Enantioselective Reduction of Ethyl 3-Oxo-5-phenylpentanoate with Whole-Cell Biocatalysts

Article abstract of DOI:10.1002/ejoc.201501460

The biocatalytic stereoselective synthesis of a sterically demanding sec-alcohol (ethyl 3-hydroxy-5-phenylpentanoate) was investigated by starting from the corresponding prochiral ketone. Screening of a collection of microorganisms led to the identificati

Full text of DOI:10.1002/ejoc.201501460

DOI: 10.1002/ejoc.201501460
Full Paper
Enantioselective Reduction
Enantioselective Reduction of Ethyl 3-Oxo-5-phenylpentanoate
with Whole-Cell Biocatalysts
Anna Zadlo,[a] Joerg H. Schrittwieser,[b] Dominik Koszelewski,[a] Wolfgang Kroutil,*[b] and
Ryszard Ostaszewski*[a]
Abstract: The biocatalytic stereoselective synthesis of a steri- tors, recycling systems and 2-propanol amounts were optimized
cally demanding sec-alcohol (ethyl 3-hydroxy-5-phenylpentano-
ate) was investigated by starting from the corresponding pro-
chiral ketone. Screening of a collection of microorganisms led
to the identification of stereocomplementary catalysts suitable
for accessing both enantiomers of the target compound. Cofac-
for selected biocatalysts, leading to excellent enantiomeric ex-
cesses for the obtained hydroxy ester with up to 99 % ee. The
utility of the identified strains was showcased by using prepara-
tive-scale reactions.
Introduction
nity to fulfill the principles of green chemistry.[13] Such alterna-
tive methods enable reduced use of organic solvents, dimin-
ished production and/or use of toxic metals and diminished
environmental footprints.[14]
Enantiomerically pure ꢀ-hydroxy esters[1] have been used as
building blocks for the synthesis of a variety of chemicals, in-
cluding ꢀ-lactams,[2] carotenoids,[3] insect pheromones[4] and
2,3-dihydro-4H-pyran-4-ones.[5] To date, only a few reports have
described the asymmetric synthesis of 3-hydroxy-5-phenyl-
pentanoic acid derivatives.[6–8] Most of the reported synthetic
routes are based on stereoselective reductions by using baker's
yeast. Athanasiou and co-workers have reported the use of an
organic solvent system for yeast-mediated reductions of a series
of ꢀ-oxo esters.[9] Some serious drawbacks are associated with
this biocatalyst; for instance, low productivity, large amounts
of biomass and generation of many side products are often
characteristic of yeast-based reductions.[10,11] A few years later,
Padhi et al. published the deracemization of aryl-substituted ꢀ-
hydroxy esters by using immobilized whole cells from Candida
parapsilosis ATCC 7330; the corresponding (S) enantiomers of
these compounds were generated with moderate enantiomeric
excesses (87 %) and low yields (10 %).[12] Unfortunately, the re-
ported procedures provided only the (S) enantiomer. In this
work, we focus our attention on new biocatalysts, which may
provide access to both enantiomers of ethyl 3-hydroxy-5-
phenylpentanoate in optically pure form. To achieve this goal,
a series of whole-cell biocatalysts was screened. These efforts
are inspired, in large part, by the realization that the application
of biocatalysis to create complex molecules offers the opportu-
Results and Discussion
In the present study, we report the biocatalytic synthesis of
both enantiomers of ethyl 3-hydroxy-5-phenylpentanoate (1).
The corresponding ketone substrate 2 was obtained in a two-
step synthesis (Scheme 1). C–C bond formation between 3-
phenylpropionaldehyde and ethyl acetate afforded racemic al-
cohol rac-1, which was oxidized with Jones reagent (CrO3,
H2SO4, acetone) to produce ꢀ-oxo ester 2.[15,16]
Scheme 1. Synthesis of ethyl 3-oxo-5-phenylpentanoate (2).
In a first approach two recombinant alcohol dehydrogenases
(ADHs), heterologously expressed in E. coli, were assessed for
the ability to catalyze the asymmetric reduction of compound
2 (Scheme 2). Since ADH-catalyzed reactions rely on cofactors,
an effective method for cofactor regeneration was required.
