Enantioselective ketoester reductions in water: A comparison between microorganism-and ruthenium-catalyzed reactions

Article abstract of DOI:10.1016/j.tetasy.2010.05.014

In the search for green chemistry methods for the enantioselective reduction of ketoesters Saccharomyces cerevisiae-and ruthenium-catalyzed reactions in water have been investigated. The highest enantiomeric excesses for the reduction of α-and β-ketoesters have been obtained by S. cerevisiae. Chiral ruthenium catalysts are active for the reduction of all ketoesters with low to moderate enantioselectivities depending on the nature of the substrate and ligand. Interestingly, for several substrates both enantiomers of the hydroxyesters have been obtained according either to the catalytic method or to the structure of the ligand.

Full text of DOI:10.1016/j.tetasy.2010.05.014

Tetrahedron: Asymmetry 21 (2010) 1211–1215
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Tetrahedron: Asymmetry
journal homepage: www.elsevier.com/locate/tetasy
Enantioselective ketoester reductions in water: a comparison between
microorganism- and ruthenium-catalyzed reactions
b, ,à
Saoussen Zeror b, Jacqueline Collin a, , Jean-Claude Fiaud a, , Louisa Aribi Zouioueche
*
*
a Equipe de Catalyse Moléculaire, ICMMO, UMR 8182, Université Paris-Sud, 91405 Orsay, France
b Groupe de Synthèse Asymétrique et Biocatalyse, LCOA, Université Badji Mokhtar, 23000 Annaba, Algeria
a r t i c l e i n f o
a b s t r a c t
Article history:
In the search for green chemistry methods for the enantioselective reduction of ketoesters Saccharomyces
cerevisiae- and ruthenium-catalyzed reactions in water have been investigated. The highest enantiomeric
Received 14 December 2009
Accepted 5 May 2010
Available online 14 June 2010
excesses for the reduction of
a- and b-ketoesters have been obtained by S. cerevisiae. Chiral ruthenium
catalysts are active for the reduction of all ketoesters with low to moderate enantioselectivities depend-
ing on the nature of the substrate and ligand. Interestingly, for several substrates both enantiomers of the
hydroxyesters have been obtained according either to the catalytic method or to the structure of the
ligand.
Dedicated to Professor Henri Kagan on the
occasion of his 80th birthday
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
widely employed for the preparation of chiral alcohols.6,7 In such
a context, we have investigated enzymatic resolution through li-
Chiral alcohols are widely used building blocks which have
numerous applications for the synthesis of pharmaceuticals and
agrochemicals. Nowadays, methodologies following the criteria of
green chemistry such as the use of safe reagents and solvents,
the recyclability of catalysts, and the easy separation of reaction
products are required for the preparation of chiral compounds.1
Both organometallic and biological enantioselective catalysts have
been developed as complementary tools for the reduction of ke-
tones. Asymmetric transfer hydrogenation (ATH) has many advan-
tages for the easy preparation of enantiomerically enriched
alcohols avoiding the use of hydrogen gas under high pressure.2
In recent years ATH reactions in water have focused increasing
interest.3 In this area we have studied catalysts for ATH reduction
of ketones in water and reported on ruthenium-based catalysts
which are reusable both with the same substrate or changing the
ketone for each reduction without a loss of enantioselectivity.4 Fur-
thermore a variety of ligands were compared in multi-substrate
one-pot reductions in order to optimize the catalyst.5 We selected
aminoindanol and a prolinamide ligand derived from aminoinda-
nol as the most enantioselective ligands for ruthenium-catalyzed
reductions of aromatic ketones in water.
pase-catalyzed acylation for the production of secondary chiral
alcohols and improved the selectivities of the reaction by the opti-
mization of various parameters such as the nature of substrates,
acylating agents, or additives.8
The comparison between enantioselective bio- and metal-cata-
lyzed reactions has rarely been examined.9 The bioreduction of ke-
tones using Daucus carota L. has been the focus of a recent review
and the results compared with those given by several chemical cat-
alysts. We thus decided to evaluate the ruthenium catalysts that
we have previously studied for the enantioselective reduction of
ketoesters in water in order to compare them with a biocatalyzed
reaction under similar conditions. Saccharomyces cerevisiae was se-
lected as a readily available, cheap enzymatic catalyst, widely used
for the preparation of chiral molecules for 20 years,10 and for the
enantioselective reduction of ketones as well as of ketoesters.11
2. Results and discussion
In order to compare both the activities and the enantioselectiv-
ities of S. cerevisiae as a biocatalyst and of ruthenium complexes for
the reduction of ketoesters in water, we selected a variety of sub-
Biocatalyses are alternative methods to perform reactions un-
der mild conditions with high enantioselectivities and have been
strates 1–13 including aliphatic and aromatic a-ketoesters, panto-
lactone, acyclic and cyclic b-ketoesters (see Table 1). The reaction
with S. cerevisiae was first optimized for the asymmetric reduction
of methyl benzoylformate 1. In a buffered aqueous solution (pH 7)
at 30 °C after 2 h a total conversion into the (R)-enantiomer of the
* Corresponding authors. Fax: +33 169157680.
