Santos Aires, A. De
,
5
Mallmann, D. Schweich and J. P. Candy, J. Catal., 2002, 209
135‒144.
19 S. Van de Vyver and Y. Román-Leshkov, Angew. Chem. Int.
Ed. 2015, 54, 12554‒12561.
51 E. Lesage-Rosenberg, G. Vlaic, H. Dexpert, P. Lagarde and E.
Freund, Appl. Catal. A: General, 1986, 22, 211-219.
52 J. D. Lewis, S. Van de Vyver and Y. Román-Leshkov, Angew.
Chem. Int. Ed., 2015, 54, 9835‒9838.
53 A. Abad, P. Concepción, A. Corma and H. García, Angew.
Chem. Int. Ed., 2005, 44, 4066‒4069.
54 Y.-B. Huang, M. Shen, X. Wang, P.-C. Shi, H. Li and R. Cao, J.
Catal., 2015, 330, 452‒457.
55 A. Erdőhelyi, J. Raskó, T. Kecskés, M. Tóth, M. Dömök and K
Baán, Catal. Today, 2006, 116, 367‒376.
20 T. Yatabe, X. Jin, K. Yamaguchi and N. Mizuno, Angew. Chem.
Int. Ed., 2015, 54, 13302‒13306.
21 J. Tsuji (ed.) Palladium for Organic Synthesis, Springer Berlin
Heidelberg, 2005.
22 L. K. Freidlin, Y. A. Kopyttsev and N. M. Nazarova, Izv. Akad.
Nauk SSSR, Ser. Khim., 1973, 3, 700‒701.
23 A. K. Zharmagambetova, E. E. Ergozhin, Y. L. Sheludyakov, S.
G. Mukhamedzhanova, I. A. Kurmanbayeva, B. A. Selenova
and B. A. Utkelov, J. Mol. Catal. A: Chem., 2001, 177
,
165‒170.
24 M. G. Musolino, C. M. S. Cutrupi, A. Donato, D. Pietropaolo
and R. Pietropaolo, Appl. Catal. A: General, 2003, 243
333‒346.
,
25 B. Ganchegui, S. Bouquillon, F. Hénin and J. Muzart, J. Mol.
Catal. A: Chem., 2004, 214, 65‒69.
26 M. G. Musolino, P. De Maio, A. Donato and R. Pietropaolo, J.
Mol. Catal. A: Chem., 2004, 208, 219‒224.
27 M. G. Musolino, C. V. Caia, F. Mauriello and R. Pietropaolo,
Appl. Catal. A: General, 2010, 390, 141‒147.
28 E. Sadeghmoghaddam, C. Lam, D. Choi and Y.-S. Shon, J.
Mater. Chem., 2011, 21, 307‒312.
29 E. Sadeghmoghaddam, K. Gaieb and Y.-S. Shon, Appl. Catal.
A: General, 2011, 405, 137‒141.
30 D. J. Gavia and Y.-S. Shon, Langmuir, 2012, 28, 14502-14508.
31 E. Sadeghmoghaddam, H. Gu and Y.-S. Shon, ACS Catal.,
2012,
32 M. Moreno, L. N. Kissell, J. B. Jasinski and F. P. Zamborini,
ACS Catal., 2012, , 2602‒2613.
33 D. J. Gavia, J. Koeppen, E. Sadeghmoghaddam and Y.-S. Shon,
RSC. Adv., 2013, , 13642‒13645.
2, 1838‒1845.
2
3
34 D. E. Bergbreiter and D. A. Weatherford, J. Chem. Soc., Chem.
Commun., 1989, 883‒884.
35 J. Muzart, Tetrahedron, 2005, 714, 4179‒4212.
36 V. V. Grushin, Chem. Rev., 1996, 96, 2011‒2033.
37 A. Varela-Álvarez, J. A. Sordo, E. Piedra, N. Nebra, V.
Cadierno and J. Gimeno, Chem. Eur. J., 2011, 17
,
10583‒10599.
38 L. Mantilli and C. Mazet, Tetrahedron Lett., 2009, 50
4141‒4144.
,
39 L. Mantilli, D. Gerard, S. Torche, C. Besnard and C. Mazet
Angew. Chem. Int. Ed., 2009, 48, 5143‒5147.
40 L. Mantilli, D. Gerard, S. Torche, C. Besnard and C. Mazet
Chem. Eur. J., 2010, 16, 12736‒12745.
41 B. Martín-Matute, K. Bogár, M. Edin, F. B. Kaynak and J.-E.
Bäckvall, Chem. Eur. J., 2005, 11, 5832‒5842.
42 D. Cuperly, J. Petrignet, C. Crévisy and R. Grée, Chem. Eur. J.,
2006, 12, 3261‒3274.
43 K.-i. Shimizu, K. Sugino, K. Sawabe and A. Satsuma, Chem.
Eur. J., 2009, 15, 2341‒2351.
44 K.-i. Shimizu, K. Kon, K. Shimura and S. S. M. A. Hakim, J.
Catal., 2013, 300, 242‒250.
45 K. Kon, S. M .A. H. Siddiki and K.-i. Shimizu, J. Catal., 2013,
304, 63‒71.
46 A. F. Lee and K. Wilson, Green Chem., 2004,
47 A. F. Lee, S. F. J. Hackett, J. S. J. Hargreaves and K. Wilson,
Green Chem., 2006, , 549‒555.
6, 37‒42.
8
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
Please do not adjust margins