Many whole-cell biocatalysts have internalized cofactor-regen-
eration mechanisms that can be enabled upon the addition of
co-substrates such as glucose.[17] To have comparable condi-
tions for a broader screening of wild-type microorganisms, gluc-
ose/glucose dehydrogenase (GDH) as well as 2-propanol were
[a] Institute of Organic Chemistry Polish Academy of Sciences
Kasprzaka 44/52, 01-224 Warsaw, Poland
E-mail: ryszard.ostaszewski@icho.edu.pl
http://ww2.icho.edu.pl/z20/
[b] Department of Organic Chemistry, Organic and Bioorganic Chemistry,
University of Graz
Heinrichstrasse 28, 8010 Graz, Austria
http://biocatalysis.uni-graz.at
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/ejoc.201501460.
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used in the screening reactions, whereby the latter may serve the basis of HPLC) and in a low enantiomeric excess (49 %). Due
not only as the hydride donor but also as co-solvent to improve to the low enantiomeric excess obtained, further experiments
substrate solubility.[18] To have both nicotinamide cofactors aimed at preparing enantiomerically pure hydroxy ester 1 were
(NADH, NADPH) present in sufficient quantities, a mixture of the performed. Consequently, a collection of wild-type whole-cell
two was added. Some ADHs display high cofactor specificity, biocatalysts was screened for their reactivity with 2.
whereas others are able to accept both cofactors equally
well.[19]
Table 1. Reduction of oxo ester 2 with recombinant ADHs.[a]
Entry
ADH
c [%]
Yield [%]
ee [%]
1
2
Ralstonia sp. DSM 6428
Sphingobium yanoikuyae DSM 6900
> 99
n.d.
54
<1
49 (S)
n.d.[b]
[a] Conditions: 10 mg of freeze-dried E. coli cells containing the recombinant
ADH, glucose dehydrogenase (1 mg mL–1), 20 m
glucose, 0.5 m NADH,
0.5 m NADPH, 10 m substrate in 500 μL reaction mixture Tris-HCl buffer
M
M
M
M
pH 7.5/2-propanol (90:10, v/v), 30 °C, 120 rpm in a thermoshaker for 20 h.
Conversion (i.e., consumption of substrate) and product yield (i.e., formation
of 1) were determined by HPLC analysis on an achiral stationary phase by
using calibration curves for 1 and 2. The ee of 1 was determined by HPLC
analysis on a chiral stationary phase. [b] n.d. = not determined.
Scheme 2. Whole-cell-mediated reduction of ethyl 3-oxo-5-phenylpentano-
ate.
In comparing the results collected for the two recombinant
ADHs it is clear that the ADH from Sphingobium yanoikuyae[20,21]
About 250 microorganisms from the in-house culture collec-
did not accept ꢀ-oxo ester 2 as a substrate (Table 1, Entry 2). tion, encompassing mainly commercially available strains,[24,25]
Conversely, the ADH from Ralstonia sp.[22,23] (Table 1, Entry 1) have been assessed for their ability to reduce ꢀ-oxo ester 2;
afforded the desired (S) product with moderate yield (54 % on only 33 of these were found to be active (see Table 2).
Table 2. Reduction of oxo ester 2 with whole-cell biocatalysts.[a]
Entry
Microorganism
Strain
c [%]
Yield [%]
ee [%]
1
2
3
4
5
6
7
8
Alcaligenes sp.
Arthrobacter sp.
