Reduction processes biocatalyzed by Vigna unguiculata

Article abstract of DOI:10.1016/j.tetasy.2010.03.005

Whole cells from the Brazilian beans feijao de corda (Vigna unguiculata) have been employed as biocatalysts in different bioreduction processes. Good to excellent selectivities can be obtained in the reduction of aromatic and aliphatic ketones, as well as β-ketoesters, depending on the conversions and the chemoselectivity on the substrate structure. This biocatalyst was also able to reduce the nitro moiety of different aromatic nitro compounds, showing as well enoate reductase activity, and chemoselectively catalyzing the double bond reduction of 4-phenyl-3-buten-2-one with moderate conversion.

Full text of DOI:10.1016/j.tetasy.2010.03.005

Tetrahedron: Asymmetry 21 (2010) 566–570
Contents lists available at ScienceDirect
Tetrahedron: Asymmetry
journal homepage: www.elsevier.com/locate/tetasy
Reduction processes biocatalyzed by Vigna unguiculata
Ayla M. C. Bizerra a,b, Gonzalo de Gonzalo , Iván Lavandera , Vicente Gotor-Fernández ,
b
b
b
a
a
a,
b,*
Marcos Carlos de Mattos , Maria da Conceicão F. de Oliveira , Telma L. G. Lemos *, Vicente Gotor
Departamento de Química Orgânica e Inorgânica, Laboratório de Biotransformações e Produtos Naturais (LBPN), Universidade Federal do Ceará, 60451-970 Fortaleza, Ceará, Brazil
Departamento de Química Orgánica e Inorgánica, Instituto Universitario de Biotecnología de Asturias, Universidad de Oviedo, c/ Julián Clavería 8, 33006 Oviedo, Spain
a
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Whole cells from the Brazilian beans feijão de corda (Vigna unguiculata) have been employed as biocata-
lysts in different bioreduction processes. Good to excellent selectivities can be obtained in the reduction
of aromatic and aliphatic ketones, as well as b-ketoesters, depending on the conversions and the che-
moselectivity on the substrate structure. This biocatalyst was also able to reduce the nitro moiety of dif-
ferent aromatic nitro compounds, showing as well enoate reductase activity, and chemoselectively
catalyzing the double bond reduction of 4-phenyl-3-buten-2-one with moderate conversion.
Ó 2010 Elsevier Ltd. All rights reserved.
Received 2 February 2010
Accepted 4 March 2010
Available online 10 April 2010
1
. Introduction
Nowadays, the preparation of enantioenriched secondary alco-
other authors have described the use of flavoenzymes for the
hydrogenation of dinitro compounds.
9
Plants have been considered as enzymatic systems suitable for
being employed in biocatalysis. Most of the reactions catalyzed
by plants are redox processes (reduction of aldehydes and ketones,
oxidation of racemic alcohols), but they are also able to catalyze
hols has become of increasing interest due to their numerous
applications as chiral building blocks in pharmaceutical and
(
agro)chemical industry in addition to their activity as pheromones
1
10
and flavor or aroma enhancing compounds. Different methodolo-
gies have been developed in order to synthesize these important
compounds, the stereoselective reduction of ketones being one
of the most widely employed methods, since it allows the produc-
tion of these derivatives in quantitative yields.3 Over the last few
years, biocatalysis has emerged as a reliable alternative to conven-
tional chemical methods due to the high selectivities achieved
while using mild, economically viable and eco-compatible condi-
hydrolyses of esters and acylations of alcohols. Immobilized
plant cell cultures as well as whole cell tissues have the advantages
of being available at low cost, mild reaction conditions and easy re-
moval after use.
2
In some previous studies performed by our research groups,
several biocatalytic systems obtained from the Brazilian biodiver-
sity have been analyzed and employed in the reduction of prochiral
1
1
ketones and the acylation of racemic alcohols. Herein, we report
the use of whole cells of Vigna unguiculata as a biocatalyst in
different organic synthetic reactions. The so-called feijão de corda
or feijão caupi belongs to the Phaseoleae family and grows predom-
inantly in the North and Northeast of Brazil, due to its resistance to
high temperatures and water stress. This legume is of high interest
in the Brazilian diet, since it is an important source of proteins (23–
25% on average) and carbohydrates with high contents of fiber,
vitamins and minerals. Herein we also show that this preparation
is able to reduce carbonyl, nitro and alkene compounds, demon-
strating its potential as a catalyst in organic synthesis.
