Two sides of the same amino acid - Development of a tandem aldol condensation/epoxidation by using the synergy of different catalytic centres in amino acids

Article abstract of DOI:10.1016/j.apcata.2015.10.018

A new tandem catalysis was set up after intensive investigations regarding the amino catalysed aldol condensation and epoxidation. 20 proteinogenic amino acids were investigated as organocatalysts in the epoxidation of an α-branched α,β-unsaturated aldehyde. The most active amino acids were chosen for the optimization of the reaction conditions obtaining excellent yields in the epoxidation. With these insights the first tandem aldol condensation/epoxidation was developed gaining very good yields of the epoxy aldehyde, which was obtained directly from butanal without any purification or isolation of the intermediate. Applying butanal as substrate, which is produced on a large industrial scale, opens up new horizons for novel useful and reactive products. Furthermore, the beneficial influence of lysine and arginine was proven and it was revealed that these amino acids bear two different catalytic centres, which have impact on the synergy in this new tandem catalysis being active within two different reaction mechanisms. The α-amino function catalyses the aldol condensation and the corresponding side chain group is responsible for the catalytically conversion in the epoxidation.

Full text of DOI:10.1016/j.apcata.2015.10.018

Applied Catalysis A: General 509 (2016) 1–7
Contents lists available at ScienceDirect
Applied Catalysis A: General
journal homepage: www.elsevier.com/locate/apcata
Two sides of the same amino acid—development of a tandem aldol
condensation/epoxidation by using the synergy of different catalytic
centres in amino acids
Karoline A. Ostrowski, Dominik Lichte, Michael Terhorst, Andreas J. Vorholt∗
Department of Bio- and Chemical Engineering, TU Dortmund, 44227 Dortmund, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
A new tandem catalysis was set up after intensive investigations regarding the amino catalysed aldol
condensation and epoxidation. 20 proteinogenic amino acids were investigated as organocatalysts in
the epoxidation of an ␣-branched ␣,␤-unsaturated aldehyde. The most active amino acids were chosen
for the optimization of the reaction conditions obtaining excellent yields in the epoxidation. With these
insights the first tandem aldol condensation/epoxidation was developed gaining very good yields of
the epoxy aldehyde, which was obtained directly from butanal without any purification or isolation of
the intermediate. Applying butanal as substrate, which is produced on a large industrial scale, opens
up new horizons for novel useful and reactive products. Furthermore, the beneficial influence of lysine
and arginine was proven and it was revealed that these amino acids bear two different catalytic centres,
which have impact on the synergy in this new tandem catalysis being active within two different reaction
mechanisms. The ␣-amino function catalyses the aldol condensation and the corresponding side chain
group is responsible for the catalytically conversion in the epoxidation.
Received 24 August 2015
Received in revised form 12 October 2015
Accepted 13 October 2015
Keywords:
Epoxidation
Aldol condensation
Tandem catalysis
Amino acid
Aldehyde
© 2015 Elsevier B.V. All rights reserved.
1. Introduction
In general, ␣,␤-unsaturated aldehydes represent reactive inter-
mediates, which can be functionalised in ␣-/ ␤-/ or ␥-position by
Tandem catalyses describe the merge of different catalytic
reactions in one vessel. Therefore, the resulting intermediate is
immediately converted into the desired product, without any iso-
lation or purification steps [1]. Thereby, resources can be saved
consuming less solvents, energy and time during the whole process.
These are important requirements for developing reactions, which
fit in the concept of green chemistry besides e.g. the application of
benign reagents [2].
enamine, iminium or dienamine catalysis [5]. The epoxidation of
␣,␤-unsaturated aldehydes as one example is described by iminium
catalysis. In 2005, the first organocatalysed epoxidation of ␣,␤-
unsaturated aldehydes was developed yielding epoxy aldehydes
[6].
Since then, different synthetic organocatalysts were applied in
the epoxidation of ␣,␤-unsaturated aldehydes and ketones with a
main focus on reaching high enantioselectivities [7].
The development of new tandem catalyses is quite challeng-
ing, since the compatibility between different catalyses is not
given automatically. An intermediate with reactive functionali-
ties is often the key in developing new tandem catalyses. Hence,
probably the most developed tandem catalyses contain a hydro-
formylation step resulting in aldehydes as reactive intermediates,
which are easily converted in an organocatalysis [3].