DSM 2625
DSM 7325
FCC018
FCC019
FCC027
FCC022
FCC023
FCC026
FCC025
68
> 99
> 99
> 99
94
98
95
> 99
90
94
36
82
49
46
24
11
14
12
19
28
29
32
65
14
34
70
62
55
51
70
47
79
33
44
16
21
10
26
10
23
7
5 (S)
85 (R)
77 (S)
77 (S)
96 (R)
90 (R)
92 (R)
88 (R)
89 (R)
70 (R)
45 (R)
27 (S)
43 (R)
23 (S)
61 (S)
48 (R)
49 (R)
47 (R)
64 (S)
88 (R)
92 (S)
77 (R)
49 (S)
66 (S)
98 (R)
94 (R)
96 (R)
67 (R)
90 (R)
78 (R)
98 (R)
60 (R)
62 (R)
isolate Gordonia sp. NAM-BN063A
isolate Gordonia sp. NAM-BN063B
isolate Actinomyces sp. SRB-AN053
isolate Actinomyces sp. SRB-AN019
isolate Actinomyces sp. SRB-AN029
isolate Actinomyces sp. SRB-AN042
isolate Actinomyces sp. SRB-AN040
isolate Actinomyces sp. SRB-AN030
Coprinus radians
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
FCC024
CSM 888
DSM 1455
DSM 17552
DSM 17887
DSM 3434
DSM 50853
DSM 1050
DSM 1049
DSM 44369
DSM 4864
DSM 11072
CBS 7435
DSM 6978
DSM 14292
FCC014
FCC015
FCC021
FCC013
FCC028
FCC020
FCC139
FCC183
FCC042
72
85
98
93
Comamonas testosteroni
Comamonas badia
Comamonas denitrificans
Kluyveromyces thermotolerans
Xanthomonas arboricola pvar. Celebensis
Xanthomonas campestris
Xanthomonas sp.
95
> 99
> 99
> 99
96
> 99
60
> 99
72
98
94
94
99
91
Gordonia alkanivorans
Lactobacillus oris
Paracoccus pantotrophus
Pichia pastoris
Pseudomonas sp.
Pseudomonas thermotolerans
isolate ARG-AN024
isolate ARG-AN025
isolate USA-AN012
isolate ANTs-AN002
isolate Actinomyces sp. 67-BEN001
isolate Actinomyces sp. ENG-AN033
Sphingomonas sp. HXN200
Sphingomonas faenia
96
95
98
76
51
8
bacterium (code 0091B)
97
[a] Conditions: 10 mg of lyophilized biocatalyst, glucose dehydrogenase (1 mg mL–1), 20 m
M
glucose, 0.5 m
M
NADH, 0.5 m
M
NADPH, 10 m
M
substrate in
500 μL reaction mixture Tris-HCl buffer pH 7.5/2-propanol (90:10, v/v), 30 °C, 120 rpm in a thermoshaker for 20 h. Conversion (i.e., consumption of substrate)
and product yield (i.e., formation of 1) were determined by HPLC analysis on an achiral stationary phase by using calibration curves for 1 and 2. The ee of 1
was determined by HPLC analysis on a chiral stationary phase.
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Table 3. Optimization of the reaction conditions.[a]
Entry
Microorganism
NADH [m
M]
NADPH [m
M]
Glucose [m
M]
2-PrOH [%]
c [%]
Yield [%]
ee [%]
1
2
3
4
5
6
7
8
9
isolate Actinomyces sp. SRB-AN053
isolate Actinomyces sp. SRB-AN053
isolate Actinomyces sp. SRB-AN053
isolate Actinomyces sp. SRB-AN053
isolate Actinomyces sp. SRB-AN053
isolate Actinomyces sp. SRB-AN053
Arthrobacter sp.
0.5
0.5
0.5
–
0.5
0.5
0.5
–
0.5
0.5
0.5
0.5
–
0.5
0.5
0.5
–
20
20
20
20
20
–
20
20
20
–
10
20
30
10
10
10
10
10
10
10
94
92
24
99
96
95
> 99
56
99
98
24
23
9
16
24
26
82
18
59
45
96 (R)
98 (R)
n.d.[b]
97 (R)
95 (R)
> 99 (R)
85 (R)
11 (R)
96 (R)
96 (R)
Arthrobacter sp.
Arthrobacter sp.
Arthrobacter sp.
0.5
0.5
10
0.5
[a] Conditions: 10 mg of lyophilized biocatalysts, glucose dehydrogenase (1 mg mL–1), 20 m
M glucose, 0.5 mM NADH, 0.5 mM NADPH, 10 mM substrate in
500 μL reaction mixture Tris-HCl buffer pH 7.5/2-propanol (90:10; v/v), 30 °C, 120 rpm in a thermoshaker for 20 h. Conversion (i.e., consumption of substrate)
and product yield (i.e., formation of 1) were determined by HPLC analysis on an achiral stationary phase using calibration curves for 1 and 2. The ee of 1 was
determined by HPLC analysis on a chiral stationary phase. [b] n.d. = not determined.
Table 4. Reduction of 2 with whole-cell biocatalysts on a 1 mmol scale.