E-mail addresses: jacqueline.collin@u-psud.fr (J. Collin), jean-claude.fiaud@
u-psud.fr (J.-C. Fiaud), lzouioueche@yahoo.fr (L.A. Zouioueche).
Fax: +33 169157680.
corresponding
a-hydroxyester was observed. Reduction was
highly enantioselective since the (S)-isomer was not detected
(Table 1, entry 1a). The above-mentioned conditions have been
à
Fax: +213 38 87 65 67.
0957-4166/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetasy.2010.05.014

1212
S. Zeror et al. / Tetrahedron: Asymmetry 21 (2010) 1211–1215
employed for the reduction of the other substrates by S. cerevisiae.
Reduction with ethyl benzoylformate 2 afforded similarly high
enantiomeric excess (>99%) (entry 2a) while the reduction of an
racemic b-hydroxyester (entry 9a). The reduction of cyclic b-keto-
esters 11–13 delivered the cis isomer selectively (entries 11a and
12a) or in a very large amount (entry 13a). High enantioselectivi-
ties have been observed for all of these substrates especially for
the reduction of b-ketoester 11 including a five-membered ring
(entry 11a, only enantiomer (R,S) could be detected). Substrates
1–8 could thus be reduced in good yields using S. cerevisiae but
asymmetric inductions were highly dependent upon the substrates
and low enantioselectivities were observed for substrates contain-
ing halogen atoms.
aliphatic a-ketoester and ketopantolactone was less enantioselec-
tive (entries 3a and 5a). The presence of a trifluoro group was
detrimental to the enantioselectivity since ethyl trifluoromethyl-
pyruvate afforded the racemic hydroxy ester (compare entries 3a
and 4a). The reduction of linear b-ketoesters 7, 8 catalyzed by S.
cerevisiae furnished products with enantiomeric excesses of over
80% (entries 7a and 8a) but the presence of chlorine led to a nearly
Table 1
Enantioselective reduction of ketoesters catalyzed by Saccharomyces cerevisiae or by ruthenium complexes
Entry
Substrate
Catalysta
t (h)
Yieldb (%)
cis/transc
Eed (%)
Confe
1a
1b
1c
S.C
2
4
48
40
80
69
71
65
>99f
77
5
(R)
(S)
(S)
(R)
O
L1
L2
L3
Ph
Ph
CO2Me
1d
13
1
2a
2b
2c
S.C
2
4
48
40
76
69
62
72
>99f
60
30
13
(R)
(S)
(S)
(R)
O
L1
L2
L3
CO2Et
2d
2
3a
3b
3c
S.C
4
4
24
24
68
78
76
74
93
10
11.5
11
(S)
(S)
(S)
(S)
O
L1
L2
L3
OEt
O
3d
O
3
4a
4b
4c
S.C
2
18
24
24
63
52
75
70
5
3
10
15
L1
F3C
L2
L3
OEt
4d
O
4
5a
5b
5c
S.C
2
2
2
60
82
79
61
69.5
66
35
77
(R)
(R)
(R)
(R)
O
L1
L2
L3
O
5d
40
O
5
6a
6b
6c
S.C
168
4
48
40
51
72
66
76
83
38
70
81
(S)
(R)
(R)
(S)
O
O
L1
L2
L3
Ph
O
OEt
6d
6
7a
7b
7c
S.C
24
16
40
74
80
71
64
91.5
20
15
3
(S)
(R)
(R)
(R)
O
L1
L2
L3
OMe
7d
168
7
8a
8b
8c
S.C
16
16
48
78
71
69
59
83
25
15
4
(S)
(R)
(R)
(R)
O
O
L1
L2
L3
OEt
O
8d
168
9a
9b
9c
S.C
2
4
20
72
73
68
61
62
9
5
30
3
(S)
(R)
O
L1
Cl
L2
L3
OEt
9d
9
10a
10b
10c
10d
S.C
16
16
72
24
72
81
68
79
90
17.5
4
29
(S)
(S)
(S)
(S)
O
O
L1
L2
L3
OEt
10
11a
11b
11c
11d
S.C
2
2
20
78
79
82
67
65
>99f
>99f
>99f
43
25
10
(R,S)
(S,R)
(S,R)
(S,R)
O
L1
L2
L3
>99f
96/4
CO2Me
11

S. Zeror et al. / Tetrahedron: Asymmetry 21 (2010) 1211–1215
1213
Table 1 (continued)
Entry
Substrate
Catalysta
t (h)
Yieldb (%)
cis/transc
Eed (%)
87
Confe
12a
12b
12c
12d
S.C
16
4
48
48
72
77
76
71
>99f
87/13
95/5
88/12
(R,S)
(S,R)
(S,R)
(S,R)
O
O
L1
59 (60)g
L2
L3
76 (50)g
17 (40)g
CO2Me
CO2Et
12
