Practical two-step synthesis of an enantiopure aliphatic terminal (S)-epoxide based on reduction of haloalkanones with "designer cells"

Article abstract of DOI:10.1002/adsc.200700244

A practical biocatalytic method for the synthesis of aliphatic β-halogenated (S)-alcohols as epoxide precursors by means of an enantioselective reduction of the corresponding ketones with recombinant whole cells, bearing an alcohol dehydrogenase and a glucose dehydrogenase, was developed. The biotransformations operate at high substrate concentrations of up to 208 g/L, and afford the (S)-β-halohydrins with both high conversions of >95% and enantioselectivities of >99% ee. Base-induced cyclization of the β-halohydrin intermediates gave the desired (S)-epoxides in high yield and enantiomeric purity (>99% ee).

Full text of DOI:10.1002/adsc.200700244

UPDATES
DOI: 10.1002/adsc.200700244
Practical Two-Step Synthesis of an Enantiopure Aliphatic
Terminal (S)-Epoxide Based on Reduction of Haloalkanones
with “Designer Cells”
a,
b
b
a
Albrecht Berkessel, * Claudia Rollmann, Francoise Chamouleau, Stefanie Labs,
b
b,c,
Oliver May, and Harald Grçger *
Institute of Organic Chemistry, University of Cologne, Greinstraße 4, 50939 Cologne, Germany
a
Fax : (+49)-221-470-5102; e-mail: berkessel@uni-koeln.de
Degussa AG, Service Center Biocatalysis, P.O. Box 1345, 63403 Hanau, Germany
Current address: University of Erlangen-Nuremberg, Institute of Organic Chemistry, Henkestr. 42, 91054 Erlangen,
b
c
Germany
Fax: (49)-9131-85-21165; e-mail: harald.groeger@chemie.uni-erlangen.de
Received: May 18, 2007; Published online: November 21, 2007
Supporting information for this article is available on the WWW under http://asc.wiley-vch.de/home/.
Abstract: A practical biocatalytic method for the
synthesis of aliphatic b-halogenated (S)-alcohols as
epoxide precursors by means of an enantioselective
reduction of the corresponding ketones with re-
combinant whole cells, bearing an alcohol dehydro-
genase and a glucose dehydrogenase, was devel-
oped. The biotransformations operate at high sub-
strate concentrations of up to 208 g/L, and afford
the (S)-b-halohydrins with both high conversions of
combination with pyridine N-oxides as oxidant gave
[5a]
1-octene oxide with 6% conversion and 28% ee.
Application of the Shi catalyst to vinylcyclohexane
[5b]
gave the epoxide in high yield and with 71% ee.
Recently, significant advances were achieved in this
area. Strukul et al. reported the asymmetric epoxida-
tion of terminal alkenes with H O catalyzed by pen-
2
2
tafluorophenyl-Pt(II) complexes, with 1-octene oxide
[
5c]
being formed in 88% yield and 79% ee. Katsuki
et al. developed a Ti-based salen catalyst and reported
70% yield and 82% ee in the epoxidation of 1-octene
>
95% and enantioselectivities of >99% ee. Base-
induced cyclization of the b-halohydrin intermedi-
ates gave the desired (S)-epoxides in high yield and
enantiomeric purity (>99% ee).
[
5d,e]
with H O as oxidant.
Chemocatalytic kinetic reso-
2
2
lution turned out to work efficiently when using
short-chain aliphatic epoxides such as propylene
oxide, but is limited by a maximum conversion of
Keywords: alcohols; asymmetric catalysis; enzyme
catalysis; epoxides; halohydrins; reduction
[
6]
5
0%. High enantioselectivity of >99% ee was re-
ported for the microbial epoxidation of hexadec-1-
ene, but in combination with both low substrate con-
[
7]
centration [ꢀ5% (v/v)] and yield (41%). Arnold
et al. applied an engineered cytochrome P450 BM-3
enzyme to the epoxidation of several terminal aliphat-
ic alkenes and achieved enantioselectivities between
Introduction
[
8]
Enantiomerically pure terminal (S)-epoxides are im- 55 and 83% ee. In general, enantioselectivity in en-
portant chiral building blocks, widely used, e.g., as in- zymatic epoxidation depends on the chain length and
[
1]
[9]
termediates in the synthesis of pharmaceuticals.
varies widely between 60 and >99% ee. Further-
Whereas numerous asymmetric transformations com- more, resolution using epoxide hydrolases is known
[
2]
[3]
[10]
prising chemocatalytic and biocatalytic techniques for styrene oxides and aliphatic epoxides. Neverthe-
have been developed for the enantioselective synthe- less, terminal straight-chain aliphatic epoxides remain
sis of aromatic terminal epoxides, there is still compa- difficult substrates, in particular with respect to enan-
ratively little methodology available for the prepara- tioselectivity. Very recently, Kroutil et al. reported an
tion of enantiomerically pure aliphatic terminal epox- elegant chemoenzymatic approach for optically active
ides. In contrast to, e.g., allylic alcohols or conjugated terminal epoxides based on the asymmetric synthesis
cis-alkenes, the enantioselective epoxidation of termi- of b-halohydrins from a-haloketones using alcohol de-
[
4]
[11,12]
nal aliphatic alkenes still is a challenging task. In hydrogenases (ADH) and subsequent cyclization.
early work, chiral ruthenium-porphyrin complexes in The ADH-catalyzed reduction of 1-chloro-2-octanone
Adv. Synth. Catal. 2007, 349, 2697 – 2704
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2697

Albrecht Berkessel et al.