Entry
Microorganism
Substrate recovery [%]
Yield [%][a]
ee [%]
1
2
3
Arthrobacter sp.[b]
6
5
40
47
23
41
94 (R)
> 99 (R)
92 (S)
isolate Actinomyces sp. SRB-AN053[c]
Paracoccus pantotrophus[d]
[a] Yield refers to isolated product 1 after column chromatography. [b] Conditions: 30 °C, 120 rpm in a thermoshaker for 48 h, 2 g of whole-cell lyophilized
biocatalyst in 100 mL of reaction solution, containing 20 m glucose, 0.5 m NADH, 1 mmol substrate in mixture of 100 m Tris-HCl buffer pH 7.5/2-propanol
(90:10, v/v). [c] Glucose dehydrogenase (1 mg mL–1). [d] 0.5 m NADPH, glucose dehydrogenase (1 mg mL–1).
M
M
M
M
Out of the tested biocatalysts, isolate Gordonia sp. NAM- absence of glucose and GDH. In contrast, the ability of Arthro-
BN063A (Table 2, Entry 3) and Paracoccus pantotrophus (Table 2, bacter sp. to catalyze reactions with high ee was NADH-depend-
Entry 21) afforded (S)-configured product 1 with enantiomeric ent (Table 3, Entry 9). We reason that this microorganism may
excesses of 77 and 92 %, respectively. Moreover, the use of Ar- contain a second, less selective dehydrogenase, which is
throbacter sp. (Table 2, Entry 2), isolate Actinomyces sp. SRB- NADPH-dependent (Table 3, Entry 8). Interestingly, combining
AN053 (Table 2, Entry 5), isolate ARG-AN024 or Sphingomonas both NADH and NADPH resulted in the activation of both en-
sp. HXN200 provided the opposite (R) enantiomer with excel- zymes leading to higher yields but with lower enantiomeric
lent enantiomeric excesses of up to 98 %. Due to the presence excesses (Table 3, Entry 7). A conversion of 59 % with an ee of
of various types of enzymes in whole-cell catalysts, various side 96 % was achieved after 24 h in buffer-containing additional
reactions often occur. Substrate 2, containing more than one NADH and glucose for internal cofactor regeneration. Reaction
reactive group, was found to be amenable to high conversions supplementation with glucose improved the reaction efficiency
(> 60 %), but moderate yields of the desired products (11– but appeared to have no impact upon the ee (Table 3, Entry 9
82 %). Thus, yields above 70 % of product 1, were observed vs. 10).
only in a few cases (Table 2, Entries 2, 16, 20, 22).
Finally, to highlight the utility of the developed procedure,
Although the achieved stereoselectivities were often excel- experiments were run on a large scale (1 mmol; Table 4). Thus,
lent, the chemoselectivities of whole-cell bioreductions with re- 220 mg of ꢀ-oxo ester 2 was transformed into ꢀ-hydroxy ester
spect to carbonyl bond reduction vs. ester bond hydrolysis were 1; the reaction at 30 °C was complete within 24 h. The yields
found to be moderate. Driven by this observation, cofactors, of isolated products on a preparative scale were similar to those
recycling systems and the amounts of 2-propanol employed in determined in analytical-scale experiments. Both enantiomers
reactions were consequently optimized for selected biocata- of compound 1 were obtained with good yields and in excel-
lysts.