13a
13b
13c
13d
S.C
16
2
48
48
69
76
78
60
96/4
66/34
92/8
93/7
88 (99)g
57 (80)g
(R,S)
(S,R)
(S,R)
(S,R)
O
O
L1
L2
L3
70 (10)g
53 (59)g
13
a
Reactions were performed with 3 g baker’s yeast and 30 mL phosphate buffer pH 7 for 1 mmol substrate or with 2.5% [RuCl2(p-cymene)]2 and 5% ligand L in water at
30 °C, for total conversion.
b
Isolated yield.
cis/trans ratio determined by GC.
Ee determined by chiral GC or HPLC of the product or of the 1-naphthoyl ester of the product.
Absolute configuration of the major enantiomer was assigned by comparison with the literature.
Only one peak was observed.
Ee cis (ee trans).
c
d
e
f
g
During our previous studies we have found that a ruthenium
complex coordinated with N-phenyl prolinamide L1 was an enan-
tioselective catalyst for the reduction of aromatic ketones.4 Mul-
ti-substrate screening of ruthenium-catalyzed reactions led to
the selection of two ligands N-aminoindanol prolinamide L2 and
aminoindanol L3 which afforded high enantiomeric excesses for
different types of ketones.5 We have now investigated the asym-
asymmetric induction superior to that given by the biocatalyst.
Reduction of aromatic b-ketoester 6 with ruthenium complexes
gave the product 6a with moderate to good enantiomeric excesses
(38–81%) (entries 6b–6d). For this substrate aminoindanol L3 was
the most enantioselective ligand and gave the same major enantio-
mer in shorter reaction times than Saccharomyces cerevisae while
the opposite configuration predominated with other ligands.
The ruthenium-catalyzed reduction of aliphatic linear b-keto-
esters, 7–10, afforded low asymmetric inductions (ee <30%) in all
cases (entries 7b–7c, 8b–8c, 9b–9c, 10b–10c) with the three
ligands L1–L3. In the case of aliphatic linear b-ketoesters variations
in the size of ester group or in the length of the chain did not im-
prove the enantiomeric excess. As in the biocatalyzed reaction, a
ruthenium-catalyzed reduction of the cyclic b-ketoester 11 yielded
the cis isomer selectively (entries 11b–11d) or in very large
amounts (entries 12b–12d and 13b–13d). While b-hydroxyester
11a including a five-membered ring was obtained with low enan-
tiomeric excesses whatever ligand was employed, reduction of
substrates 12 and 13 was more selective. For b-hydroxyesters
12a and 13a the highest enantiomeric excess was recorded with
N-aminoindanol prolinamide L2 ligand (entries 12c and 13c), the
major configuration in this case (S, R) being opposite to that given
by S. cerevisae. No variation of asymmetric induction between the
reduction of methyl ester 12 and ethyl ester 13 was found with the
biocatalyst and ruthenium catalysts coordinated with L1 and L2
ligands. Surprisingly, an increase in enantiomeric excesses of the
two diastereoisomers of the ethyl b-hydroxyester 13a was
metric reduction of
a- and b-ketoesters using ruthenium com-
plexes coordinated with ligands L1–L3 (Scheme 1). The results are
gathered in Table 1. Reactions were performed using 5 mol % cata-
lyst and furnished total conversions into hydroxyesters using
a
- and b-ketoesters as substrates with reaction times depending
on the ligand. Reactions were faster with N-phenylprolinamide L1
than with N-aminoindanolprolinamide L2 and aminoindanol L3.