4
tions. Optically active sec-alcohols can be obtained by employing
a variety of biocatalytic methods,5 for example, lipase-catalyzed
kinetic resolutions, but in the last few years, the synthesis of enan-
tiopure secondary alcohols via reduction of ketones or oxidative
kinetic resolutions of racemic alcohols using alcohol dehydrogen-
ases (ADHs) has gained increasing interest.6
The selective reduction of aromatic nitro compounds is a useful
transformation applied to the synthesis of amines, important inter-
mediates in the production of pharmaceuticals and other high
1
b,7
added value derivatives.
This reaction is also of interest in bio-
remediation processes. For example, nitrophenols are widely used
as industrial intermediate compounds, but they are environmental
pollutants due to their toxicity and resistance to biodegradation.
Several methodologies have been described to perform the chem-
ical reduction of nitro derivatives. Enzymatically, examples of this
process have been reported employing nitroreductases, whereas
2
. Results and discussion
8
Our initial efforts were devoted to the use of cells of V. unguic-
ulata as a biocatalyst in the reduction of a group of aromatic
ketones. Acetophenone 1a was chosen as a model substrate for
the optimization of the reaction conditions. The first set of biore-
ductions was performed at 30 °C for 72 h in order to determine
the best reaction medium for this process as shown in Table 1
*
Corresponding author.
E-mail address: vgs@fq.uniovi.es (V. Gotor).
0
957-4166/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetasy.2010.03.005

A. M. C. Bizerra et al. / Tetrahedron: Asymmetry 21 (2010) 566–570
567
Table 1
Table 2
Vigna unguiculata biocatalyzed reduction of 1a to (S)-1b in aqueous media at different
Bioreductions of substituted acetophenones catalyzed by whole cells of Vigna
unguiculata (t = 72 h)
reaction conditionsa
a
O
Vigna unguiculata
Reaction medium
OH
O
V. unguiculata
OH
i
R1
H O/ 2% PrOH
R1
2
T(°C)/ 250 rpm
3
0°C/ 250 rpm
72 h
72 h
X
X
1
a
(S)-1b
cb (%)
(S)-2-8b
(
2
-12a
R)-9-12b
Entry
1
% Cosolvent
T (°C)
eeb (%)
R1
2–12bb (%)
ee (%)
b
Entry
Ketone
X
None
None
2% PrOH
2% DMSO
5% PrOH
10% PrOH
30% PrOH
2% PrOH
2% PrOH
30
30
30
30
30
30
30
20
37
45
34
31
35
33
32
24
63
35
28
19
92
92
P99
96
P99
P99
n.d.
P99
P99
98
c
1
2
3
4
5
6
7
8
9
2a
3a
4a
5a
6a
7a
8a
9a
4 -MeO
0
H
H
H
H
H
H
H
H
Cl
Cl
Cl
5
86
5
P99 (S)
P99 (S)
P99 (S)
96 (S)
P99 (S)
87 (S)
P99 (S)
P99 (R)
P99 (R)
P99 (R)
89 (R)
2
i
3 -MeO
0
3
4
5
6
7
8
9
0
2 -MeO
i
4 -Me
0
13
11
13
24
56
69
78
78
i
2 -Me
0
0
i
i
4 - Pr
i
4 -Cl
0
i
3 -Br
0
c
0
i
10a
11a
12a
4 -Cl
1
0
2% PrOH
c
0 0
2 ,4 -Cl
10
c
0 0
3 ,4 -Cl
n.d. not determined.
11
a
Reaction time, 72 h. For other reaction conditions see the Experimental.
Conversions (c) and enantiomeric excesses (ee) were determined by HPLC or GC.
Reaction performed using a Tris–HCl 50 mM buffer (pH 7.5).
a
b
c
For more detailed reaction conditions, see the Section 4.
b
Conversions (c) and enantiomeric excesses (ee) were determined by HPLC or
GC. Absolute configuration of the alcohol is in parentheses.
c
Absolute configuration is reversed due to a change in the substituent priority
according to the CIP sequence rules.
(
entries 1–4). When the bioreduction was performed in water, 34%
of the Prelog alcohol (S)-1b was obtained with 92% ee (entry 1).