lent enantiomeric excesses of up to 99 %. This finding repre-
sents a significant step forward, since suitable enantioselective
biocatalysts have not been described for this substrate. The ab-
solute configuration of products was assigned on the basis of
optical-rotation measurements.[12,26]
To slow down the hydrolysis reaction, larger quantities of
2-propanol were investigated. An increase of the 2-propanol
concentration from 10 to 20 % did not affect the product yield
(Table 3, Entry 2). A larger increase in the 2-proponal concentra-
tion diminished the efficiency of both hydrolysis and reduction
reactions (Table 3, Entry 3). Whole cells of Actinomyces sp. SRB-
AN053 were used for the reduction of oxo ester 2 to the corre-
sponding (R)-hydroxy ester with excellent stereoselectivity of
Conclusions
> 99 % (Table 3, Entry 6). Independent of the cofactor added, Screening of various enzymes and microorganisms led to the
high ee values were obtained (Table 3, Entries 4 and 5). Notably, identification of suitable wild-type whole-cell catalysts for the
the conversions achieved were independent of the presence or reduction of the sterically demanding ketone 2. Following reac-
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quenched by the addition of saturated ammonium chloride solu-
tion and the mixture left to warm to room temperature. The two
layers were separated, and the aqueous layer was extracted with
ethyl acetate (3 × 100 mL). The combined organic layers were dried
with MgSO4, filtered, and concentrated in vacuo. The crude product
was purified by column chromatography on silica gel by using hex-
ane/ethyl acetate (8:2, v/v). The product was obtained as a colorless
oil (16.7 mmol, 3.7 g, 45 %). 1H NMR (CDCl3, 400 MHz): δ = 7.30–
7.26 (m, 2 H, Ar), 7.21–7.16 (m, 3 H, Ar), 4.19–4.14 (q, J = 7.1 Hz, 2
H, OCH2CH3), 4.04–3.99 (td, J1 = 8.3, J2 = 4.2 Hz, 1 H, CHOH), 3.06
(br. s, 1 H, OH), 2.82–2.80 (m, 1 H, CH2), 2.72–2.66 (m, 1 H, CH2),
2.52–2.40 (m, 2 H, CH2), 1.91–1.78 (m, 1 H, CH2), 1.78–1.64 (m, 1 H,
CH2), 1.28–1.25 (t, J = 7.2 Hz, 3 H, OCH2CH3) ppm. 13C NMR (CDCl3,
100 MHz): δ = 172.9, 141.7, 128.4, 128.4, 125.9, 67.2, 60.7, 41.3, 38.1,
31.7, 14.1 ppm. C13H18O3 (222.3): calcd. C 70.24, H 8.16; found C
70.11, H 8.33. HPLC (C-18 Luna): tr = 21.5 min. HPLC (OD-H Chiralcel):
tr1 = 7.1 min, tr2 = 8.1 min.
tion optimization, both enantiomers of ethyl 3-hydroxy-5-
phenylpentanoate were obtained with excellent optical purities
and high yields. The utility of the identified catalysts was show-
cased by carrying out the reaction on a preparative scale.
Experimental Section
General Remarks: 1H and 13C NMR spectra were recorded in CDCl3
solution with a Varian Gemini 400 MHz spectrometer. Chemical
shifts are expressed in parts per million (ppm) by using TMS as
an internal standard. Recombinant dehydrogenases and whole-cell
biocatalysts are from the collection of the Institute of Chemistry –
Organic and Bioorganic Chemistry, University of Graz. All chemicals
were commercial products of analytical grade. TLC was performed
by using Kieselgel 60 F254 aluminium sheets (Merck). Optical-rota-
tion measurements were executed with a Jasco P-2000 polarimeter.
For the determination of product (1) yields and substrate (2) con-
versions, 1.2 mL samples dissolved in methanol were analyzed by
HPLC with a Shimadzu Prominence LC-20A series instrument cou-
pled to a UV/Vis detector. A LUNA C-18 column (Phenomenex,
250 mm × 4.6 mm × 5 μm) was used with the following conditions:
eluent water/acetonitrile; low-pressure gradient from 100 % of wa-
ter to 100 % of acetonitrile over 20 min, 100 % of acetonitrile for
5 min, back to 100 % water over 5 min, 100 % water for 2 min;
temperature 30 °C; flow 0.5 mL min–1; λ = 210 nm. For the determi-
nation of product (1) ee values, 1.2 mL samples dissolved in meth-
anol were analyzed by HPLC with a Shimadzu Prominence LC-20A
series instrument coupled with a UV/Vis detector. A Chiralcel OD-H
column (Daicel, 250 mm × 4.6 mm × 5 μm) was used with the fol-
lowing conditions: eluent heptane/2-propanol (90:10, v/v); tempera-
ture 30 °C; flow 1.0 mL min–1; λ = 210 nm.