The linear benzoyl formic acid esters 1 and 2 were reduced with
good enantioselectivities using N-phenylprolinamide L1 while li-
gands L2 and L3 gave poor results (entries 1b–1d and 2b–2d). Inter-
estingly,
a-hydroxyesters 1a and 2a provided by ruthenium
complexes coordinated with L1 have an (S)-configuration while
the biocatalyst furnished the (R)-enantiomer (entries 1a and 1b,
2a and 2b). Unfortunately, the reduction of substrates 3 and 4 with
ruthenium catalysts led to the
meric excesses, whatever ligand was employed (entries 3b–3d,
4b–4d). The -hydroxyester 5a was isolated with enantiomeric ex-
a-hydroxyester with low enantio-
a
cesses from 35% to 77% using ruthenium complexes (entries 5b–
5d) with the same configuration (R) as that given by S. cerevisae.
The ligand aminoindanol L3 was the most enantioselective with
O
O
OH
O
cat*
cat* : Saccharomyces Cerevisiae
R2
R2
or 2.5% [RuCl2(p-cymene)]2, 5% L
º
R1
n = 0,1
O
R1
O
H2O, 30 C
n
n
1a-13a
1-13
HO
HO
O
O
H2N
N
H
N
H
NH
NH
L1
L2
L3
Scheme 1.

1214
S. Zeror et al. / Tetrahedron: Asymmetry 21 (2010) 1211–1215
observed compared to the methyl ester 12a for reactions involving
aminoindanol L3.
4.2. General procedure for catalytic reactions
As a general trend the reduction of the various
a
- and b-ketoest-
In a Schlenk tube, a solution of [RuCl2(p-cymene)]2 (15.5 mg,
0.025 mmol) and ligand (0.05 mmol) in 4 mL of water was stirred
at 30 °C for 1 h. Sodium formate (0.68 g, 10 mmol) and substrate
(1 mmol) were then added and the solution was maintained at
30 °C until total reduction of the ketone, as monitored by TLC
(reaction times reported in Table 1). Organic products were then
extracted with hexane (2 ꢀ 8 mL) and dried over MgSO4. After con-
centration, the product was purified by thin layer chromatography
with hexane/ethyl acetate mixtures and spectral data compared
with the literature.
ers catalyzed by S. cerevisae gave higher enantiomeric excesses than
ruthenium complexes except for ketopantolactone 5 which was re-
duced with similar enantioselectivities with both types of catalysts.
However, ruthenium complexes afforded interesting asymmetric
inductions (>70% ee) in some cases, such as aromatic
1 and 2, pantolactone 5, aromatic b-ketoester 6, and cyclic b-ketoest-
ers 12 and 13. As expected reductions of aromatic - and b-ketoest-
a-ketoesters
a
ers were more enantioselective than the corresponding aliphatic
molecules. Different ligands gave the best results according to the
structure of the substrate, phenyl prolinamide L1 for aromatic
a-
ketoesters 1 and 2, ligand L2 for cyclic b-ketoesters 12 and 13, and
aminoindanol L3 for ketopantolactone 5 and aromatic b-ketoester
6. The presence of a trifluoromethyl group or a chlorine atom was
detrimental to the enantioselectivity with both types of catalysts.
Interestingly, for several substrates both enantiomers could be
obtained using either S. cerevisae or ruthenium complex (aromatic
4.3. General procedure for biocatalytic reactions
A suspension of baker’s yeast (3 g) in buffer solution (pH 7)
(30 mL) was maintained at 30 °C for 15 min. Then, the substrate
(1 mmol) was gradually added and the mixture vigorously stirred
at 30 °C. Progress of the reduction was monitored by TLC (reaction
times reported in Table 1). The reaction mixture was extracted sev-
eral times with CH2Cl2. After drying over anhydrous MgSO4 the sol-
vent was evaporated under reduced pressure.
a
- and b-ketoesters 1 and 2 and cyclic b-ketoesters 11–13). In the
case of b-ketoester 6 using N-aminoindanol prolinamide L2 and
aminoindanol L3 as ligands furnished, respectively, (R) and (S) as ma-
jor enantiomers with good enantiomeric excesses.
4.3.1. (R)-Methyl-2-hydroxy-2-phenylacetate 1a
HPLC (Chiralcel OD-H, hexane/i-PrOH: 90/10, 1.0 mL/min,
3. Conclusion
k = 254 nm): tS = 7.57 min, tR = 13.07 min.
½
a 2D0
ꢁ
¼ ꢂ134 (c 1.0,
MeOH) for 99% ee, Lit [
a]
D = ꢂ143 (c 1.0, MeOH).14
This comparison between enantioselective biocatalyzed and
ruthenium-catalyzed reduction of ketoesters in water reveals sev-
eral interesting characteristics. For several families of substrates
good asymmetric inductions have been obtained as well as being
enantiocomplementarity with biocatalysts.12 Since the enantio-
meric excesses are dependent on the substrates and ligands, the
optimization of the catalyst could be envisaged for the different
4.3.2. (R)-Ethyl-2-hydroxy-2-phenylacetate 2a
HPLC (Chiralcel OD-H, hexane/i-PrOH: 90/10, flow 1.0 mL/min,
k = 254 nm): tS = 6.4 min, tR = 11.2 min. ½a D20
¼ ꢂ132 (c 0.9, CHCl3)
ꢁ
for 99% ee, Lit [
a]
D = ꢂ134 (c 1.0, MeOH, ee = 90%).14
families of a- and b-ketoesters. The work-up is very simple for both
4.3.3. (S)-Ethyl 2-hydroxypropanoate 3a
procedures with an easy separation of the product from the cata-
lyst. Since ligands are provided by the chiral pool and ruthenium
catalysts can be recycled,4 aryl ketoesters and cyclic b-ketoesters
reductions afford products with complementary configurations
using inexpensive chiral sources. Although until now S. cerevisae
furnishes higher asymmetric inductions than ruthenium catalysts
in most cases, the possibility of working on a larger scale with
the latter should lead to their development for interesting applica-
tions in the future.
Enantiomers of 3a could not be separated by chiral HPLC or GC.
After reaction the reduction products were transformed in naph-
thoyl esters. To a solution of alcohol 3a (1 mmol) in CH2Cl2 were
added a few mg DMAP, triethylamine (10 mg, 1 mmol), naphthoyl
chloride (190 mg, 1 mmol). After stirring overnight, the solution
was extracted with CH2Cl2, and after drying over MgSO4, the sol-
vent was evaporated under reduced pressure. The product was
purified by thin layer chromatography with hexane/ethyl acetate
mixture (70/30).
4.3.4. 1-(Ethoxycarbonyl)ethyl 2-naphthoate
HPLC (Chiralcel OD-H, hexane/i-PrOH: 95/5, flow 0.5 mL/min,
k = 254 nm): t1 = 14.10 min, t2 = 19.32 min.
4. Experimental
4.1. General
Ligands L1 and L2 were synthesized according to the literature
procedures.13 Ligand L3 and catalyst precursor [RuCl2(p-cymene)]2
and substrates were commercially available. Saccharomyces C type
II was purchased from SIGMA.
4.3.5. Ethyl 3,3,3-trifluoro-2-hydroxypropanoate 4a
After reaction product 4a was transformed in a naphthoyl ester
and purified as described above.
4.3.6. 1-(Ethoxycarbonyl)-2,2,2-trifluoroethyl 1-naphthoate
HPLC (Chiralcel OD-H, hexane/i-PrOH: 98/2, flow 0.5 mL/min,
k = 254 nm): t1 = 11.08 min, t2 = 13.67 min.
Bruker AM 250 and AM 360 spectrometers, operating at 250
and 360 MHz for 1H, and at 62.5 and 90.6 MHz for 13C, were used
for the NMR spectra. Optical rotations were determined using a
Perkin–Elmer 241 Polarimeter at room temperature using a cell
of 1 dm length and k = 589 nm. HPLC analyses were performed
on a Thermo Separation Product Pompe P100 with a UV detector
and a chiral stationary-phase column Chiralcel OD-H. GC analyses
were performed on Fisons 9000 apparatus equipped with a Chiral-
dex b-PM column (50 m ꢀ 0.25 mm) or a Supelco b-Dex 225 col-
umn and hydrogen as carrier gas (1.0 mL/min). All of the crude
products were purified by preparative thin layer chromatography
on Silica Gel 60 PF254 (heptane/ethyl acetate 50/50).
4.3.7. (R)-Dihydro-3-hydroxy-4,4-dimethylfuran-2(3H)-one 5a
GC (ChiralDex b-PM, T (°C) column = 110 °C): tS = 56.8 min,
tR = 62.4 min.
4.3.8. (S)-Ethyl 3-hydroxy-3-phenylpropionate 6a
HPLC (Chiralcel OD-H, hexane/i-PrOH: 90/10, flow 0.5 mL/min,
k = 254 nm): tS = 15.1 min, tR = 20.9 min.
½
a 2D0
ꢁ
¼ ꢂ35:2 (c, 0.5,
CHCl3) for 83% ee, Lit [
a
]
D = +43.7 (c 1.4, CHCl3)].15

S. Zeror et al. / Tetrahedron: Asymmetry 21 (2010) 1211–1215
1215
Tetrahedron: Asymmetry 1999, 10, 2045–2061; (d) Gladiali, S.; Alberico, E. Chem.
Rev. 2006, 226–236; (e) Samee, J. S. M.; Bäckvall, J. S. M.; Andersson, P. G.;
Brandt, P. Chem. Rev. 2006, 237–248; (f) Ikariya, T.; Murata, K.; Noyori, R. Org.
Biomol. Chem. 2006, 4, 393–406.
4.3.9. (S)-Methyl-3-hydroxybutanoate 7a
Reaction product 7a was transformed into naphthoyl ester and
purified as described above.
3. (a) Rhyoo, H. Y.; Park, H.-J.; Cheng, Y. Y. Chem. Commun. 2001, 2064–2065; (b)
Ma, Y.; Liu, H.; Chen, L.; Cui, X.; Zhu, J.; Deng, J. Org. Lett. 2003, 5, 2103–2106;
(c) Wu, X.; Li, X.; Hems, W.; King, F.; Xiao, J. Org. Biomol. Chem. 2004, 2, 1818–
1821; (d) Li, X.; Wu, X.; Chen, W.; Hancock, F. E.; King, F.; Xiao, J. Org. Lett. 2004,
6, 3321–3324; (e) Bubert, C.; Blacker, J.; Brown, S. M.; Crosby, J.; Fitzjohn, S.;
Muxworthy, J. P.; Thorpe, T.; Williams, J. M. J. Tetrahedron Lett. 2001, 42, 4037–
4039; (f) Wu, X.; Li, X.; King, F.; Xiao, J. Angew. Chem., Int. Ed. 2005, 44, 3407–
3411; (g) Li, X.; Blacker, J.; Houson, I.; Wu, X.; Xiao, J. Synlett 2006, 1155–1160;
(h) Cortez, N. A.; Aguirre, G.; Parra-hake, M.; Somanathan, R. Tetrahedron Lett.
2007, 48, 4335–4338; (i) Wu, X.; Li, X.; McConville, M.; Saidi, O.; Xiao, J. J. Mol.
Catal. A 2006, 247, 153–158; (j) Matharu, D. S.; Morris, D. J.; Clarkson, G. J.;
Wills, M. Chem. Commun. 2006, 3232–3234; (k) Wu, X.; Xiao, J. Chem. Commun.
2007, 2449–2466; (l) Wu, X.; Li, X.; Zanotti-Gerosa, A.; Pettman, A.; Liu, J.;
Mills, A. J.; Xiao, J. Chem. Eur. J. 2008, 14, 2209–2222; (m) Mao, J.; Wan, B.; Wu,
F.; Lu, S. Tetrahedron Lett. 2005, 46, 7341–7344.
4.3.10. 1-(Methoxycarbonyl)propan-2-yl 1-naphthoate
HPLC (Chiralcel OD-H, hexane/i-PrOH: 90/10, flow 0.5 mL/min,
k = 254 nm): t1 = 14.8 min, t2 = 15.77 min.
4.3.11. (S)-Ethyl 3-hydroxybutanoate 8a
Reaction product 8a was transformed into naphthoyl ester and
purified as described above.
4.3.12. 1-(Ethoxycarbonyl)propan-2-yl 1-naphthoate
HPLC (Chiralcel OD-H, hexane/i-PrOH: 90/10, flow 0.5 mL/min,
k = 254 nm): t1 = 14.0 min, t2 = 15.3 min.