The use of a Tris–HCl buffer at pH 7.5 led to a slight decrease in
the enzymatic activity (entry 2). Then, we decided to test some
lower extent. While ketones 5a and 6a were reduced with
conversions close to 13% to the corresponding enantiopure (S)-
alcohols (entries 4 and 5), 4 -isopropylacetophenone 7a led to
ꢀ1
0
cosolvents when water was employed. The addition of 2% vv
i
PrOH resulted in enantiopure (S)-1b with a 35% conversion (entry
(S)-7b with the same conversion but lower enantiomeric purity
(ee = 87%), indicating that the presence of bulkier alkyl chains
had a negative effect on the biocatalyst selectivity (entry 6). Hal-
ogenated ketones were also tested obtaining better results. Thus,
3
). When DMSO was employed in the same amount (entry 4), the
enantiomeric purity of the resulting alcohol was lower, while no
appreciable change was observed in the biocatalyst activity.
i
0
Once water containing PrOH was selected as the best reaction
4 -chloroacetophenone was converted to (S)-8b with an excellent
medium for the biotransformations, we analyzed the effect of this
cosolvent on the biocatalytic properties of V. unguiculata. Bioreduc-
tions of 1a were carried out employing different concentrations of
enantiomeric excess and 24% conversion after 72 h (entry 7). The
bromo derivative 9a (entry 8) led to the opposite enantiopure
(R)-9b with good conversion (c = 56%).
i
ꢀ1 i
PrOH, as shown in entries 5–7. The use of 5% vv
PrOH did not
A set of a-chloro ketones was also tested as possible substrates
alter the properties of the enzyme, producing enantiopure (S)-1b
with 32% conversion (entry 5). Higher cosolvent concentrations
led to a progressive deactivation of the biocatalyst, as indicated
in entries 6 and 7. This effect was especially dramatic when adding
for the enzymatic processes. Reduction of these compounds led to
the formation of the corresponding halohydrins, versatile interme-
1
2
diates in the preparation of bioactive compounds. When 2-chlo-
roacetophenone 10a was reduced in the presence of V. unguiculata
(entry 9), the Prelog alcohol (R)-10b was obtained with good yield
ꢀ1 i
3
0% vv PrOH, since no reduction was observed under these con-
0
0
ditions. Temperature was also analyzed as a key parameter in the
acetophenone bioreduction (entries 8–10). When it was carried
out at 20 °C, the same activity and selectivity were achieved than
working at 30 °C (entry 8). An increase in temperature to 37 °C (en-
try 9), led to a slight deactivation of the biocatalyst, while at 45 °C
and excellent selectivity. The 2,2 ,4 -trichloro derivative 11a (entry
10) also led to enantiopure (R)-11b with high conversion (c = 78%),
while the bioreduction of ketone 12a (entry 11) occurred with the
same yield, but with a lower selectivity [(R)-12b was obtained with
ee = 89%].
(
entry 10), the loss of the activity was higher (c = 19%), without sig-
Aliphatic ketones and b-ketoesters were also tested as suitable
substrates for V. unguiculata (Table 3). Bioreduction of 2-octanone
13a led to the formation of enantiopure (S)-13b with low conver-
sion (c = 16%) after 72 h (entry 1). Enantiopure (S)-2-undecanol
14b could be obtained with a slightly higher conversion in the
same reaction time, as shown in entry 2. Whole cells were tested
in the reduction of b-ketoesters which led to the corresponding
chiral b-hydroxyesters, important synthons in organic chemistry.13
Ethyl acetoacetate 15a was reduced with high conversion (c = 83%
after 48 h, entry 3) leading to enantiopure (S)-15b, indicating that
V. unguiculata showed a high activity for this compound (complete
conversion was achieved after 72 h). A similar result was obtained
in the bioreduction of 16a (entry 4). After 48 h, 88% of (R)-16b with
99% ee was obtained. This alcohol is a useful chiral building block
nificant changes in the enantiomeric purity of (S)-1b.
After establishing the best reaction conditions for the biore-
duction of 1a, we extended our study to other acetophenone
derivatives, as indicated in Table 2. For most of the ketones stud-
ied, the expected Prelog product was formed, with the exception
of substrate 9a (3’-bromo), where the anti-Prelog alcohol [(R)
configuration] was obtained, indicating that for this compound,
different alcohol dehydrogenase(s) could act in the enzymatic
system. Firstly, we analyzed the effect of an electron-donating
group such as methoxy, observing that the position of this moi-
ety greatly affected the enzymatic activity. While the 4 - and
2
low conversions after 72 h (entries 1 and 3), (S)-3b could be ob-
tained in 86% yield (entry 2). In all these processes, alcohols were
isolated in enantiopure form. Substituted acetophenones with an
alkyl group in the aromatic ring were also reduced although to a
0
0
-methoxy derivatives 2a and 4a, respectively, showed very
1
4
for the synthesis of different pharmaceuticals.