UPDATES
1
a was combined with a cofactor-regeneration of combinant whole-cell biocatalyst. In order to prepare
[11]
NADH using 2-propanol. Typically, the reductions the (S)-b-halohydrins (S)-2, we used our recently de-
were carried out at substrate concentrations of 8–18 g/L veloped whole-cell catalyst, overexpressing an (R)-al-
and gave good results for the (R)-alcohol (ADH from cohol dehydrogenase from L. kefir (LK-ADH) and
Rhodococcus ruber) with a conversion of >99% and glucose dehydrogenase from T. acidophilum (TA-
[
14]
>
99% ee. In contrast, the (S)-1-chloro-2-octanol [(S)- GDH). The latter enzyme is needed for the in situ-
a] (ADH from Pseudomonas fluorescens) was regeneration of the cofactor NADPH via consump-
formed with low enantioselectivity (52% ee), and the tion of glucose under formation of gluconolactone,
2
[
11]
conversion did not exceed 63%. A subsequent pub- whereas the ADH catalyzes the reduction of 1 with
lication by Kroutil et al. describes the two-stage bio- consumption of the cofactor NADPH.
catalytic synthesis of highly enantiopure (S)-1-octene
oxide, albeit at chemical yields of only 34% for each
[13]
of the two steps.
In continuation of our studies on the use of tailor-
made whole-cell biocatalysts for the preparation of En route to the most challenging target (S)-1-octene
Results and Discussion
[
14,15]
optically active alcohols,
in the following we oxide, 1-bromo-2-octanone (1b) and 1-chloro-2-octa-
report a practical and efficient process for the highly none (1a) were needed as substrates. Ketone 1b can
enantioselective synthesis of aliphatic (S)-halohydrins, be prepared in 42% yield by a two-step/one-pot pro-
[
16]
running at high substrate concentrations of >100 g/L. cedure from 1-octene.
The latter method involves
The cofactor is regenerated by means of an enzyme- the use of over-stoichiometric amounts of NBS and
coupled approach. The products (S)-2 were subse- Cr(VI) oxide. We therefore developed a practical syn-
quently converted to the corresponding epoxide. The thesis of 1-chloro-2-octanone (1a) which avoids the
concept for the synthesis of the b-halohydrins is use stoichiometric use of toxic metals. As shown in
shown in Scheme 1 and is based on the use of a re- Scheme 2 (top), 1-chloro-2-octanone (1a) can be pre-
pared from 1-octene in 83% yield by a two-step pro-
cedure, using trichloroisocyanuric acid and TEMPO
(
catalytic amount). Alternatively, a two-step/one-pot
procedure using trichloroisocyanuric acid and RuCl3
catalytic amount) under phase-transfer conditions re-
(
sulted in 55% yield for the haloketone 1a (Scheme 2,
bottom).
Initial screening reactions on 1-bromo-2-octanone
(
1b) revealed a high activity of the biocatalyst har-
bouring the (R)-ADH. A subsequent transformation
on a preparative scale was done using a substrate con-
centration of 0.5M, corresponding to 104 g/L. We
were pleased to find that the biocatalytic reduction
gave the desired b-halohydrin (S)-2b with high con-
version (>95%) and excellent enantioselectivity
Scheme 1. Concept for an enzymatic reduction of a-halogen- (>99% ee; Table 1, entry 1). After extraction and iso-
ated ketones with recombinant whole-cell catalysts in bipha-
sic media.
lation, the yield of (S)-2b was 76%. The purity of this
material was sufficient for further conversion.
Scheme 2. Synthesis of 1-chloro-2-octanone (1a).
2698
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ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2007, 349, 2697 – 2704

Two-Step Synthesis of an Enantiopure Aliphatic Terminal (S)-Epoxide
UPDATES
Table 1. Asymmetric biocatalytic reduction of 1-halogenated
-octanones 1a, b using a recombinant whole-cell catalyst.
The analogous chloro ketone 1a can serve as sub-
strate as well. The reduction of 1a affords >95% con-
2
[
17-19]
version and >99% ee
4 h, at a biocatalyst loading of ~53 g/L of wet bio-
mass, and using a substrate concentration of 1.0M
corresponding to 162 g/L). In general, the yields of
after a reaction time of
2
(
isolated crude product, containing the desired product
in good purity sufficient for further transformations,
were high with, e.g., 82% and 88% for the biotrans-
formations at a substrate concentration of 1.0M
(
Table 1, entries 3 and 4).
Recently Kroutil et al. described the subsequent
and quantitative cyclization of the halohydrin (R)-2a
to the epoxide (R)-3, effected by the addition of
[a]
Entry Product Substrate input
Conversion
[%]
ee
[%]
À1
[b]
[gL ]
1
8.6 equivs. of powdered KOH during the biocatalytic
1
2
3
4
(S)-2b 104
(S)-2b 152
(S)-2b 208
(S)-2a 162
>95
>95
>95
>95
>99
>99
>99
>99
[
11]
reduction of 1a.
In analogy to this protocol, the
subsequent cyclization to (S)-1-octene oxide [(S)-3]
was carried out for the isolated b-halohydrins (S)-2a
and (S)-2b, with 10.0 equivs. of powdered NaOH in
diethyl ether (Scheme 3). Within one hour, quantita-
tive conversion of the halohydrins occurred, and the
desired epoxide (S)-3 was obtained in 92% yield in
both cases. The expected absolute configuration of
[
[
a]
For the general procedure, see Experimental Section.
The enantiomeric excess (ee) was determined by chiral
GC chromatography.
b]
As a next step, process development was carried the resulting epoxide [(À)-S] was confirmed by com-
out, in particular with respect to an increase of volu- parison of the measured optical rotation with the lit-
[
19]
metric productivity. Notably, increase of the substrate erature value.
concentration did not have a negative impact on the As recently described by Kroutil and co-workers,
reaction course. Thus, carrying out the whole-cell cat- the isolation of the intermediate b-halohydrin (S)-2a
[11]
alyzed reduction reactions at a substrate concentra- can be avoided in an alternative one-pot process.
tion of 0.75M and 1.0M (corresponding to a substrate We studied this concept using the recombinant whole-
input of 156 and 208 g/L, respectively) gave high con- cell biocatalyst E. coli DSM14459, overexpressing an
versions of >95% and enantioselectivities of >99% (R)-ADH from L. kefir and a GDH from T. acidophi-
ee in both cases (Table 1, entries 2 and 3).
lum (Scheme 4). After formation of the b-halohydrin
S)-2b with high conversion, subsequent adjustment
(
of the pH to 11 and stirring of the reaction mixture
for 2 h, followed by an extractive work-up led to the
desired epoxide (S)-3. In spite of a rapid cyclization
and formation of the epoxide (S)-3 with a high con-
version of >95%, extractive isolation of the product
under these conditions gave a yield of only 37% for
the crude epoxide. Potential reasons for this low yield
Scheme 3. Cyclization of the isolated b-halohydrins (S)-2a might be a lower efficiency of the extraction at high
and (S)-2b to (S)-1-octene oxide (S)-3.
pH compared to the analogous work-up at low pH.
Scheme 4. Two step-one pot synthesis of the epoxide (S)-3.
Adv. Synth. Catal. 2007, 349, 2697 – 2704
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
2699

Albrecht Berkessel et al.
UPDATES
Scheme 5. Gram-scale synthesis.
Further process development revealed that the syn- versions of >95% and enantioselectivities of >99%
thesis of the epoxide (S)-3 by means of two separated ee. Subsequent cyclization of the b-halohydrins gave
processes (reduction, epoxide cyclization) according the corresponding (S)-epoxide. The two-step process
to Scheme 5 is the method of choice. The efficiency of with isolation of the b-halohydrin intermediate turned
this two-step process was demonstrated in a multi- out to be superior to the one-pot process for the
gram scale synthesis. The b-bromohydrin (S)-2b was direct preparation of (S)-octene oxide, (S)-3, when
prepared under optimized reaction conditions (ac- using recombinant whole-cells as a catalyst. Extension
cording to Table 1, entry 3) at a substrate concentra- of the reaction scope towards the synthesis of other
tion of 1.0M, corresponding to 208 g/L. The biocata- types of aliphatic and enantiomerically pure terminal
lyst loading of the whole-cell catalyst of type E. coli epoxides is planned.
DSM14459, overexpressing the (R)-alcohol dehydro-
genase from L. kefir and glucose dehydrogenase from
T. acidophilum, was ~53 g of wet biomass/L. After a Experimental Section
reaction time of 25 h, a conversion of>95% and an
enantioselectivity of >99% ee was obtained Materials
(
8
Scheme 5). The b-halohydrin (S)-2b was isolated in
5% yield (crude product). The conversion of (S)-2b
1
-Octene, RuCl ·XH O and TEMPO were purchased from
3 2
Aldrich, Bu NBr from Fluka, trichloroisocyanuric acid and
NBS from Acros Organics, CrO from Janssen Chimica. All
chemicals were used without further purification. Solvents
4
to the epoxide (S)-3 was done in a subsequent step.
The b-halohydrin (S)-2b was cyclized, as described
3
above, with 10.0 equivs. of powdered NaOH in diethyl were distilled using standard techniques. Chromatographic
ether. The desired epoxide (S)-3 resulted after 1.0 h separations were performed using silica gel 60 (0.040–
in 92% yield (quantitative conversion) and with 0.063 mm/230–400 mesh ASTM) from Merck KGaA. For
the preparation of the whole-cell catalyst of type E. coli
>
99% ee.
DSM14459 [overexpressing the (R)-alcohol dehydrogenase
from L. kefir and glucose dehydrogenase from T. acidophi-
lum], see ref.
