DEDICATED CLUSTER
UPDATES
Harald Grçger et al.
a glucose dehydrogenase from Thermoplasma acidophilum, References
has been described in ref.[4c] The corresponding cell pellets
were – after storage at À208C – used in the reduction of4-
[1] a) J. A. Gladysz, D. P. Curran, I. T. Horvath (Eds.),
Handbook of Fluorous Chemistry, Wiley-VCH, Wein-
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[2] For selected examples ofchemocatalytic reduction of
fluorinated ketones, see: a) J. Wu, H. Chen, W. Kwok,
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2004, 60, 7411–7417; d) review: R. Noyori, T. Ohkuma,
Angew. Chem. 2001, 113, 40–75.
[3] For selected recent examples ofbiocatalytic reduction of
fluorinated ketones, see: a) M. J. Homann, R. B. Vail, E.
Previte, M. Tamarez, B. Morgan, D. R. Dodds, A. Zaks,
Tetrahedron 2004, 60, 789–797; b) R. N. Patel, A. Gos-
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R. Johnston, P. J. Siva, B. Nielsen, J. Fan, W. He, Z. Shi,
K. Y. Wang, R. Eiring, D. Cazzulino, A. Singh, R. Muel-
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R. N. Patel, Adv. Synth. Catal. 2005, 347, 1073–1080;
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Chen, J. Moore, Tetrahedron: Asymmetry 2006, 17, 554–
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[4] For the development ofthis recombinant whole-cell
redox technology platform and their applications in pro-
cesses for reductive amination (ref.[4a,b]) and reduction
(ref.[4c]), see: a) A. Menzel, H. Werner, J. Altenbuchner,
H. Grçger, Eng. Life Sci. 2004, 4, 573–576; b) H.
Grçger, O. May, H. Werner, A. Menzel, J. Altenbuchner,
Org. Proc. Res. Developm. 2006, 10, 666–669; c) H.
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fluoroacetophenone, 1a, as described in the procedure
below.
Procedure for the Biocatalytic Synthesis of (R)-4-
Fluorophenylethan-1-ol via Reduction of 4-
Fluoroacetophenone at a 0.5M Substrate
Concentration
In a Titrino-reaction apparatus, 3.55 g ofthe whole cell cata-
lyst E.coli DSM14459, containing an (R)-alcohol dehydro-
genase from L. kefir as well as a glucose dehydrogenase
from Thermosplasma acidophilum, leading to a cell concen-
tration of71 g ofwet biomass per L reaction volume,
29.3 mmol of d-glucose (1.18 equivalents referring to the
molar amount ofketone 1a) and 24.8 mmol of4-lfuoroace-
tophenone, 1a (directly used as commercially available
sample, which was purchased from Merck KgaA, Germany),
are added to 20 mL of an aqueous phosphate buffer solution
(0.2M; adjusted to pH 7.0). Then, water is added until a
volume of50 mL is reached. The reaction mixture is stirred
at room temperature, and the pH is kept constantly at ~6.5
by dosage ofaqueous sodium hydroxide (5 M NaOH). After
a reaction time of23 h, a conversion of >95% has been
achieved (according to HPLC and NMR spectroscopy). The
work-up was carried out by decreasing the pH to 2 to 3 with
concentrated hydrochloric acid and addition of5.2 g ofthe
filter aid material Celite Hyflo Supercel to the reaction mix-
ture, and subsequent filtration. The filter cake was washed 3
times with 50 mL ofMTBE, and the aqueous phase was ex-
tracted with the three obtained organic MTBE fractions.
After drying over magnesium sulfate the collected organic
phases were evaporated. Subsequently, the resulting crude
product was distilled in vacuum (3.5 mbar) by means ofa
short-path distillation furnishing the purified (R)-4-flurophe-
nylethan-1-ol, (R)-2a; yield: 87%, >99% ee.
Acknowledgements
The authors thank the Federal Ministry of Education and Re-
search (BMBF) for support of the project Entwicklung eines
biokatalytischen und nachhaltigen Verfahrens zur industriell-
en Herstellung enantiomerenreiner Amine und Alkohole
unter besonderer Berücksichtigung der Atomçkonomie (De-
velopment of a biocatalytic and sustainable process for the in-
dustrial production of enantiomerically pure amines and al-
cohols under particular consideration of the atom economy)
within the support programme Biotechnologie 2000 – Nach-
haltige BioProduktion (Biotechnology 2000 – Sustainable
BioProduction). For carrying out chiral HPLC analyses as
well as NMR spectroscopic measurements thanks are due to
Dr. F.-R. Kunz and Dr. M. Janik and their teams (Degussa,
AQura GmbH). The support of Dr. U. Becker and his team
in the preparation of the biocatalyst is also gratefully ac-
knowledged.
[5] Glucose dehydrogenase-based cofactor regeneration
with whole cell biocatalysts, based on the pioneering
work by the Shimizu group, has been successfully ap-
plied in ketone reduction for the synthesis of optically
active alcohols; for reviews, see: a) M. Kataoka, K. Kita,
M. Wada, Y. Yasohara, J. Hasegawa, S. Shimizu, Appl.
Microbiol. Biotechnol. 2003, 62, 437–445; b) S. Buch-
holz, H. Grçger, in: Biocatalysis in the Pharmaceutical
and Biotechnology Industries, (Ed.: R. N. Patel), CRC
Press, New York, 2006, chapter 32.
[6] H. Grçger, W. Hummel, C. Rollmann, F. Chamouleau,
H. Hꢂsken, H. Werner, C. Wunderlich, K. Abokitse, K.
Drauz, S. Buchholz, Tetrahedron 2004, 60, 633–640.
[7] W. Hummel, M.-R. Kula, (FZ Jꢂlich GmbH), European
Patent EP 456107, 1991.
712
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Adv. Synth. Catal. 2007, 349, 709 – 712