V. unguiculata cells were tested in the reduction of acetophe-
nones presenting in their structure a nitro substituent in the aro-

5
68
A. M. C. Bizerra et al. / Tetrahedron: Asymmetry 21 (2010) 566–570
Table 3
nitro compounds as potential substrates for our biocatalytic sys-
tem (Scheme 1). When nitrobenzene 20a was treated in the pres-
ence of whole cells of V. unguiculata, it was possible to obtain
Bioreduction of aliphatic ketones and b-ketoesters employing Vigna unguiculata as a
biocatalysta
Vigna unguiculata
H2O/2% PrOH
1
2
6% of aniline 20c after 72 h. We analyzed 4-nitrophenol 21a and
-nitrophenol 22a as substrates, but no reaction was observed
O
i
OH
R2
R2
R1
R1
even after long reaction times, thus showing that electron-donor
substituents disfavored this biotransformation. This fact could ex-
plain why amino alcohols were not obtained with nitro ketones
17–19a. 4-Nitrophenyl acetate 23a was also studied, leading after
72 h to the complete formation (c P99%) of the hydrolyzed prod-
uct 4-nitrophenol 21a. When we carried out a blank reaction in
the absence of biocatalyst, only 36% of 23a was hydrolyzed, indi-
cating that V. unguiculata was also able to perform the acetate
hydrolysis with a moderate rate. Benzonitrile 24a was finally em-
ployed, but the whole cells were not able to hydrolyze the nitrile
moiety.
3
0ºC/ 250 rpm
1
3-16a
(S)-13-15b
(
R)-16b
1
2
1
1
1
1
3a R =-CH2(CH2)4CH3 R =H
1
2
4a R =-CH2(CH2)7CH3 R =H
1
2
5a R =-CH2COOCH3 R =H
1
2
6a R =-CH2COOCH3 R =Cl
cb (%)
eeb (%)
Entry
Substrate
t (h)
1
2
3
13a
14a
15a
16a
72
72
48
48
16
19
83
88
P99 (S)
P99 (S)
P99 (S)
P99 (R)
c
V. unguiculata
4
NO
2
i
NH
2
H O/2% PrOH
2
a
For reaction details, see the Section 4.
Conversion (c) and enantiomeric excesses (ee) were determined by HPLC or GC.
b
30°C/ 250 rpm
72 h
Absolute configuration of the alcohol is in parentheses.
c
20a
20c
Absolute configuration is reversed due to a change in the substituent priority
according to the CIP sequence rules.
V. unguiculata
NO2
i
NO2
H O/2% PrOH
O
2
3
0°C/ 250 rpm
matic ring, a group also sensitive in the reduction processes, in or-
der to analyze the chemoselectivity of these reactions (Table 4).
Thus, the bioreduction of 4 -nitroacetophenone 17a led after 72 h
O
HO
72 h
23a
21a
0
to the formation of two different products: the expected enantio-
pure nitro alcohol (R)-17b with 42% conversion, and also the amino
ketone obtained from the reduction of the nitro group 17c, was ob-
tained in 54% yield (entry 1). Thus, this biocatalytic system pre-
sented enzyme(s) able to reduce the nitro moiety into the
Scheme 1. V. unguiculata-catalyzed processes using nitro compounds 20a and 23a
ꢀ
1 i
as substrates in aqueous media containing 2% vv
PrOH.
The asymmetric alkene reduction is an attractive reaction for
organic chemists, as it offers the possibility of creating two adja-
3
cent sp centers in a single step. Enoate reductases, members of
0
corresponding amine. Bioreduction of 3 -nitroacetophenone 18a
15
the ‘old yellow family’, catalyze this transformation in nature.
0
occurred with low conversion compared to the 4 -nitro derivative
These enzymes are widely found in microorganisms and plants.
For this reason, we have started a preliminary study on this activity
employing 4-phenyl-3-buten-2-one 25a as a model substrate in or-
der to determine the ability of V. unguiculata to reduce double
bonds (Scheme 2). After 72 h, 41% of 4-phenylbutan-2-one 25b
was obtained while only traces (less than 3%) of the other possible
reduction products, 4-phenyl-3-buten-2-ol 25c and 4-phenylb-
utan-2-ol 25d, were observed in the reaction media, showing that
this activity was present in our preparation.
(
entry 2). Only 14% yield of enantiopure (S)-18b was achieved,
0
while 3 -aminoacetophenone 18c was formed in 8% yield. Lower
activity was measured for the 2 -nitro derivative 19a (entry 3),
0
leading to 4% of enantiopure (S)-19b and 8% of 19c. This fact was
probably due to steric hindrance. No amino alcohol compounds
were detected in any case. It is important to note that the 4’-nitro
derivative was reduced to the anti-Prelog alcohol (R)-17b, present-
ing the same behavior as substrate 9a.