The organocatalysed conversion of aldehydes in homo aldol
condensations yields ␣,␤-unsaturated aldehydes, which can be
catalysed with benign and natural occurring organocatalysts, e.g.
amino acids [4].
The use of amino acids as organocatalysts in epoxidations is
only described once [7b]. Therein, 30 mol% proline is not active in
the epoxidation of cinnamic aldehyde, if applied solely. The fur-
ther addition of 80 mol% triethylamine yields 79% desired epoxy
aldehyde.
The homo aldol condensation of propionaldehyde and higher
aldehydes (with longer carbon chains), leads to ␣,␤-unsaturated
aldehydes with an ␣-branching. Only scattered examples are deal-
ing with the epoxidation of these bulky substrates, [7e,8] including
the epoxidation of trisubstituted double bonds [9].
Recently, we investigated the amino acid (AS) catalysed homo
aldol condensation of aldehydes obtaining ␣,␤-unsaturated alde-
hydes in a simple reaction system with excellent yields within short
reaction times [10]. This reaction system consisted of three sub-
stances: the aldehyde, the amino acid and a solvent. We achieved
∗
Corresponding author. Fax: +49 231 755 2311.
E-mail address: andreas.vorholt@bci.tu-dortmund.de (A.J. Vorholt).
http://dx.doi.org/10.1016/j.apcata.2015.10.018
0926-860X/© 2015 Elsevier B.V. All rights reserved.

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K.A. Ostrowski et al. / Applied Catalysis A: General 509 (2016) 1–7
Fig. 1. Yield over catalyst concentration plot of cysteine, tryptophan, glycine and methionine; Conditions: Conditions: 3 mmol 2, amino acid, 1.1 eq H2O2 (35% in water),
1 mL EtOH, r.t., 16 h.
catalysed with only one catalyst without isolation or purification
of the intermediate (Scheme 1). In this way, reactive intermediates
can be synthesized in one tandem catalysis, which are easily acces-
sible directly from aldehydes such as butanal (1) with water as the
only by product.
2. Experimental
Scheme 1. Tandem aldol condensation/epoxidation catalysed by proteinogenic
amino acids.
Detailed experimental procedures are available in the Support-
ing information.
high yields (up to 99%) with low catalyst amounts (3.33–6.67 mol%)
in short reaction times (1–3 h).
3. Results & discussion
In this publication, we apply the aldol condensation product of
butanal, which bears a branching at the ␣-carbon atom, as start-
ing material for the epoxidation with amino acids. Then, we use
our gained experiences regarding the aldol condensation [10] and
the epoxidation for the development of a new tandem aldol con-
densation/epoxidation which is catalysed by amino acids using an
aqueous hydrogen peroxide solution. This tandem catalysis leads
from the aldehyde 1 over the ␣,␤-unsaturated aldehyde 2 as inter-
mediate directly to the epoxy aldehyde 3. Both reaction steps are
First, we set our focus on the epoxidation of the commercially
available 2-ethylhex-2-enal (2) with proteinogenic amino acids
(AS) as organocatalysts (Scheme 2). This ␣,␤-unsaturated alde-
hyde has a worldwide production of 3.3 million tons per year
and can be easily synthesized by the homo aldol condensation
of butanal (1), wherefore we chose this unsaturated aldehyde as
model substrate, being attractive for the synthesis of the reac-
tive epoxy aldehyde 3. These epoxidation investigations enable the
application of the gained experience from our previous investiga-
Fig. 2. Yield over catalyst concentration plot of basic amino acids; Conditions: 3 mmol 2, amino acid, 1.1 eq H2O2 (35% in water), 1 mL EtOH, r.t., 16 h.

K.A. Ostrowski et al. / Applied Catalysis A: General 509 (2016) 1–7
3
Fig. 3. Summary of the results after the systematic investigation applying 20 proteinogenic amino acids; Conditions: 3 mmol 2, amino acid, 1.1 eq H2O2 (35% in water), 1 mL
EtOH, r.t., 16 h.
mercially available. Unfortunately, most amino acids showed no
activity without any conversion of the substrate, assuming none to
low activity of the ␣-amino function. Fig. 1 is displaying the amino
acids, which showed at least low activities yielding the desired
compound 3. Cysteine, tryptophan, glycine and methionine fur-
nished 3–11% of the product, if 10 mol% of the catalyst were applied.
