Synthesis and Inhibitory Activities of Hyacinthacines A and A Stereoisomers
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COMMUNICATIONS
This methodology may become more advantageous Supporting Information
with the use of dihydroxyacetone (DHA) and borate
as DHAP mimic in RhuA-catalyzed reactions.
Modification of FruA and FucA by protein engineer-
ing to increase their tolerance towards (R)- and (S)-
prolinal and their derivatives is currently in progress.
This may lead to new derivatives with optimized in-
hibitory activity against glycosidases.
Experimental preparations, analytical data, biological data
and H, C NMRspectra for all compounds; COSY, HSQC
and NOE spectra, are described in detail.
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26]
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Acknowledgements
Financial support from the Spanish MEC (CTQ2005–25182-
E, CTQ2006–01080 and CTQ2006–01345/BQU), La Marató
de TV3 foundation (Ref: 050931) and Generalitat de Catalu-
nya DURSI 2005-SGR-00698 is acknowledged. J. Calveras
acknowledges the CSIC UAs pre-doctoral scholarship pro-
grams.
Experimental Section
Synthetic and analytical procedures are described in the
Supporting Information. A typical synthesis of hyacinthacine
stereoisomers is described below.
References
Enzymatic Aldol Condensations
(
(
(
S)-Prolinal (16.1 mmol, 3.75 g) was dissolved in DMF
22.5 mL) and cooled to 08C. Then, the DHAP solution
9.5 mmol, 90 mL of a 105.2 mM solution, at pH 6.9, freshly
[
[
[
1] A. Kato, I. Adachi, M. Miyauchi, K. Ikeda, T. Komae,
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Kato, I. Adachi, A. A. Watson, R. J. Nash, G. W. J.
Fleet, Tetrahedron: Asymmetry 2000, 11, 1–8.
prepared) was added at 48C under vigorous agitation. Then,
RhuA (225U) was added and mixed again. The reaction was
shaken (100 rpm) at 48C and when it reached a constant
conversion, MeOH (115 mL) was added. Then, excess of al-
dehyde was removed by extractions with ethyl acetate (2
3] T. D. Heightman, A. T. Vasella, Angew. Chem. 1999,
1
7
11, 794–815; Angew. Chem. Int. Ed. 1999, 38, 750–
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5
0 mL). The solution of the product obtained (100 mL) was
À1
treated with acid phosphatase (50 mg, 7 U mg ) at pH 5.5.
The unphosphated product was desalted by RP-HPLC and
after lyophilization a pale brown solid was obtained; yield:
Chem. Biol. 2002, 6, 619–629; T. D. Butters, R. A.
Dwek, F. M. Platt, Curr. Top. Med. Chem. 2003, 3, 561–
5
74; N. G. Oikonomakos, C. Tiraidis, D. D. Leonidas,
1
.03 g (58% overall).
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This solid was dissolved in H O/EtOH (4:1; 160 mL) and
2
Pd/C (200 mg) added. The reaction mixture was stirred
under hydrogen gas (50 psi) overnight at room temperature.
After removal of the catalyst by filtration through neutral-
ized and deactivated aluminum, the diasteromeric mixture
of 6 and 7 was obtained as a brown solid; yield: 514 mg
5
687–5701.
[
4] A. A. Watson, G. W. J. Fleet, N. Asano, R. J. Molyneux,
R. J. Nash, Phytochemistry 2001, 56, 265–295.
[
5] R. J. Molyneux, M. Benson, R. Y. Wong, J. E. Tropea,
A. D. Elbein, J. Nat. Prod. 1988, 51, 1198–1206; J. E.
Tropea, R. J. Molyneux, G. P. Kaushal, Y. T. Pan, M.
Mitchell, A. D. Elbein, Biochemistry 1989, 28, 2027–
(
77%).
A similar procedure was followed starting with the (R)-
Cbz-prolinal obtaining the mixture of diastereoisomers 8
and 9 as pale brown solid; yield: 656 mg (90%).
2
034; R. J. Nash, L. E. Fellows, J. V. Dring, G. W. J.
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Purification by Ion Exchange Chromatography
The diasteromeric mixture 8+9 (50 mg) was separated by
[7] I. Izquierdo, M. T. Plaza, R. Robles, F. Franco, Tetrahe-
ion exchange chromatography on a FPLC system. CM-Se-
dron: Asymmetry 2001, 12, 2481–2487.
+
pharose CL-6B (Amersham Pharmacia) in the NH4 form
[8] I. Izquierdo, M. T. Plaza, F. Franco, Tetrahedron: Asym-
metry 2003, 14, 3933–3935; L. Rambaud, P. Compain,
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1809; T. Yamashita, K. Yasuda, H. Kizu, Y. Kameda,
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as stationary phase was packed into a glass column (160
2
0
0 mm) to a final bed volume of 50 mL. The flow rate was
À1
+
.9 mLmin . The CM-Shepharose-NH was washed initial-
4
ly with H O. Then, an aqueous solution of the crude materi-
2
al at pH 7 was loaded onto the column. Minor colored im-
purities were washed away with H O (150 mL, 3 bed vol-
umes). The retained compounds 8 and 9 were released with
[9] L. Chabaud, Y. Landais, P. Renaud, Org. Lett. 2005, 7,
2587–2590.
2
1
25 mL and 285 mL of aqueous 0.01M NH OH, respective-
[10] G. Dickson Lucas, E. Leroy, J.-L. Reymond, Org.
Biomol. Chem. 2004, 2, 1217–1226; A. Kato, N. Kato,
E. Kano, I. Adachi, K. Ikeda, L. Yu, T. Okamoto, Y.
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Chem. 2005, 48, 2036–2044; H. Ouchi, Y. Mihara, H.
4
ly. Pure fractions were pooled and lyophilized affording 8
(
20 mg) and 9 (26 mg). The operation was repeated until the
whole mixture was consumed.
A similar procedure was employed with the 7+9 mixture.
Adv. Synth. Catal. 2007, 349, 1661 – 1666
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1665