Ethyl 3-Oxo-5-phenylpentanoate (2): Jones reagent was prepared
by the addition of concentrated H2SO4 (30 mL) to CrO3 (33.5 g)
followed by careful dilution with water to give 250 mL of total solu-
tion. Then Jones reagent (17 mL, 17 mmol) was added dropwise to
a stirred solution of ethyl 3-hydroxy-5-phenylpentanoate (16 mmol,
3.55 g) in acetone (70 mL) at 0 °C. The solution was left to warm to
room temperature and stirred for 3 h. After this time, methanol
(7 mL) was added to quench any excess of the Jones reagent. The
mixture was extracted with Et2O (70 mL), the organic layer was
washed with water (3 × 50 mL) and brine (50 mL) and dried with
MgSO4. The crude product was purified by column chromatography
on silica gel by using hexane/ethyl acetate (8:2, v/v). The product
was obtained as colorless oil (67 %, 10.7 mmol, 2.36 g). 1H NMR
(CDCl3, 400 MHz): δ = 7.30–7.26 (m, 2 H, Ar), 7.21–7.17 (m, 3 H, Ar),
4.20–4.15 (m, 2 H, OCH2CH3), 3.41 (s, 2 H, COCH2CO), 2.93–2.86 (m,
4 H, 2 CH2), 1.28–1.24 (t, J = 7.2 Hz, 3 H, OCH2CH3) ppm. 13C NMR
(CDCl3, 100 MHz): δ = 201.8, 167.1, 140.5, 128.5, 128.3, 126.2, 61.4,
49.4, 44.5, 29.4, 14.1 ppm. C13H16O3 (220.3): calcd. C 70.89, H 7.32;
found C 70.97, H 7.43. HPLC (C-18 Luna): tr = 22.8 min.
Screening Procedure: Whole-cell biocatalysts (10 mg) were sus-
pended in reaction solution (500 μL), containing glucose dehydro-
genase (1 mg mL–1), 20 m
M
glucose, 0.5 m
M
NADH, 0.5 m
M NADPH,
10 m
M
substrate in a mixture of 100 m
M Tris-HCl buffer pH 7.5/2-
propanol (90:10, v/v). Biotransformations were conducted at 30 °C
and 120 rpm in a thermoshaker for 20 h. After this time, the reaction
mixture was extracted with ethyl acetate, centrifuged, and the su-
pernatant was transferred to an HPLC vial. The solvent was evapo-
rated under an air flow, the residue was re-dissolved in HPLC-grade
MeOH, and the samples were analyzed by HPLC.
Acknowledgments
We gratefully acknowledge the financial support of the National
Science Center (project Harmonia, no. 2014/14/M/ST5/00030)
and COST Action (CM1303, Systems Biocatalysis).
Preparative-Scale Procedure: Whole-cell biocatalyst (2 g) was sus-
pended in reaction solution (100 mL), containing glucose dehydro-
Keywords: Biotransformations · Dehydrogenase ·
Bioreduction · Asymmetric synthesis · Hydroxy esters ·
Biocatalysis
genase (1 mg mL–1), 20 m
M
glucose, 0.5 m
M
NADH, 0.5 m
M NADPH,
1 mmol of substrate in a mixture of 100 m
M
Tris-HCl buffer pH 7.5/
2-propanol (90:10, v/v). Biotransformations were conducted at 30 °C
and 120 rpm in a thermoshaker for 48 h. After this time, the biocata-
lyst was removed by centrifugation, and the reaction mixture was
extracted with ethyl acetate. The organic phase was separated,
dried (MgSO4), concentrated under reduced pressure, and the prod-
uct was purified by column chromatography on silica gel with pe-
troleum ether/ethyl acetate as eluent.
[1] M. Zysk, A. Zadlo, A. Brodzka, C. Wisniewska, R. Ostaszewski, J. Mol. Catal.
B 2014, 102, 225–229.
[2] D. M. Tsachen, L. M. Fuentes, J. E. Lynch, W. L. Laswell, R. P. Volante, I.
Shinkai, Tetrahedron Lett. 1988, 29, 2779–2782.
[3] A. Kramer, H. Pfader, Helv. Chim. Acta 1982, 65, 293–301.
[4] K. Mori, Tetrahedron 1989, 45, 3233–3298.
[5] M. Reiter, S. Ropp, V. Gouverneur, Org. Lett. 2004, 6, 91–94.
[6] K. Toribatake, L. Zhou, A. Tsuruta, H. Nishiyama, Tetrahedron 2013, 69,
3551–3560.
[7] A. Kamal, T. Krishnaji, G. B. R. Khanna, Tetrahedron Lett. 2006, 47, 8657–
8660.