Table 4
O
a
Bioreductions of nitroacetophenones catalyzed by Vigna unguiculata (t = 72 h)
O
V. unguiculata
OH
*
O
i
H O/2% PrOH
2
+
25b (41%)
3
0°C/ 250 rpm
OH
O N
72 h
O N
H N
O
V. unguiculata
2
2
2
i
H O/ 2% PrOH
2
(
(
R)-17b
S)-18-19b
1
7-19a
17-19c
30°C/ 250 rpm
72 h
1
1
1
7a 4'-NO2
8a 3'-NO2
9a 2'-NO2
25c
(<3%)
OH
25a
Entry
Ketone
17–19bb (%)
eeb (%)
17–19cb (%)
2
5d (<3%)
1
2
3
17a
18a
19a
42
14
4
P99 (R)
P99 (S)
P99 (S)
54
8
8
Scheme 2. Bioreduction of 4-phenyl-3-buten-2-one 25a catalyzed by whole cells of
ꢀ
1 i
V. unguiculata in aqueous media containing 2% vv
PrOH.
a
For reaction conditions, see Section 4.
Conversions (c) and enantiomeric excesses (ee) were calculated by HPLC or GC.
b
3
. Conclusions
Since we found unusual nitro reductive activity when reducing
nitro ketones 17–19a using whole cells of V. unguiculata to obtain
the corresponding amines, we decided to test different aromatic
We have shown V. unguiculata to be an excellent stereo- and
chemoselective biocatalyst for the production of interesting organ-

A. M. C. Bizerra et al. / Tetrahedron: Asymmetry 21 (2010) 566–570
569
ic compounds. Whole cells from this vegetal source have been em-
ployed as a biocatalytic system to different reduction processes.
After optimizing the reaction conditions, that is, the amount of
cosolvent and the temperature using acetophenone as a model
substrate, this biocatalyst has shown a remarkable ability to reduce
acetophenone derivatives with high to excellent stereoselectivites
depending on the substrate structure. In most of the cases, the Pre-
log reduction products were obtained. Enantiopure (R)-b-chloroal-
cohols, interesting chiral synthons, could be obtained with good
conversions. Aliphatic ketones were also reduced with total selec-
tivity, while the bioreduction of b-ketoesters led to the formation
of the corresponding enantiopure Prelog b-hydroxyesters with
excellent conversions. Furthermore, V. unguiculata was able to re-
duce nitro groups to the corresponding amines when nitrobenzene
and nitroacetophenones were employed as substrates, while no
reaction was observed in the case of nitrophenols. Whole cells of
V. unguiculata contained at least one enoate reductase, as this sys-
tem was able to catalyze preferentially the reduction of the double
bond of 4-phenyl-3-buten-2-one with regard to the alcohol
formation.
in water containing concentrated HCl and subsequent treatment
with an aqueous solution of NaOH (yields from 60% to 74%).17
The absolute configurations of alcohols (S)-1–8b, (S)-13–15b,
(S)-18–19b, (R)-9–12b and (R)-16–17b obtained from the V.
unguiculata-catalyzed reductions were established by making a
comparison of the retention times on GC with previously published
1
1a,c,18
data.
4.2. Plant material
V. unguiculata beans were collected at the planting in rural up-
state (Miraíma, CE, Brazil). Bean seeds were rinsed with 5% aque-
ous solution of sodium hypochlorite and distilled water and
dried completely at room temperature, after which, the beans were
ground in order to obtain a fine powder that was used as a
biocatalyst.
4.3. General procedure for the V. unguiculata biocatalyzed
reductions of ketones 1–19a and 25a, nitro derivatives 20–23a
and benzonitrile 24a
In a typical experiment, substrates 1–25a (5.0 mg) were added
to a suspension of V. unguiculata powder (1.0 g) in 3.0 mL of dis-
4
4
. Experimental
ꢀ1 i
tilled water containing 2% vv
PrOH. Reactions were shaken at
.1. General
250 r.p.m. at the selected temperatures for the corresponding time.
Once finished, the crude reactions were extracted with EtOAc
(3 ꢁ 5 mL), the organic layers were combined, dried onto Na SO
Chemical reactions were monitored by analytical TLC, per-
2
4
formed on Merck Silica Gel 60 F254 plates and visualized by UV
irradiation. Flash chromatography was carried out with silica gel
6
and the solvent was removed under reduced pressure. Samples ob-
tained were analyzed by GC and/or HPLC in order to determine the
conversions and the enantiomeric excesses of the final products.