Nevertheless, all four amino acids have poor activities being not
Scheme 2. Epoxidation of 2-ethylhex-2-enal (2) into the corresponding epoxy
aldehyde 3.
attractive in further studies regarding the epoxidation.
In contrast to other amino acids, the basic amino acids, lysine
tions regarding the amino acid catalysed homo aldol condensation
[10] towards the development of the desired tandem aldol conden-
sation/epoxidation. Butanal (1) was chosen as model substrate in
the tandem catalysis synthesizing the desired product 3 without
isolating the intermediate 2, for being by far the most important
aldehyde, which is produced via the hydroformylation process. 12
million tons hydroformylation products were produced in 2009
with a share of 73% for 1 [11].
and arginine, showed higher activities in the epoxidation, which are
displayed in Fig. 2. Moderate yields were observed, if arginine and
lysine were used as catalysts in the epoxidation of 2-ethylhex-2-
enal (2), with a maximum of 43%. The activity of the reaction system
is not increasing by catalyst concentrations above 6.67 mol%. Both
amino acids are characterised by basic side chains with a guani-
dine and a primary amine group. Possible reasons for the activity
of arginine and lysine in the epoxidation will be discussed later on.
A summary of the achieved results with catalytic amounts of the
20 proteinogenic amino acids as organocatalysts in the epoxidation
of 2-ethylhex-2-enal (2) is given in Fig. 3.
3.1. Epoxidation with proteinogenic amino acids
Since arginine and lysine as catalysts led to moderate yields
in the epoxidation, further investigations were made regarding
the diastereoselectivity (Fig. 5) and enantoselectivity (Fig. 6). The
In the first part of our investigations every single proteinogenic
amino acid was applied in catalytic amounts in the epoxidation
step. We used them as drawn, since their L-form is easily com-

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K.A. Ostrowski et al. / Applied Catalysis A: General 509 (2016) 1–7
Fig. 4. Observed major and minor diastereomers.
major and minor diastereomers are displayed in Fig. 4 and were
determined by comparing our results with the results observed in
literature [7e] (please see our supporting information for further
details).
By plotting the diastereomeric ratio (major diastereomers
3a:minor diastereomers 3b = d.r.) against the catalyst concentra-
tion, an increasing of the d.r. was observable. This ratio increased
almost linearly with the catalyst concentrations.
Fig. 6. Conditions: 3 mmol 2, amino acid, 1.1 eq H2O2 (35% in water), 1 mL EtOH,
r.t., 16 h.
Unfortunately, the plot of the ee against the catalyst concentra-
tion revealed, that the major diastereomer 3a of the arginine and
lysine catalysed epoxidation has almost no enantiomeric excess
(ee). The ee of 3a was varying between 0% to 7% ee, while the
minor diastereomer 3b had a higher ee of 42% or 26%, if low catalyst
concentrations of 1.67% arginine or lysine were used. In this inves-
tigation a strong dependency between the enantiomeric excess and
the catalyst concentration could be observed. The ee is decreasing
almost linearly by increasing the catalyst concentration until an
inversion of the enantiomeric excess occurred. Therefore, at higher
catalyst concentrations than 10 mol% lysine or 20 mol% arginine an
inversion of the enantiomeric excess could be obtained with −14%
or −11% ee, while the yields remained at the same level. Inversion
of enantioselectivities, which depend on catalyst loadings, has been
already observed in the cinchona-mediated desymmetrization [12]
and in the alkaloid-mediated thiolyses [13].
3.2. Optimisation of the epoxidation
We set our focus on optimising the yield, since high yields and
selectivities are important for future developments and applica-
tions. Higher equivalents of the oxidising agent hydrogen peroxide
were added to increase the yield of the epoxy aldehyde 3 (Fig. 7).
Higher yields were obtained significantly, if more hydrogen perox-
ide was added and almost quantitative yields of 97% were observed
at 4 equivalents H2O2. Based on these results, we investigated
the reaction progress (Fig. 8). For an almost full conversion of 2-
ethylhex-2-enal (2) a reaction time of 16 h is needed while a very
Fig. 5. Conditions: 3 mmol 2, amino acid, 1.1 eq H2O2 (35% in water), 1 mL EtOH,
Fig. 7. Conditions: 3 mmol 2, amino acid, H2O2 (35% in water), 1 mL EtOH, r.t., 16 h.
r.t., 16 h.

K.A. Ostrowski et al. / Applied Catalysis A: General 509 (2016) 1–7
5
Scheme 3. Lysine catalysed one pot aldol condensation/epoxidation.
Table 1
Establishing a new tandem aldol condensation/epoxidation.
No.
Substrate
[mmol]
H2O2 [eq]
AS
X1
ꢀY(2+3)
Y2
Y3
d.r.(3)
1.1a
1.2a
1.3a
1.4
3
3
6
3
3
3
6
2
5
2
2
5
2
2
Lys
Lys
Lys
Arg
Arg
Arg
Arg
74
79
92
88
87
>99
94
60
61
74
84
81
86
91
26
30
11
10
9
34
31
63
74
72
84
87
2.3
2.3
2.1
2.1
1.9
1.9
1.9
1.5
1.6b
1.7
2
4
Conditions: 1st step = 1 as substrate, 3.33 mol% lysin or 6.67 mol% arginin, 1 mL EtOH,
r.t., 3 h; 2nd step = adding H2O2 (35% in water), r.t., 16 h; all results in %.
a
Additionally, 3.33 mol% lysin was added in the 2nd step.
16 h for 1st step & 24 h for 2nd step.
b
A combination of both optimised reaction conditions (of the
aldol condensation and epoxidation) led to a successful develop-
ment of an one-pot catalysis (Entry 1.1, Table 1). 34% of the epoxy
aldehyde 3 was obtained directly from 1 besides 26% not converted
aldol condensate 2-ethylhex-2-enal (2) as intermediate. Additional
amounts of H2O2 (Entry 1.2) were not converting the remaining
aldol intermediate obtaining similar results as in Entry 1.1.
Increasing the theoretically maximum yield of the intermedi-
ate to 3 mmol/mL by employing 6 mmol/mL butanal (1) should
enhance the yield of 3. Therefore, the yield of the desired prod-
uct increased to 63% with only 11% remaining intermediate (Entry
1.3). Nevertheless, higher conversions of the intermediate 2 were
expected, since investigations regarding the epoxidation showed
quantitative yields for the product (Fig. 7). Probably, lysine was not
stable during longer reaction times and underwent side reactions.
These side reactions would explain the gap between the conversion
of the aldehyde and obtained yield of the intermediate and the final
product.
The employment of arginine as organocatalyst in both reactions,
aldol condensation and epoxidation, should enable the develop-
ment of an assisted tandem catalysis [1b] (Scheme 4). Advantages
of the displayed assisted tandem catalyses over the displayed one
pot catalysis (Scheme 3) are a more simple reaction system with
less additional reagents, an easier reaction control and handling.
6.67 mol% arginine catalyse both reaction steps in an assisted
tandem catalyses successfully leading to a good yield for the epoxy
aldehyde 3 of 74% with high conversions of the intermediate (Entry
1.4). More equivalents of H2O2 were not converting the remaining
intermediate into the desired product (Entry 1.5). By using longer
reaction times, a very good yield of 84% for the product 3 was
Fig. 8. Conditions: 3 mmol 2, amino acid, 4 eq H2O2 (35% in water), 1 mL EtOH, r.t.,
16 h.
good yield of 92–94% could be achieved already after 8 h. In the
next step, we combined the epoxidation reaction with an aldol
condensation in order to form product 3 directly from butanal (1).
3.3. Development of a tandem catalysis
Investigations regarding the aldol condensation [10] empha-
sised a strong dependency of the catalyst concentration versus
yield. Arginine and lysine led to high yields at low catalyst con-
centrations of 6.67 mol% (arginine) respectively 3.33 mol% (lysine).
Therefore, more lysine needs to be added additionally in the epoxi-
dation step, securing a higher catalyst concentration for the second
step (Scheme 3). According to the nomenclature in the litera-
ture [1b] this reaction sequence is called one-pot catalyses, since
additional catalyst was added for the epoxidation step. First exper-
iments showed that it is important to induce the epoxidation with
the addition of H2O2 after the aldol condensation, since no conver-
sion of the substrate butanal (1) was observed, if H2O2 was added
from the beginning.
Scheme 4. Arginine catalysed assisted tandem aldol condensation/epoxidation.

6
K.A. Ostrowski et al. / Applied Catalysis A: General 509 (2016) 1–7
Fig. 9. Side chains of lysine and arginine.
Scheme 5. Developed arginine catalysed assisted tandem catalysis; Conditions: 1st
step = 6 mmol, 6.67 mol% arginin, 1 mL EtOH, RT, 3 h; 2nd step = 2 eq H2O2 (35% in
water), 16 h.
Table 2
Other substrates in the new tandem aldol condensation/epoxidation.
No.
Substrate
H2O2[eq]
Yaldolcondensate
Yepoxyaldehyde
ꢀY
2.1
2.2
2.3
2.4
2
4
2
4
34
16
29
16
23
42
49
42
57
58
78
58
Scheme 6. n-Butyl amine and guanidine as not-efficient organocatalysts in the
homo aldol condensation [10].
Table 3
Conditions: 1st step = 6 mmol substrate, 6.67 mol% arginin, 1 mL EtOH, r.t., 3 h; 2nd
step = adding H2O2 (35% in water), r.t., 16 h; all results in %.
Detailed studies regarding the catalytic activity of the side chain groups of the basic
amino acids.
No.
Catalyst
[mol%]
6.67
Y3
d.r. (3)
observed (Entry 1.6). This was improved even more, since the appli-
cation of higher substrate concentrations at shorter reaction times
(3 h + 16 h) led to increased yields of 87% for the desired product
3 with only 4% remaining intermediate (Entry 1.7). In summary,
90% yield for the intermediate aldol condensate was obtained, from
which 97% was converted into the desired compound 3 leading
to an overall yield of 87% within the assisted tandem catalyses
(Scheme 5).
3.1
3.2
3.3
3.4
3.5
Lysine
Arginine
nBuNH2
43
43
41
55
52
2.0
2.0
1.9
1.0
1.1
6.67
6.67
6.67
3.33
Guanidine × 1/2 CO3H2
Na2CO3
Conditions: 3 mmol 2, amino acid, 110 mol% H2O2 (35% in water), 1 mL EtOH, r.t.,
16 h; all results in %.
Other substrates, propanal (5) (Entries 2.1–2.2) and phenyl-
propionaldehyde (6) (Entries 2.3–2.4), were applied successfully
at same conditions (Table 2). Unfortunately, lower yields were
achieved. The lower activity of 6 can be explained by a bipha-
sic reaction mixture leading to a phase transfer limitation. Higher
concentrations of hydrogen peroxide did not lead to higher yields
(Entries 2.2 and 2.4).
simulating an amino acid mixture almost no yield of the aldol con-
densate 2 have been observed [10].
Then, we applied n-butyl amine and guanidine in the epoxida-
tion of 2 (Table 3). Both moieties showed catalytic activity obtaining
similar yields of 41–55% (Entries 3.3–3.4), if compared to the lysine
(Entry 3.1) and arginine (Entry 3.2) catalysed epoxidation with
yields of 43%. The reaction mechanism of these catalysts can be
explained by an iminium catalysis [7e]. The commercially avail-
able guanidine carbonate salt showed higher activity leading to
55% yield of the epoxy aldehyde 3 assuming an enhanced catalytic
activity, due to the carbonate activation of hydrogen peroxide [14]
analogous to the bicarbonate activation [15] (Formula 1). Na2CO3
was catalytically active in the epoxidation as well (Entry 3.5).
3.4. Amino acids with different catalytic centres in their structure
In Fig. 3 the results of the proteinogenic amino acid catalysed
epoxidation were summarised. Most of these amino acids were not
active as organocatalyst in the epoxidation, if applied in catalytic
amounts (1.67–20 mol%). Only the basic amino acids, arginine and
lysine, catalysed the epoxidation successfully. Both amino acids are
characterised by a guanidine or a butyl amine side chain (Fig. 9),
which could be a further active catalyst centre for organo cat-
alytic reactions besides the ␣-amino function. Therefore, n-butyl
amine and guanidine salt were applied in the homo aldol condensa-
tion of butanal (1) and in the epoxidation of 2-ethylhex-2-enal (2).
Both compounds represent the side chains of lysine and arginine
(Scheme 6).
HCO−3 + H2O2 ꢀ HCO− + H2O
4
Formula 1. Equilibrium of bicarbonate and hydrogen peroxide.
On the basis of these investigations, we can divide the molecu-
lar structure of lysine and arginine in two catalytic centres, which
catalyses different reactions in the tandem catalysis (Fig. 10). The
␣-amino group is catalytically active in the homo aldol conden-
sation of aldehydes, which is described by enamine catalysis [10].
This ␣-amino group is not active as catalyst in the epoxidation,
explaining the poor to non-conversion of 2 if using the other 18
proteinogenic amino acids, which are displayed in Fig. 3. The side
chains, butyl amine and guanidine, are active in the epoxidation
n-Butyl amine and guanidine were not active in the homo
aldol condensation of 1 at given conditions, proving that only the
␣-amino function of lysine and arginine is active in the enam-
ine catalysis/homo aldol condensation. Even if acid was added
Fig. 10. Displayed different catalytic centres of lysine and arginine.

K.A. Ostrowski et al. / Applied Catalysis A: General 509 (2016) 1–7
[2] P.T. Anastas, J.C. Warner, Green Chemistry—Theory and Practice, Oxford
7
of ␣-branched ␣,␤-unsaturated aldehydes, which explains the low
enantioselectivities.
University Press, Oxford, 1998.
[3] (a) P. Eilbracht, L. Bärfacker, C. Buss, C. Hollmann, B.E. Kitsos-Rzychon, C.L.
Kranemann, T. Rische, R. Roggenbuck, A. Schmidt, Chem. Rev. 99 (1999)
3329–3366;
4. Conclusion
(b) J. Stiller, A.J. Vorholt, K.A. Ostrowski, A. Behr, M. Christmann, Chem. Eur. J.
18 (2012) 9496–9499;
In summary, we investigated 20 proteinogenic amino acids
in the epoxidation of an ␣-branched ␣,␤-unsaturated aldehyde,
wherein most of them were not catalytically active. The application
of the basic amino acids, lysine and arginine, as organocata-
lysts in the epoxidation led to excellent yields with 97% of the
epoxy aldehyde 3. A practically simple tandem aldol condensa-
tion/epoxidation was successfully developed using arginine as the
only catalyst, whereby a very good yield of 87% the desired com-
pound 3 could be obtained directly from butanal (1). Detailed
studies revealed that lysine and arginine have two different
catalytic centres. The ␣-amino function catalyses the aldol conden-
sation and the side group, which contains a butyl amine (lysine) or
a guanidine (arginine) group, catalyses the epoxidation. In future,
these studies can help in further catalyst designs, which are char-
acterised by the synergy of different catalytic centres catalysing
different reactions. Furthermore, the used substrate 1 is produced
on industrial scale, therefore the developed tandem catalysis is
showing an attractive perspective for useful and reactive products,
which are based on substrates with high interest.
(c) X. Fang, R. Jackstell, R. Franke, M. Beller, Chem. Eur. J. 20 (2014)
13210–13216;
(d) X. Fang, R. Jackstell, A. Börner, M. Beller, Chem. Eur. J. 20 (2014)
15692–15696;
(e) K.A. Ostrowski, T.A. Faßbach, A.J. Vorholt, Adv. Synth. Catal. 357 (2015)
1374–1380;
(f) K.A. Ostrowski, T.A. Faßbach, D. Vogelsang, A.J. Vorholt, Chem. Cat. Chem. 7
(2015) 2607–2613.
[4] (a) F.G. Fischer, A. Marschall, Ber. Dtsch. Chem. Ges. 64 (1931) 2825–2827;
(b) W. Notz, C.F.B. Iii, N. Torrey, P. Road, J. Org. Chem. 67 (2002) 301–303;
(c) B. Nozière, P. Dziedzic, A. Córdova, Geophys. Res. Lett. 34 (2007);
(d) B. Nozière, A. Córdova, J. Phys. Chem. A 112 (2008) 2827–2837;
(e) Y. Watanabe, K. Sawada, M. Hayashi, Green Chem. 12 (2010) 384–386.