Ethyl 3-Hydroxy-5-phenylpentanoate (1): To a precooled solution
(0 °C) of diisopropylamine (9 mL, 63.4 mmol, 1.7 equiv.) in anhy-
drous THF (280 mL), was added nBuLi (2.7
M in heptane, 20.7 mL,
55.8 mmol) under argon. The resulting reaction mixture was stirred
at 0 °C for 30 min and then cooled to –78 °C. Ethyl acetate (5.4 mL,
55.8 mmol, 1.5 equiv.) in anhydrous THF was added dropwise, and
the mixture was stirred at –78 °C for 1 h. After this time, 3-phenyl-
propionaldehyde (5 mL, 37.2 mmol, 1 equiv.) in anhydrous THF
(10 mL) was added. After stirring at –78 °C for 3 h, the reaction was
[8] C. Wolfand, M. Moskowitz, J. Org. Chem. 2011, 76, 6372–6376.
[9] N. Athanasiou, A. J. Smallridge, M. A. Trewhella, J. Mol. Catal. B 2001, 11,
893–896.
[10] R. Csuk, B. I. Glaenzer, Chem. Rev. 1991, 91, 49–97.
Eur. J. Org. Chem. 2016, 1007–1011
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[11]
[12]
[13]
[14]
[20] I. Lavandera, A. Kern, V. Resch, B. Ferreira-Silva, A. Glieder, W. M. F. Fabian,
S. de Wildeman, W. Kroutil, Org. Lett. 2008, 10, 2155–2158.
[21] H. Man, K. Kedziora, J. Kulig, A. Frank, I. Lavandera, V. Gotor-Fernandez,
D. Rother, S. Hart, J. P. Turkenburg, G. Grogan, Top. Catal. 2014, 57, 356–
365.
[22] I. Lavandera, A. Kern, B. Ferreira-Silva, A. Glieder, S. de Wildeman, W.
Kroutil, J. Org. Chem. 2008, 73, 6003–6005.
[23] J. Kulig, A. Frese, W. Kroutil, M. Pohl, D. Rother, Biotechnol. Bioeng. 2013,
110, 1838–1848.
F. Hollmann, I. W. C. E. Arends, D. Holtmann, Green Chem. 2011, 13, 2285–
2314.
S. K. Padhi, D. Titu, N. G. Pandian, A. Chadha, Tetrahedron 2006, 62, 5133–
5140.
S. Y. Tang, R. A. Bourne, R. L. Smith, M. Poliakoff, Green Chem. 2008, 10,
268–269.
A. Zadlo, D. Koszelewski, F. Borys, R. Ostaszewski, ChemBioChem 2015,
16, 677–682.
[15] M. Schuler, F. Silva, C. Bobbio, A. Tessier, V. Gouverneur, Angew. Chem.
Int. Ed. 2008, 47, 7927–7930; Angew. Chem. 2008, 120, 8045.
[16] R. Zibuck, J. M. Streiber, J. Org. Chem. 1989, 54, 4717–4719.
[17] W. Kroutil, H. Mang, K. Edegger, K. Faber, Curr. Opin. Chem. Biol. 2004, 8,
120–126.
[18] W. Stampfer, B. Kosjek, C. Moitzi, W. Kroutil, K. Faber, Angew. Chem. Int.
Ed. 2002, 41, 1014–1017; Angew. Chem. 2002, 114, 1056.
[19] K. Goldberg, K. Schroer, S. Lütz, A. Liese, Appl. Microbiol. Biotechnol. 2007,
76, 249–255.
[24] M. Hall, B. Hauer, R. Stuermer, W. Kroutil, K. Faber, Tetrahedron: Asymmetry
2006, 17, 3058–3062.
[25] W. Stampfer, B. Kosjek, K. Faber, W. Kroutil, J. Org. Chem. 2003, 68, 402–
406.
[26] C. Baker-Glenn, N. Hodnett, M. Reiter, S. Ropp, R. Ancliff, V. Gouverneur,
J. Am. Chem. Soc. 2005, 127, 1481–1486.
Received: November 19, 2015
Published Online: January 12, 2016
Eur. J. Org. Chem. 2016, 1007–1011
www.eurjoc.org
1011
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim