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C. Bolm et al.
LETTER
(6) Shimizu, M.; Matsukawa, K.; Fujisawa, T. Bull Chem. Soc.
Jpn. 1993, 66, 2128-2130.
(7) (a) Seebach, D.; Jaeschke, G.; Wang, Y. M. Angew. Chem.
1995, 107, 2605-2606; Angew. Chem., Int. Ed. Engl. 1995, 34,
2395-2396. (b) Jaeschke, G.; Seebach, D. J. Org. Chem. 1998,
63, 1190-1197. (c) Seebach, D.; Jaeschke, G.; Gottwald, K.;
Matsuda, K.; Formisano, R.; Chaplin, D. A.; Breuning, M.;
Bringmann, G. Tetrahedron 1997, 53, 7539-7556.
(8) When more hindered alcohols such as ethanol or 2-propanol
were used as nucleophiles decreased reaction rates and lower
enantioselectivities were observed. Primary and secondary
amines as well as thiols also gave less satisfactory results.
(9) Representative procedure: Methanol (0.122 mL, 3.0 mmol)
was added dropwise to a stirred suspension of cis-endo-bi-
cyclo[2.2.1]-hept-5-ene-2,3-dicarboxylic anhydride (1)
(0.164 g, 1.0 mmol) and quinidine (0.357 g, 1.1 mmol) in to-
luene (2.5 mL) and tetrachloromethane (2.5 mL) at -50 °C un-
der argon. The reaction mixture was stirred at that temperature
for 36 h. During this period it gradually changed from hetero-
geneous to homogeneous. Subsequently, the resulting clear
solution was concentrated in vacuo to dryness, then the resul-
ting residue was dissolved in ethyl acetate (40 mL). The solu-
tion was washed with 2 N HCl (2 x 4 mL) and after phase
separation the organic layer was dried over MgSO4, filtered,
and concentrated providing 0.163 g (83 %) of (2R,3S)-(+)-cis-
endo-3-methoxycarbonyl-bicyclo[2.2.1]hept-5-ene-2-car-
boxylic acid (2) as a white solid {purity > 98 % (NMR, GC-
MS), mp 75-78 °C (Lit.:10 76-78.5 °C), [α]D20 = + 7.7 (CCl4,
c = 4.23) (Lit.:11 + 7.9, c = 4.8), 98% ee [HPLC-analysis
of the methyl-4-bromophenyl diester: Chiralcel OD-H
at rt, 2% 2-propanol/n-heptane, 0.5 mL/min, 254 nm, tR
= 20.27 min (2S,3R)-(-) and 23.15 min (2R,3S)-(+)}.
The absolute configuration was determined by selective
reduction of the methylester group with LiBEt3H follo-
wed by catalyzed lactonization providing a known lac-
tone.11 The alkaloid was quantitatively recovered by
neutalization of the aqueous layer with NaHCO3 and ex-
traction with ethyl acetate.
Acknowledgment
This work was partially supported by the BMBF, and we are grate-
ful to the Fonds der Chemischen Industrie for financial help.
References and Notes
(1) Part of the dissertation of A. G. (RWTH Aachen 1998).
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165-261 and references cited therein.
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1987, 1100-1103.
(5) (a) Albers, T.; Biagini, S. C. G.; Hibbs, D. E.; Hursthouse, M.
B.; Malik, K. M. A.; North, M.; Uriarte, E.; Zagotto, G. Syn-
thesis 1996, 393-398. (b) Ward, R. S.; Pelter, A.; Edwards, M.
I.; Gilmore, J. Tetrahedron: Asymmetry 1995, 6, 843-844.
(c) Kawakami, Y.; Hiratake, J.; Yamamoto, Y.; Oda, J. J.
Chem. Soc., Chem. Commun. 1984, 779-781.
(10) Morgan, M. S.; Tipson, R. S.; Lowy, A.; Baldwin, W.E. J. Am.
Chem. Soc 1944, 66, 404-407.
(11) Storme, P.; Quaeghebeur, L.; Vandewalle, M. Bull. Soc.
Chim. Belg. 1984, 93, 999-1003.
(12) Reichardt, C.; Solvents and Solvent Effects in Organic Chemi-
stry; 2nd ed.; VCH; Weinheim; 1990; pp.407-411.
(13) Bolm, C.; Gerlach, A.; Dinter, C.; Schiffers, I. to be published.
Synlett 1999, No. 2, 195–196 ISSN 0936-5214 © Thieme Stuttgart · New York