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K. Matsumoto et al.
LETTER
(5) Recent reviews for enzymatic deracemization:
(a) Fotheringham, I.; Archer, I.; Carr, R.; Speight, R.;
Turner, N. J. Biochem. Soc. Trans. 2006, 34, 287.
(b) Strauss, U. T.; Felfer, U.; Faber, K. Tetrahedron:
Asymmetry 1999, 10, 107. (c) Kroutil, W.; Faber, K.
Tetrahedron: Asymmetry 1998, 9, 2901.
(6) (a) Larissegger, B.; Kroutil, W.; Faber, K. Synlett 2005,
1936. (b) Carr, R.; Alexeeva, M.; Dawson, M. J.; Gotor-
Fernandez, V.; Humphrey, C. E.; Cara, E.; Turner, N. J.
ChemBioChem 2005, 6, 637. (c) Cardus, G. J.; Carnell, A.
J.; Trauthwein, H.; Riemeir, T. Tetrahedron: Asymmetry
2004, 15, 239. (d) Beard, T. M.; Turner, N. J. Chem.
Commun. 2002, 246.
(7) (a) Baskar, B.; Pandian, N. G.; Priya, K.; Chadha, A.
Tetrahedron 2005, 61, 12296. (b) Mitsukura, K.; Yoshida,
T.; Nagasawa, T. Biotechnol. Lett. 2002, 24, 1615.
(c) Rhys-Williams, W.; Thomason, M. J.; Hung, Y.-F.;
Hanlon, G. W.; Lloyd, A. W. Chirality 1998, 10, 528.
(d) Reichel, C.; Brugger, R.; Bang, H.; Geisslinger, G.;
Brune, K. Mol. Pharmacol. 1997, 51, 576. (e) Rhys-
Williams, W.; Thomason, M. J.; Lloyd, A. W.; Hanlon, G.
W. Pharm. Sci. 1996, 2, 537. (f) Menzel, S.; Waibel, R.;
Brune, K.; Geisslinger, G. Biochem. Pharmocol. 1994, 48,
1056.
(8) (a) Kato, D.-I.; Miyamoto, K.; Ohta, H. Biocatal.
Biotransform. 2005, 23, 375. (b) Kato, D.-I.; Miyamoto, K.;
Ohta, H. Tetrahedron: Asymmetry 2004, 15, 2965. (c)Kato,
D.-I.; Satoshi, M.; Ohta, H. J. Org. Chem. 2003, 68, 7234.
(d) Kato, D.-I.; Satoshi, M.; Ohta, H. Org. Lett. 2002, 4, 371.
(9) Pirkle, W. H.; Reno, D. S. J. Am. Chem. Soc. 1987, 109,
7189.
(12) The substrate ( )-1 was easily prepared from ( )-lactic acid
in four steps. The details of this synthesis have been reported
in ref. 13.
(13) Matsumoto, K.; Okamoto, T.; Otsuka, K. Bull. Chem. Soc.
Jpn. 2004, 77, 2051.
(14) The absolute configuration of 1 was confirmed by
comparing the obtained optical rotation value with the
reported value: Lit.21 [a]D24 –45.9 (c 1.16, CHCl3), S-form.
(15) The ee of 1 was determined by HPLC analysis with
CHIRALCEL OJ (Daicel Chemical Industries, Ltd.); eluent,
hexane–2-PrOH = 180:1; flow rate, 0.5 mL min–1; tR = 40
(R) and 50 (S) min.
(16) The deracemization did not occur for the reactions using the
other TADDOL derivatives bearing a cyclopentane ring and
a dimethyl group [(–)-2,2-tetramethylene- and 2,2-dimethyl-
a,a,a¢,a¢-tetraphenyl-1,3-dioxolan-4,5-dimethanol,
respectively], (+)-1,1¢-bi-2-naphthol, and (–)-hydrobenzoin
as chiral host compounds under the same conditions.
(17) Although the ee of (S)-1 increased according to the extension
of the reaction time (42% ee for one day), the reaction for
over three days gave almost the same result as that of the
three-day reaction. We then decided that the racemizations
in all cases were carried out for three days.
(18) The reaction using EtOH, i-PrOH, t-BuOH, and cyclohexane
as an alternative mix solvent with H2O gave only the
racemate 1.
(19) A white solid was obtained by filtration when a sat. NH4Cl
aq and EtOAc were not added to the reaction mixture. ESI-
TOFMS analysis of the collected solid showed the peak of [1
+ 2 + Na]+ ion (m/z = 721.3 for C46H50O6Na) in the same
manner as the case of the optical resolution.13 The peak
would mean the construction of the 1:1 inclusion complex (1
and 2) in the reaction mixture.
(10) (a) Toda, F.; Mori, K. J. Chem. Soc., Chem. Commun. 1986,
1357. (b) Brussee, J.; Groenendijk, J. L. G.; te Koppele, J.
M.; Jansen, A. C. A. Tetrahedron 1985, 41, 3313. (c) Toda,
F.; Tanaka, K. Chem. Lett. 1983, 12, 661.
(20) The ee of the products can be improved by a sequential
optical resolution using (–)-2 without a base.13
(11) (a) Kaku, H.; Okamoto, N.; Nakamura, A.; Tsunoda, T.
Chem. Lett. 2004, 33, 516. (b) Kaku, H.; Takaoka, S.;
Tsunoda, T. Tetrahedron 2002, 58, 3401. (c) Kaku, H.;
Ozako, S.; Kawamura, S.; Takatsu, S.; Ishii, M.; Tsunoda, T.
Heterocycles 2001, 55, 847. (d) Tsunoda, T.; Kaku, H.;
Nagaku, M.; Okuyama, E. Tetrahedron Lett. 1997, 38, 7759.
(21) Matsumoto, K.; Suzuki, N.; Ohta, H. Tetrahedron Lett.
1990, 31, 7159.
Synlett 2007, No. 5, 729–732 © Thieme Stuttgart · New York