0 (230–240 mesh, Merck). IR spectra were recorded on a Per-
kin–Elmer 1720-X infrared Fourier transform spectrophotometer
using KBr pellets. UV spectra were performed on a Perkin–Elmer
Acknowledgments
1
13
Lambda Bio10 UV/Vis Spectrophotometer. H NMR, C NMR and
DEPT spectra were recorded with tetramethylsilane (TMS) as the
This work was supported by the Ministerio de Ciencia e Innova-
ción of Spain (Project CTQ 2007-61126). G.de G. and V.G.F. thank
MICINN for personal grants (Juan de la Cierva and Ramon y Cajal
program, respectively). I.L. thanks the Principado de Asturias for
personal funding (Clarín Program). The authors thank the Brazilian
and Spanish agencies CNPq, FUNCAP, PRONEX, CAPES-DGU (Pro-
cess: 149/07) for fellowships and financial support.
1
internal standard with a Bruker AC-300 DPX ( H: 300.13 MHz;
1
3
+
+
C: 75.5 MHz) spectrometer. APCI and ESI using a Hewlett–Pack-
+
ard 1100 chromatograph mass detector or EI with a Hewlett–
Packard 5973 mass spectrometer were used to record mass spectra
(
MS). GC analyses were performed on a Hewlett–Packard 6890 Ser-
ies II chromatograph equipped with a Restek RtbDEXse (30 m ꢁ
.25 mm ꢁ 0.25 m, 1 bar N ) or a Varian CP-Chiralsil-DEX CB
25 m ꢁ 0.32 mm ꢁ 0.25 m, 1 bar N ) for chiral determinations
or
HP-1 (crosslinked methyl siloxane, 30 m ꢁ 0.25 mm ꢁ
.25 m, 1.0 bar N ) from Hewlett–Packard for measuring the con-
versions values. For all the analyses, the injector temperature is
25 °C and the FID temperature is 250 °C. HPLC analyses were
0
l
2
(
l
2
References
a
1.
(a) Daubmann, T.; Hennemann, H. G.; Rosen, T. C. Chem. Ing. Tech. 2006, 78,
49–255; (b) Breuer, M.; Ditrich, K.; Habicher, T.; Hauer, B.; Kesseler, M.;
Stürmer, R.; Zelinski, T. Angew. Chem., Int. Ed. 2004, 43, 788–824.
2. See for example: (a) Mao, J. C.; Xie, G. L. Curr. Org. Chem. 2009, 13, 1553–1564;
b) Jones, S.; Valette, D. Org. Lett. 2009, 11, 5358–5361; (c) Tomizawa, M.;
0
l
2
2
2
(
developed with a Hewlett–Packard 1100 LC liquid chromatograph
Shibuya, M.; Iwabuchi, Y. Org. Lett. 2009, 11, 1829–1831; (d) Vedjes, E.; Jure, M.
Angew. Chem., Int. Ed. 2005, 44, 3974–4001; (e) Robinson, D. E. J. E.; Bull, S. D.
Tetrahedron: Asymmetry 2003, 14, 1407–1446.
equipped with Chiralcel OB-H (0.46 ꢁ 25 cm), a Chiralpak IA
(
0.46 ꢁ 25 cm) or a Chiralpak AS (0.46 ꢁ 25 cm) chiral columns
purchased from Daicel.
3. (a) Baratta, W.; Ballico, M.; Del Zotto, A.; Siega, K.; Magnolia, S.; Rigo, P. Chem.
Eur. J. 2008, 14, 2557–2563; (b) Enthaler, S.; Spilker, B.; Erre, G.; Junge, K.; Tse,
M. K.; Beller, M. Tetrahedron 2008, 64, 3867–3876; (c) Wu, X.; Xiao, J. Chem.
Commun. 2007, 2449–2466; (d) Ikariya, T.; Blacker, A. J. Acc. Chem. Res. 2007,
40, 1300–1308.
Ketones 1–4a, 6a, 8–9a, 13–18a, 25a–b, alcohol 25d, nitro com-
pounds 20–23a, aromatic amines 20–22c, and benzonitrile 24a
were products from Sigma–Aldrich, while compounds 5a, 7a, 10–
4.