4. Zeror, S.; Collin, J.; Fiaud, J.-C.; Aribi-Zouioueche, L. J. Mol. Catal. A 2006, 256,
85–89.
5. Zeror, S.; Collin, J.; Fiaud, J.-C.; Aribi-Zouioueche, L. Adv. Synth. Catal. 2008, 350,
197–204.
4.3.13. (S)-Ethyl 4-chloro-3-hydroxybutanoate 9a
Reaction product 9a was transformed in naphthoyl ester and
purified as described above.
6. (a) Wong, C.-H.; Whitesides, G. M. In Enzymes in Synthetic Organic Chemistry;
Pergamon Press: Oxford, 1994; (b) Drauz, K.; Waldman, H.. In Enzyme Catalysis
in Organic Synthesis; VCH: New York, 1995; Vols. I, II, and III, (c) Patel, R. In
Stereoselective Biocatalysis; Marcel Dekker: New York, 2000; (d) Desantis, G. In
Modern Drug Discovery; American Chemical Society, 2002; pp 43–47; (e) Faber,
K. In Biotransformations in Organic Chemistry, 5th ed.; Springer: Berlin, 2004; (f)
Klibanov, A. M. J. Am. Chem. Soc. 1986, 108, 2767–2768; (g) Goldberg, K.;
Schroer, ; Lütz, S.; Liese, A. Appl. Microbiol. Biotechnol. 2007, 76, 249–255.
7. (a) Nakamura, K.; Yamanaka, R.; Matsuda, T.; Harada, T. Tetrahedron:
Asymmetry 2003, 14, 2348–2353; (b) Borges, K. B.; de Souza Borges, W.;
Duran-Patron, R.; Tallarico Pupo, M.; Bonato, P. S.; Gonzalez Collado, I. G.
Tetrahedron: Asymmetry 2009, 20, 385–397; (c) Lacherezt, R.; Gomez Pardo, D.;
Cossy, J. Org. Lett. 2009, 11, 1245–1248; (d) Yadav, J. S.; Nanda, S.; Reddy, P. T.;
Rao, A. B. J. Org. Chem. 2002, 67, 3900–3903; (e) Podea, P. V.; Paizc, C.; Tosa, M.
I.; Irimie, F. D. Tetrahedron: Asymmetry 2008, 19, 1959–1964; (f) He, C.; Chang,
D.; Zhang, J. Tetrahedron: Asymmetry 2008, 19, 1347–1351.
8. (a) Aribi-Zouioueche, L.; Fiaud, J. C. Tetrahedron Lett. 2000, 41, 4085–4088; (b)
Bouzemi, N.; Debbeche, H.; Aribi-Zouioueche, L.; Fiaud, J. C. Tetrahedron Lett.
2004, 45, 627–630; (c) Bouzemi, N.; Aribi-Zouioueche, L.; Fiaud, J. C.
Tetrahedron: Asymmetry 2006, 17, 797–800; (d) Merabet, M.; Melaïs, N.;
Boukachabia, M.; Fiaud, J. C.; Aribi-Zouioueche, L. J. Soc. Alger. Chim. 2007, 17,
185–194; (e) Merabet-Khelassi, M.; Aribi-Zouioueche, L.; Riant, O. Tetrahedron:
Asymmetry 2008, 19, 2378–2384.
9. (a) Blanchard, N.; Van de Weghe, P. Org. Biomol. Chem. 2006, 4, 2348–2353; (b)
Hage, A.; Petra, D. G. I.; Field, J. A.; Schipper, D.; Wijnberg, J. B. P. A.; Kamer, P. C.
J.; Reek, J. N. H.; van Leeuwen, P. W. N. M.; Wever, R.; Schoemaker, H. E.
Tetrahedron: Asymmetry 2001, 12, 1025–1034.
10. (a) Servi, S. Synthesis 1990, 1–25; (b) Csuk, R.; Glanzer, B. I. Chem. Rev. 1991, 91,
49–97; (c) Santaniello, E.; Ferraboschi, P.; Grisenti, P.; Manzocchi, A. Chem. Rev.
1992, 92, 1071–1140.
11. (a) Nakamura, K.; Kondo, S.; Nakajima, N.; Ohno, A. Tetrahedron 1995, 51, 687–
694; (b) Engelking, H.; Pfaller, R.; Wich, G.; Weuster-Botz, D. Enzyme Microb.