[14]
Conclusions
In conclusion, a practical biocatalytic method for the Instrumentation
synthesis of aliphatic terminal (S)-b-halohydrins by
means of an enantioselective reduction of the corre-
sponding ketones has been developed, which is based
on the use of a recombinant, ADH-containing whole-
cell catalyst. The biotransformations operate at a high
1
13
Nuclear magnetic resonance ( H and C) spectra were re-
corded on a Bruker Avance DPX300 (300 MHz) NMR spec-
trometer. Chemical shifts for protons and carbon atoms are
reported in parts per million (ppm) downfield from tetrame-
thylsilane and are referenced to residual protons in the
substrate input of up to 208 g/L and lead to the for- NMR solvent and carbon resonances of the solvent, respec-
mation of the desired (S)-alcohols with both high con- tively. FT-IR spectra were recorded on a Perkin–Elmer Par-
2700
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ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2007, 349, 2697 – 2704

Two-Step Synthesis of an Enantiopure Aliphatic Terminal (S)-Epoxide
UPDATES
agon 1000 FT-IR spectrometer with the ATR technique.
Data are reported as: wave number of absorption (cm ), in-
tensity of absorption (s=strong, m=medium, w=weak).
GC analyses were performed using a HP 6890 Series instru-
ment with a chiral stationary phase WCOT-FS CP-Chirasil-
Dex CB: Octakis-(2,6-di-O-pentyl-3-O-butyryl)-g-cyclodex-
0.01 equiv.) dissolved in 2.00 mL water and again trichloro-
isocyanuric acid (4.65 g, 20.0 mmol, 1.00 equiv.) dissolved in
20.0 mL acetone were added slowly. The pH value was kept
at 5 by adding a K CO solution (3.00M) during the reac-
tion. The mixture was stirred at room temperature for 1.0 h.
100 mL 2-propanol were added and the mixture was stirred
again for 30.0 min. The mixture was filtered and the solvent
was evaporated from the filtrate. The aqueous residue was
extracted 3 times with 50.0 mL ethyl acetate. The combined
organic phases were washed successively with saturated
À1
2
3
trin capillary column and N as carrier gas. For the measure-
2
ments, (S)-2a and (S)-2b were silylated with N,O-bis(trime-
thylsilyl)acetamide (BSA). GC-MS analyses were performed
using a HP 6890 Series instrument with a mass selective de-
tector 5973. A HP-5 Crosslinked Methyl Silicone Gum ca-
pillary column was used as stationary phase, and helium as
carrier gas. Optical rotations ([a]) were measured in silica
glass cuvettes using a Perkin–Elmer 343plus instrument.
aqueous NaHCO (2”300 mL) and water (300 mL). The or-
3
ganic phase was dried over Na SO , and the solvent was
2
4
evaporated. The crude product was purified by kugelrohr
distillation (1598C, 4.6 mbar), and the ketone 1a was ob-
tained as colorless liquid; yield: 1.78 g (10.9 mmol, 55%).
1
3
H NMR (300 MHz, CDCl ): d=0.83–0.87 (t, 3H, JH,H
=
3
1
-Chloro-2-octanone (1a)
6.6 Hz, H-8), 1.26 (m, 6H, H-5-H-7), 1.56–1.61 (m, 2H, H-
3
4
), 2.53–2.58 (t, 2H, J =7.4 Hz, H-3), 4.05 (s, 2H, H-1);
H,H
Preparation via a two-step procedure: 1-Octene (11.8 mL,
13
C NMR (APT, 75 MHz, CDCl ): d=13.9, 22.4, 23.5, 28.7,
3
7
3
7
5.0 mmol, 1.00 equiv.) was dissolved in 188 mL acetone,
8.0 mL water, and trichloroisocyanuric acid (17.4 g,
5.0 mmol, 1.00 equiv.) was added. The mixture was stirred
3
2
1
1.4, 39.6, 48.1, 202.7; FT-IR (ATR-film): n˜ =2948, 2921,
853, 1728, 1714 (all s), 1463, 1456, 1398, 1374 (all m), 1320,
289, 1272, 1255, 1228, 1191, 1164 (all w), 1126 (m), 1099
at room temperature for 1.0 h. The mixture was then filtered
through celite, and the filtrate was extracted 3 times with
(
w), 1058 (m), 1007, 905, 888 (all w), 766, 725 (both m), 708,
54, 647 cm (all w). GC-MS [708C (3.00 min), 108Cmin ,
À1
À1
6
2
8
250 mL CH Cl . The organic phase was dried over Na SO ,
2
2
2
4
808C (10.0 min)]: t =8.80 min, m/z=114/113, 105, 95/92,
R
and the solvent was evaporated. The crude product was dis-
solved in 150 mL CH Cl and cooled in an ice bath. Trichloro-
À1
5, 77, 69, 57/55. GC [1258C (20.0 min), 208Cmin , 1708C
2
2
(
5.00 min)]: t =11.51 min. Analytical data were in agree-
R
[20]
isocyanuric acid (17.4 g, 75.0 mmol, 1.00 equiv.) and
TEMPO (0.59 g, 3.75 mmol, 0.05 equiv.) were added. The
mixture was stirred with cooling for 10.0 min. Then the ice
bath was removed and the mixture was stirred at room tem-
perature for another 3.0 h. The mixture was then filtered
through celite and the filtrate was washed successively with
saturated aqueous NaHSO , saturated aqueous Na CO ,
aqueous HCl (1.0M) and saturated aqueous NaCl (450 mL
each). The organic phase was dried over Na SO , and the
solvent was evaporated. The crude product was purified by
kugelrohr distillation (1258C, 2.6 mbar) and column chroma-
tography (silica gel, cyclohexane/CH Cl , 1:1). The ketone
ment with the literature reports.
1-Bromo-2-octanone (1b)
1-Bromo-2-octanone 1b was prepared following a literature
3
2
3
[16]
procedure. First, Jones reagent was prepared as follows:
CrO3 (8.70 g, 87.0 mmol, 1.30 equivs.) was dissolved in
9.00 mL water and 6.00 mL H SO dissolved in 9.00 mL
2
4
2
4
H O were added. The mixture was stirred for 10.0 min at
2
room temperature. During this time 1-octene (10.5 mL,
66.9 mmol, 1.00 equiv.) was dissolved in 75.0 mL acetone
and 3.00 mL water were added. The mixture was cooled in
an ice bath and then the Jones reagent was added. During
the next 10.0 min NBS (17.9 g, 100 mmol, 1.50 equivs.) was
added. The ice bath was removed and the mixture was
stirred at room temperature for another 3.0 h. Water was
added and the mixture was extracted 3 times with 150 mL
diethyl ether. The combined organic phases were washed 3
times with 450 mL water. The organic phase was dried over
2
2
1
a was obtained as colorless liquid; yield: 10.1 g (62.2 mmol,
1
8
3%). H NMR (300 MHz, CDCl ): d=0.84–0.88 (t, 3H,
3
3
JH,H =6.9 Hz, H-8), 1.26–1.27 (m, 6H, H-5-H-7), 1.54–1.64
3
(
m, 2H, H-4), 2.53–2.58 (t, 2H, J =7.5 Hz, H-3), 4.06 (s,
H,H
13
2
2
2
1
1
1
6
2
8
H, H-1); C NMR (APT, 75 MHz, CDCl ): d=13.9, 22.4,
3
3.5, 28.7, 31.4, 39.7, 48.2, 202.6; FT-IR (ATR-film): n˜ =
948, 2921 (both s), 2853 (m), 1731, 1714 (both s), 1537,
503 (both w), 1463, 1456, 1398, 1374 (all m), 1316, 1293,
276, 1265, 1228, 1191, 1160 (all w), 1126 (m), 1102 (w),
058 (m), 1011, 905, 888, (all w), 766, 725 (both m), 708,
50 cm (both w); GC-MS [708C (3.00 min), 108Cmin ,
808C (10.0 min)]: t =9.01 min, m/z=114/113, 105, 95, 92,
5, 77, 69, 57/55; GC [1258C (20.0 min), 208Cmin , 1708C
MgSO , and the solvent was evaporated. The crude product
4
À1
À1
was purified by kugelrohr distillation (1158C, 2.6 mbar) and
column chromatography (silica gel, cyclohexane/CH Cl ,
R
2
2
À1
1:1). The ketone 1b was obtained as a colorless liquid yield:
1
(
5.00 min)]: t =11.47 min; DC: R =0.51 (silica gel, cyclo-
5.87 g (28.3 mmol, 42%). H NMR (300 MHz, CDCl ): d=
R
f
3
3
hexane/CH Cl , 1:1). Analytical data were in agreement
with the literature reports.
0.85–0.89 (t, 3H, J =6.8 Hz, H-8), 1.28 (m, 6H, H-5 to
H-7), 1.55–1.65 (m, 2H, H-4), 2.61–2.66 (t, 2H, JH,H
7.4 Hz, H-3), 3.87 (s, 2H, H-1); C NMR (APT, 75 MHz,
2
2
H,H
[20]
3
=
1
3
Preparation via a two-step/one-pot procedure: 1-Octene
(
3.14 mL, 20.0 mmol, 1.00 equiv.) was dissolved in 20.0 mL
CDCl ): d=13.9, 22.4, 23.7, 28.6, 31.4, 34.3, 39.7, 202.1; FT-
3
acetone and 0.40 mL water was added. The mixture was
cooled in an ice bath, and trichloroisocyanuric acid (2.32 g,
IR (ATR-film): n˜ =2948, 2925, 2854, 1712 (all s), 1465, 1403,
1374 (all m), 1204 (w), 1173 (m), 1116 (w), 1057 (m), 892,
À1
10.0 mmol, 0.50 equiv.) dissolved in 30.0 mL acetone was
722, 688, 628, 610 cm (all w); GC-MS [708C (3.00 min),
À1
added. Then Bu NBr (0.13 g, 0.40 mmol, 0.02 equiv.) dis-
108Cmin , 2808C (10.0 min)]: t =10.00 min, m/z (%)=
4
R
solved in 4.00 mL water, 66.0 mL phosphate buffer (1.0M,
138/136, 123/121, 114/113, 97/95, 85, 69, 57/55; GC [1258C
À1
pH 5.2), RuCl ·XH O (~41%) (0.13 g, 0.20 mmol,
(20.0 min), 208Cmin , 1708C (5.00 min)]: t =17.63 min;
3
2
R
Adv. Synth. Catal. 2007, 349, 2697 – 2704
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
2701

Albrecht Berkessel et al.
UPDATES
À1
DC: R =0.48 (silica gel, cyclohexane/CH Cl 1 : 1). Analyti-
cal data were in agreement with the literature.
7.4·10 mbar). (S)-1-Bromo-2-octanol [(S)-2b] was obtained
as a colorless liquid; yield: 5.49 g (26.3 mmol, 89%; >99%
f
2
2
[16]
2
0
1
ee); [a] : À14.88 (c 1.00, EtOH); ee >99%; H NMR
D
3
(
300 MHz, CDCl ): d=0.86–0.90 (t, 3H, J =6.9 Hz, H-8),
General Procedure for the Enantioselective
Biocatalytic Synthesis of (S)-1-Halo-2-octan-ols (S)-2
3
H,H
1
3
(
.28–1.56 (m, 10H, H-3-H-7), 2.16–2.17 (m, 1H, OH), 3.35–
.41 (dd, 1H, J =10.2 Hz, J =6.9 Hz, H-1 ), 3.52–3.56
2
3
H,H
H,H
a
(
According to the Reaction Shown in Table 1)
2
3
dd, 1H, J =10.4 Hz, J =3.2 Hz, H-1 ), 3.76–3.77 (m,
H,H H,H b
13
A Titrino reaction apparatus was filled with 20 mL of an
aqueous buffer solution (0.2M; adjusted to pH 7.0), the
whole-cell catalyst of type E. coli DSM14459 [overexpress-
ing the (R)-alcohol dehydrogenase from L. kefir and glucose
dehydrogenase from T. acidophilum; cell concentration
1H, H-2); C NMR (APT, 75 MHz, CDCl ): d=14.0, 22.5,
3
25.6, 29.1, 31.7, 35.1, 40.7, 71.1; FT-IR (ATR-film): n˜ =3390,
2948, 2921, 2854 (all s), 1464, 1456, 1418, 1374 (all m), 1266
(w), 1219 (m), 1177, 1150 (both w), 1123, 1068 (both m),
1034 (s), 963, 936, 899, 868, 831, 790 (all w), 722 (m),
À1
À1
~
50–56 g of wet biomass/L], d-glucose (1.1 equivs. based on
the amount of ketone) and 20 mmol (0.5M), 30 mmol
0.75M) or 40 mmol (1.0M) of ketone 1 (see entries 1–4 in
661 cm (s); GC-MS [708C (3.00 min), 108Cmin , 2808C
(10.0 min)]: t
=10.35 min, m/z=125/123, 115, 98/97, 81, 69,
R
À1
(
57/56/55; GC [1258C (20.0 min), 208Cmin , 1708C
Table 1). Water was added until a volume of 40 mL is
reached. The reaction mixture was stirred at room tempera-
ture for 22–24 h and the pH was maintained at ~6.5 by
dosage of aqueous sodium hydroxide (5.0M NaOH). After
a reaction time of 22–24 h the conversion has been deter-
mined by means of HPLC-chromatography and NMR-spec-
troscopy, respectively. The work-up was carried out by low-
ering the pH to <3 with concentrated hydrochloric acid and
addition of 3.0 g of the filter aid material Celite Hyflo Su-
percel to the reaction mixture, and subsequent filtration.
(5.00 min)]:
t
R
=19.05 min [(S)-product, major],
t =
R
19.64 min [(R)-product, minor]. The absolute configuration
of the major enantiomer was assigned as (À)-S, based on
comparison of the optical rotation for the (+)-R enantiomer.
The (+)-R enantiomer was prepared by kinetic resolution of
rac-1-octene oxide and nucleophilic ring opening of the
[18]
(+)-R enantiomer by LiBr. Analytical data were in agree-
ment with the literature.
[21]
The filter cake was washed with 3”50 mL of MTBE, and (S)-1-Octene oxide [(S)-3]
the aqueous phase was extracted accordingly with the result-
Preparation starting from (S)-1-Chloro-2-octanol [(S)-2a]:
S)-1-Chloro-2-octanol [(S)-2a] (0.88 g, 5.33 mmol,
.00 equiv.) was dissolved in 3.00 mL diethyl ether, and
ing organic fractions. After drying over magnesium sulfate
the collected organic phases were concentrated to dryness,
delivering the desired optically active alcohols in a high
purity, even as a crude product.
(
1
sodium hydroxide (2.13 g, 53.3 mmol, 10.0 equivs.) was
added. The mixture was stirred for one hour at 308C. Then
the solvent was evaporated and the crude product was puri-
fied by bulb-to-bulb distillation (608C, 3.00 mbar). The ep-
oxide (S)-3 was obtained as colorless liquid; yield: 0.63 g
(
S)-1-Chloro-2-octanol [(S)-2a]
1.33 g of the crude product obtained by extraction of the
2
D
0
(
4.90 mmol, 92%; >99% ee); [a] : À15.08 (c 1.00, EtOH);
asymmetric biocatalytic reduction of 1-chloro-2-octanone
[19]
23
D
ee> 99% {Lit. [a] : À14.08 (c 2.10, EtOH); ee >97%};
(
7
1a) were subjected to kugelrohr distillation (1178C,
.2·10 mbar). (S)-1-Chloro-2-octanol [(S)-2a] was obtained
1
3
À1
H NMR (300 MHz, CDCl ): d=0.85–0.90 (t, 3H,
J
=
H,H
3
6
.8 Hz, H-8), 1.24–1.53 (m, 10H, H-3-H-7), 2.44–2.46 (dd,
as a colorless liquid; yield: 1.23 g (7.45 mmol, 92%; >99%
2
3
2
D
0
1
1
H, J =5.1 Hz, J =2.7 Hz, H-1 ), 2.72–2.75 (dd, 1H,
H,H H,H a
3
ee); [a] :=À16.78 (c 1.00, EtOH); ee >99%; H NMR
2
J
=5.0 Hz, J =4.1 Hz, H-1 ), 2.86–2.92 (m, 1H, H-2);
H,H b
(
300 MHz, CDCl ): d=0.87–0.88 (3H, H-8), 1.29–1.51 (m,
0H, H-3-H-7), 2.27 (s, 1H, OH), 3.43–3.50 (dd, 1H, J
1.1 Hz, JH,H =7.2 Hz, H-1 ), 3.59–3.64 (dd, 1H, JH,H
1.1 Hz, JH,H =3.3 Hz, H-1 ), 3.78–3.79 (m, 1H, H-2);
H,H
3
1
3
2
C NMR (APT, 75 MHz, CDCl ): d=14.0, 22.5, 25.9, 29.1,
1
1
1
=
=
3
H,H
3
2
3
1.7, 32.5, 47.1, 52.4; FT-IR (ATR-film): n˜ =2948, 2921, 2846
a
3
(
all s), 1466, 1456, 1449 (all m), 1408, 1378, 1296, 1255, 1221,
b
1
3
1
191, 1126, 1099, 1079, 1055, 1024, 929 (all w), 916 (m), 882
C NMR (APT, 75 MHz, CDCl ): d=14.0, 22.5, 25.4, 29.1,
3
À1
(
w), 831 (m), 814, 759 (both w), 729 (m), 678 cm (w); GC-
3
2
1
9
1.7, 34.2, 50.5, 71.4; FT-IR (ATR-film): n˜ =3369, 2948,
922, 2855 (all s), 1463, 1457, 1429, 1374 (all m), 1337, 1300,
279, 1252, 1218, 1191, 1167 (all w), 1123 (m), 1050 (s), 966,
À1
MS [708C (3.00 min), 108Cmin , 2808C (10.0 min)]: t =
R
5
.82 min, m/z=99, 85/81, 71/70/69/68/67, 58/57/56/55; GC
À1
À1
À1
[
608C (48.0 min), 58Cmin , 1208C (35.0 min), 158Cmin ,
43, 892, 875, 848, 790 (all w), 739, 698 cm (both m); GC-
À1
1
808C (3.00 min)]: t =33.55 min [(R)-product, minor], t =
MS [708C (3.00 min), 108Cmin , 2808C (10.0 min)]: t =
R
R
R
3
4.36 min [(S)-product, major]. The absolute configuration
9
.11 min, m/z=115, 98/97, 81/79, 70/69, 57/56/55; GC [1258C
À1
of the major enantiomer was assigned as (À)-S, based on
(
20.0 min), 208Cmin , 1708C (5.00 min)]: t =13.40 min
R
comparison of the measured optical rotation with the litera-
[
(S)-product, major], t =13.85 min [(R)-product, minor].
R
[19]
ture value. Analytical data were in agreement with the lit-
The absolute configuration of the major enantiomer was as-
[22]
erature.
signed as (À)-S, based on comparison of the measured opti-
[
11,12a]
Preparation starting from (S)-1-Bromo-2-octanol [(S)-
b]: (S)-1-Bromo-2-octanol [(S)-2b] (5.12 g, 24.5 mmol,
.00 equiv.) was dissolved in 15.0 mL diethyl ether, and
cal rotation with the literature values.
were in agreement with the literature.
Analytical data
[
12a]
2
1
sodium hydroxide (9.80 g, 0.24 mol, 10.0 equivs.) was added.
The mixture was stirred for one hour at 308C. Then the sol-
vent was evaporated and the crude product was purified by
bulb-to-bulb distillation (558C, 2.00 mbar). The epoxide (S)-
3 was obtained as colorless liquid; yield: 2.89 g (22.5 mmol,
(
S)-1-Bromo-2-octanol [(S)-2b]
6
.18 g of the crude product obtained by extraction of the
asymmetric biocatalytic reduction of 1-bromo-2-octanone
(
1b) were subjected to kugelrohr distillation (1298C,
2702
asc.wiley-vch.de
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2007, 349, 2697 – 2704

Two-Step Synthesis of an Enantiopure Aliphatic Terminal (S)-Epoxide
UPDATES
2
D
0
9
2%; >99% ee; [a] : À15.18 (c 1.00, EtOH); ee >99%
Chem. Soc. 2006, 128, 14006–14007; d) K. Matsumoto,
Y. Sawada, B. Saito, K. Sakai, T. Katsuki, Angew.
Chem. Int. Ed. 2005, 44, 4935–4939; e) Y. Sawada, K.
Matsumoto, S. Kondo, H. Watanabe, T. Ozawa, K.
Suzuki, B. Saito, T. Katsuki, Angew. Chem. Int. Ed.
2006, 45, 3478–3480.
[19]
23
D
1
{Lit.
[a] : À14.08 (c 2.10, EtOH); ee >97%}; H NMR
3
(
300 MHz, CDCl ): d=0.85–0.89 (t, 3H, J =6.8 Hz, H-8),
3
H,H
2
1
5
3
.24–1.52 (m, 10H, H-3-H-7), 2.43–2.46 (dd, 1H, JH,H
.0 Hz, JH,H =2.9 Hz, H-1 ), 2.71–2.74 (dd, 1H, JH,H
.9 Hz, JH,H =5.1 Hz, H-1 ), 2.86–2.92 (m, 1H, H-2);
C NMR (APT, 75 MHz, CDCl ): d=14.0, 22.5, 25.9, 29.1,
1.7, 32.5, 47.1, 52.4; FT-IR (ATR-film): n˜ =3037 (w), 2948,
921, 2853 (all s), 1480 (w), 1463, 1456 (both m), 1408, 1374,
327, 1303, 1255, 1221, 1191, 1126, 1070, 1048, 990, 929 (all
w), 916 (m), 885 (w), 831 (s), 780, 756, 735, 722 cm (all w);
GC-MS [708C (3.00 min), 108Cmin , 2808C (10.0 min)]:
t =5.82 min, m/z=99, 85/81, 71/70/69/68/67, 58/57/56/55;
GC [608C (48.0 min), 58Cmin , 1208C (35.0 min),
58Cmin , 1808C (3.00 min)]: t =33.92 min [(R)-product,
=
=
3
3
a
2
b
13
3
[6] a) D. E. White, E. N. Jacobsen, Tetrahedron: Asymme-
try 2003, 14, 3633–3638; b) S. S. Thakur, W. Li, S.-J.
Kim, G.-J. Kim, Tetrahedron Lett. 2005, 46, 2263–2266.
7] a) H. Ohta, H. Tetsukawa, J. Chem. Soc., Chem.
Commun. 1978, 849–850; b) H. Ohta, H. Tetsukawa,
Agric. Biol. Chem. 1979, 43, 2099–2104.
3
2
1
[
À1
À1
R
[
8] T. Kubo, M. W. Peters, P. Meinhold, F. H. Arnold,
À1
Chem. Eur. J. 2006, 12, 1216–1220.
À1
1
R
[
9] For a review, see: K. Faber, Biotransformations in Or-
minor], t =34.70 min [(S)-product, major]. The absolute
th
R
ganic Chemistry, 5 edn., Springer-Verlag, Berlin, 2004,
configuration of the major enantiomer was assigned as (À)-
chapter 2.3.2.3, p 236f.
S, based on comparison of the measured optical rotation
[
[
[
10] For a review, see: K. Faber, Biotransformations in Or-
[19]
with the literature value. Analytical data were in agree-
ment with the literature.
th
ganic Chemistry, 5 edn., Springer-Verlag, Berlin, 2004,
[22]
chapter 2.1.5, p 135f.
11] T. M. Poessl, B. Kosjek, U. Ellmer, C. C. Gruber, K.
Edegger, P. Hildebrandt, K. Faber, U. T. Bornscheuer,
W. Kroutil, Adv. Synth. Catal. 2005, 347, 1827–1834.
12] a) For early work on the reduction of a-halogenated
alkan-2-ones, see: T. Sakai, K. Wada, T. Murakami, K.
Kohra, N. Imajo, T. Ooga, S. Tsuboi, A. Takeda, M.
Utaka, Bull. Chem. Soc., Jpn. 1992, 65, 631–638;
b) For reviews about the biocatalytic reduction in gen-
eral, see: W. Hummel, Adv. Biochem. Eng./Biotechnol.
Acknowledgements
We thank Dr. F.-R. Kunz and Dr. M. Janik and their teams
Degussa, AQura GmbH) for carrying out chiral GC analy-
ses as well as recording NMR spectra. This work was sup-
ported by the Federal Ministry of Education and Research
BMBF) within the support programme “Biotechnologie
000 – Nachhaltige BioProduktion” (Project: “Entwicklung
eines biokatalytischen und nachhaltigen Verfahrens zur in-
dustriellen Herstellung enantiomerenreiner Amine und Alko-
hole unter besonderer Berücksichtigung der Atomçkono-
mie”), and by the Fonds der Chemischen Industrie.
(
(
2
1
997, 58, 146–184; K. Faber, Biotransformations in Or-
th
ganic Chemistry, 5 edn., Springer-Verlag, Berlin, 2005,
chapter 2.2, p 177f.
[
[
13] B. Seisser, I. Lavandera, K. Faber, J. H. L. Spelberg, W.
Kroutil, Adv. Synth. Catal. 2007, 349, 1399–1404.
14] H. Grçger, F. Chamouleau, N. Orologas, C. Rollmann,
K. Drauz, W. Hummel, A. Weckbecker, O. May,
Angew. Chem. Int. Ed. 2006, 45, 5677–5681.
15] For reviews on the reduction of ketones with whole-
cell biocatalysts, in general, see: a) M. Kataoka, K.
Kita, M. Wada, Y. Yasohara, J. Hasegawa, S. Shimizu,
Appl. Microbiol. Biotechnol. 2003, 62, 437–445; b) S.
Buchholz, H. Grçger, in: Biocatalysis in the Pharma-
ceutical and Biotechnology Industries, (Ed.: R. N.
Patel), CRC Press, New York, 2006, chapter 32, p 757–
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