(a) Modern Biocatalysis; Fessner, W.-D., Anthonsen, T., Eds.; Wiley-VCH:
Weinheim, 2009; (b) Patel, R. N. Coord. Chem. Rev. 2008, 252, 659–701; (c)
Woodley, J. M. Trends Biotechnol. 2008, 26, 321–327; (d) Asymmetric Organic
Synthesis with Enzymes; Gotor, V., Alfonso, I., García-Urdiales, E., Eds.; Wiley-
VCH: Weinheim, 2008; (e) Hydrolases in Organic Synthesis: Regio- and
Stereoselective Transformations; Bornscheuer, U. T., Kazlauskas, R. J., Eds., 2nd
ed.; Wiley-VCH: Weinheim, 2006.
1
2a and 19a were purchased from Alfa Aesar. All other reagents
and solvents were of the highest quality from Sigma–Aldrich-Flu-
ka. All the racemic alcohols (±)-1–19b and 25d were prepared by
chemical reduction of the corresponding ketones employing NaBH
4
in dry methanol at room temperature. In all cases, high yields were
achieved (higher than 80%). When necessary, in order to measure
the enantiomeric excesses, alcohols were acetylated with acetic
anhydride and Et N in CH Cl to obtain the corresponding racemic
3 2 2
acetates, which were isolated in quantitative yields in all cases. 4-
5. Some examples of enzymatic synthesis of chiral alcohols: (a) Lee, E. Y.
Biotechnol. Lett. 2008, 30, 1509–1514; (b) Ghanem, A. Tetrahedron 2007, 63,
1721–1754; (c) Gotor, V. J. Biotechnol. 2002, 96, 35–42; (d) Griengl, H.; Schwab,
H.; Fechter, M. Trends Biotechnol. 2000, 6, 252–256.
6. For recent bibliography, see: (a) Matsuda, T.; Yamanaka, R.; Nakamura, K.
Tetrahedron: Asymmetry 2009, 20, 513–557; (b) Nakamura, K.; Matsuda, T. In
Asymmetric Organic Synthesis with Enzymes; Gotor, V., Alfonso, I., García-
Urdiales, E., Eds.; Wiley-VCH: Weinheim, 2008; pp 193–228; (c) Goldberg, K.;
Schroer, K.; Lütz, S.; Liese, A. Appl. Microb. Biotechnol. 2007, 76, 249–255; (d) De
Wildeman, S. M. A.; Sonke, T.; Schoemaker, H. E.; May, O. Acc. Chem. Res. 2007,
Phenyl-3-buten-2-ol 25c was prepared following the procedure
4
described in the literature, treating ketone 25a with NaBH in a
mixture of MeOH–THF 1:10.16 Aminoketones 17–19c were synthe-
sized by reducing the corresponding nitroketones 17–19a with Sn

5
70
A. M. C. Bizerra et al. / Tetrahedron: Asymmetry 21 (2010) 566–570
0, 1260–1266; (e) Moore, J. C.; Pollard, D. J.; Kosjek, B.; Devine, P. N. Acc. Chem.
4
M. C.; Cordell, G. A.; Braz-Filho, R.; Lemos, T. L. G. J. Mol. Catal. B: Enzym. 2009,
57, 78–82; (c) Machado, L. L.; Lemos, T. L. G.; de Mattos, M. C.; de Oliveira, M. C.
F.; de Gonzalo, G.; Gotor-Fernández, V.; Gotor, V. Tetrahedron: Asymmetry 2008,
19, 1419–1424; (d) Machado, L. L.; Monte, F. J. Q.; de Oliveira, M. C. F.; de
Mattos, M. C.; Lemos, T. L. G.; Gotor-Fernández, V.; de Gonzalo, G.; Gotor, V. J.
Mol. Catal. B: Enzym. 2008, 55, 130–133; (e) Cordell, G. A.; Lemos, T. L. G.;
Monte, F. J. Q.; de Mattos, M. C. J. Nat. Prod. 2007, 70, 478–492.
12. (a) Patel, R. N. Enzyme Microb. Technol. 2002, 31, 804–826; (b) Hamada, H.;
Miura, T.; Kumobayashi, H.; Matsuda, T.; Harada, K.; Nakamura, K. Biotechnol.
Lett. 2001, 23, 1603–1606.
Res. 2007, 40, 1412–1419; (f) Kroutil, W.; Mang, H.; Edegger, K.; Faber, K. Curr.
Opin. Chem. Biol. 2004, 8, 120–126.
(a) Peng, F. Z.; Shao, Z. H. J. Mol. Catal. A: Chem. 2008, 285, 1–13; (b) Melchiorre,
P.; Marigo, M.; Carlone, A.; Bartoli, G. Angew. Chem., Int. Ed. 2008, 47, 6138–6171.
For some recent examples, see: (a) de Noronha, R. G.; Romão, C. C.; Fernandes,
A. C. J. Org. Chem. 2009, 74, 6960–6964; (b) Li, B.; Xu, Z. J. Am. Chem. Soc. 2009,
7
.