[5] I. Kumar, P. Ramaraju, N.A. Mir, Org. Biomol. Chem. 11 (2013) 709–716.
[6] M. Marigo, J. Franzén, T.B. Poulsen, W. Zhuang, K.A. Jørgensen, J. Am. Chem.
Soc. 127 (2005) 6964–6965.
[7] (a) S. Lee, D.W.C. MacMillan, Tetrahedron 62 (2006) 11413–11424;
(b) H. Sundén, I. Ibrahem, A. Córdova, Tetrahedron Lett. 47 (2006) 99–103;
(c) G.L. Zhao, I. Ibrahem, H. Sundén, A. Córdova, Adv. Synth. Catal. 349 (2007)
1210–1224;
(d) O.A. Wong, Y. Shi, Chem. Rev. 108 (2008) 3958–3987;
(e) O. Lifchits, M. Mahlau, C.M. Reisinger, A. Lee, C. Farès, I. Polyak, G.
Gopakumar, W. Thiel, B. List, J. Am. Chem. Soc. 135 (2013) 6677–6693;
(f) R.L. Davis, K.L. Jensen, B. Gschwend, K.A. Jørgensen, Chem. Eur. J. 20 (2014)
64–67.
[8] (a) S. Zakavi, A. Abasi, A.R. Pourali, S. Rayati, Bull. Korean Chem. Soc. 29 (2008)
866–868;
(b) O. Lifchits, C.M. Reisinger, B. List, J. Am. Chem. Soc. 132 (2010)
10227–10229.
[9] (a) G.B. Payne, J. Org. Chem. 26 (1961) 205;
Acknowledgments
We thank CS-Chromatographie Service GmbH for providing us
their gc column EnantioSELECT® for a successful separation of the
epoxy aldehyde isomers 3a and 3b. Furthermore, we thank J. Stiller
for his motivation and inspiration regarding the development of a
tandem catalysis including an epoxidation step.
(b) W. Zhang, S.R. Wilson, E.N. Jacobsen, J. Am. Chem. Soc. 112 (1990)
2801–2803.
[10] K.A. Ostrowski, D. Lichte, M. Stuck, A.J. Vorholt, submitted.
[11] (a) H. Bahrmann, H.-D. Hahn, D. Mayer, G.D. Frey, Ullmann’s Encyclopedia of
Industrial Chemistry, Wiley–VCH Verlag GmbH & Co. KGaA, Weinheim, 2013;
(b) H. Bahrmann, H. Bach, G.D. Frey, Ullmann’s Encyclopedia of industrial
Chemistry, Wiley–VCH Verlag GmbH & Co. KGaA, Weinheim, 2013;
(c) D.K. Raff, Ullmann’s Encyclopedia of industrial Chemistry, Wiley–VCH
Verlag GmbH & Co. KGaA, Weinheim, 2013.
Appendix A. Supplementary data
[12] (a) T. Ivsˇic´, Z. Hamersˇak, Tetrahedron Asymm. 20 (2009) 1095–1098;
(b) T. Ivsˇic´, J. Novak, N. Dosˇlic´, Z. Hamersˇak, Tetrahedron 68 (2012)
8311–8317.
[13] E. Schmitt, I. Schiffers, C. Bolm, Tetrahedron 66 (2010) 6349–6357.
[14] W.C. Frank, Tetrahedron Asymm. 9 (1998) 3745–3749.
[15] D.E. Richardson, H. Yao, K.M. Frank, D.A. Bennett, J. Am. Chem. Soc. 122 (2000)
1729–1739.
Supplementary data associated with this article can be found,
in the online version, at http://dx.doi.org/10.1016/j.apcata.2015.10.
018.
References
[1] (a) L.F. Tietze, Chem. Rev. 96 (1996) 115–136;
(b) D.E. Fogg, E.N. dos Santos, Coord. Chem. Rev. 248 (2004) 2365–2379;
(c) H. Pellissier, Tetrahedron 69 (2013) 7171–7210;
(d) A. Behr, A.J. Vorholt, K.A. Ostrowski, T. Seidensticker, Green Chem. 16
(2014) 982–1006.