Technol. 2006, 38, 536–544; (c) Yang, G.; Ou, Z.; Yao, S.; Xu, J. J. Mol. Catal. B
2009, 57, 83–88; (d) Shieh, W.; Gopalan, A. S.; Sih, C. J. J. Am. Chem. Soc. 1985,
107, 2993–2994; (e) Gopalan, A. S.; VanMiddlesworth, F.; Shieh, W.; Sih, C. J. J.
Am. Chem. Soc. 1983, 105, 5925–5926; (f) Perrone, M. G.; Santandrea, E.;
Scilimati, A.; Tortorella, V.; Capitelli, F.; Bertolasi, V. Tetrahedron: Asymmetry
2004, 15, 3501–3510; (g) Abalain, C.; Buisson, D.; Azerad, R. Tetrahedron:
Asymmetry 1996, 7, 2983–2996.
4.3.14. 1-(Ethoxycarbonyl)-3-chloropropan-2-yl 1-naphtoate
HPLC (Chiralcel OD-H, hexane/i-PrOH: 90/10, flow 0.5 mL/min,
k = 254 nm): t1 = 13.3 min, t2 = 14.7 min.
4.3.15. (S)-Ethyl 3-hydroxyhexanoate 10a
Reaction product 10a was transformed in naphthoyl ester and
purified as described above.
4.3.16. 1-(Ethoxycarbonyl)pentan-2-yl 2-naphthoate
HPLC (Chiralcel OD-H, hexane/i-PrOH: 99/1, flow 0.5 mL/min,
k = 254 nm): t1 = 24.22 min, t2 = 26.88 min.
4.3.17. (R,S)-Methyl-2-hydroxycyclopentanecarboxylate 11a
GC (Supelco b-Dex225, (T column = 110 °C)): d1 (t1 = 21.8 min,
t2 = 22.6 min), d2 (t1 = 25.6 min, t2 = 26.6 min).
½
a 2D0
ꢁ
¼ þ15 (c,
1.95, CHCl3) for 99% ee, Lit [
a
]
D = +15.8 (c, 3.5, CHCl3)].16
4.3.18. (R,S)-Methyl-2-hydroxycyclohexanecarboxylate 12a
HPLC (Chiralcel OD-H, hexane/i-PrOH: 99/1, flow 0.5 mL/min,
k = 215 nm): d1 (t1 = 23.03 min, t2 = 28.42 min), d2 (t1 = 39.15 min,
t2 = 49.47 min).
4.3.19. (R,S)-Ethyl-2-hydroxycyclohexanecarboxylate 13a
HPLC (Chiralcel OD-H, min hexane/i-PrOH: 95/5, flow 0.5 mL/
min, k = 215 nm): d1 (t1 = 10.4 min, t2 = 11.3 min), d2 (t1 = 12.5
min, t2 = 13.65).
References
12. Chen, Y.; Xu, J.; Xia, Y.; Lin, H.; Xia, S.; Wang, L. Tetrahedron: Asymmetry 2007,
18, 2537–2540.
13. (a) Ryoo, H. Y.; Yoon, Y. A.; Park, H. J.; Chung, Y. K. Tetrahedron Lett. 2001, 42,
5045–5048; (b) Almasi, D.; Alonso, D. A.; Najera, C. Tetrahedron: Asymmetry
2006, 17, 2064–2068.
14. Chadha, A.; Baskar, B. Tetrahedron: Asymmetry 2002, 13, 1461–1464.
15. Xu, C.; Yuan, C. Tetrahedron 2005, 61, 2169–2186.
1. (a) Anastas, P. T.; Warner, J. C. Green chemistry: Theory and Practice; Oxford
University Press: New York, 2000; (b) Trost, B. M. Science 1991, 1471–1477;
Angew. Chem., Int. Ed. 1995, 107, 285–307; (c) Trost, B. M. Angew. Chem., Int. Ed.
1995, 34, 259–281; (d) Sheldon, R. A. Chem. Ind. 1992, 903.
2. (a) Noyori, R.; Hashiguchi, S. Acc. Chem. Res. 1997, 30, 97–102; (b) Noyori, R.;
Ohkuma, T. Angew. Chem., Int. Ed. 2001, 40, 40–73; (c) Palmer, M. J.; Wills, M.
16. Sato, T.; Maeno, H.; Noro, T.; Fujisawa, T. Chem. Lett. 1988, 1739–1742.