.
8
131, 16380–16382; (c) Spencer, J.; Rathnam, R. P.; Patel, H.; Anjum, N.
Tetrahedron 2008, 64, 10195–10200; (d) MacLaughlin, M. A.; Barnes, D. M.
Tetrahedron Lett. 2006, 47, 9095–9097.
9
.
(a) Dai, R.; Chen, J.; Lin, J.; Xiao, S.; Chen, S.; Deng, Y. J. Hazard. Mater. 2009, 170,
13. Shimizu, S.; Kataoka, M.; Kita, K. J. Mol. Catal. B: Enzym. 1998, 5, 321–325.
14. Kizaki, N.; Yasohara, Y.; Hasegawa, J.; Wada, M.; Kataoka, M.; Shimizu, S. Appl.
Microbiol. Technol. 2001, 55, 590–595.
1
41–143; (b) Couch, G. D.; Burke, P. J.; Knox, R. J.; Moody, C. J. Tetrahedron 2008,
64, 2860–2864; (c) Korbekandi, H.; Mather, P.; Gardiner, J.; Stephens, G. Enzyme
Microb. Technol. 2008, 42, 308–314; (d) Pacheco, A. O.; Kagohara, E.; Andrade, L.
H.; Comasseto, J. V.; Crusius, I. H.-S.; Paula, C. R.; Porto, A. L. M. Enzyme Microb.
Technol. 2007, 42, 65–69.
15. For some recent references on enoate reductases, see: (a) Stueckler, C.; Reiter,
T. C.; Baudendistel, N.; Faber, K. Tetrahedron 2010, 66, 663–667; (b) Kumar
Padhi, S.; Bougioukou, D. J.; Stewart, J. D. J. Am. Chem. Soc. 2009, 131, 3271–
3280; (c) Stuermer, R.; Hauer, B.; Hall, M.; Faber, K. Curr. Opin. Chem. Biol. 2007,
11, 203–213; (d) Müller, A.; Hauer, B.; Rosche, B. Biotechnol. Bioeng. 2007, 98,
22–29; (e) Swiderska, M. A.; Stewart, J. D. J. Mol. Catal. B: Enzym. 2006, 42, 52–
54.
1
1
0. (a) Lacheretz, R.; Gomez Pardo, D.; Cossy, J. Org. Lett. 2009, 11, 1245–1248; (b)
Bohman, B.; Cavonius, L. R.; Unelius, C. R. Green Chem. 2009, 11, 1900–1905; (c)
Orden, A. A.; Magallanes-Noguera, C.; Agostini, E.; Kurina-Sanz, M. J. Mol. Catal.
B: Enzym. 2009, 61, 216–220; (d) Yadav, J. S.; Subba Reddy, B. V.; Sreelakshmi,
C.; Bhaskar Rao, A. Synthesis 2009, 1881–1885; (e) Utsukihara, T.; Sato, M.;
Kawamoto, M.; Itoh, K.; Sakamaki, H.; Kuniyoshi, M.; Horiuchi, C. A. J. Mol.
Catal. B: Enzym. 2007, 48, 59–63; (f) Yadav, J. S.; Nanda, S.; Reddy, P. T.; Rao, A.
B. J. Org. Chem. 2002, 67, 3900–3903.
16. Varma, R. S.; Kabalka, G. W. Synth. Commun. 1985, 15, 985–990.
17. Jones, A. G. J. Chem. Educ. 1975, 52, 668–670.
18. (a) Vieira, G. A. B.; Lemos, T. L. G.; de Mattos, M. C.; de Oliveira, M. C. F.; Melo, V.
M. M.; de Gonzalo, G.; Gotor-Fernández, V.; Gotor, V. Tetrahedron: Asymmetry
2009, 20, 214–219; (b) Bisogno, F. R.; Lavandera, I.; Kroutil, W.; Gotor, V. J. Org.
Chem. 2009, 74, 1730–1732; (c) Zhu, D.; Hyatt, B. A.; Hua, L. J. Mol. Catal. B:
Enzym. 2009, 56, 272–276.
1. (a) Barros-Filho, B. A.; de Oliveira, M. C. F.; Lemos, T. L. G.; de Mattos, M. C.; de
Gonzalo, G.; Gotor-Fernández, V.; Gotor, V. Tetrahedron: Asymmetry 2009, 20,
1
057–1061; (b) Fonseca, A. M.; Monte, F. J. Q.; de Oliveira, M. C. F.; de Mattos,