ꢀ
S. Rodrıguez et al. / Tetrahedron Letters 45 (2004) 5359–5361
5361
5. For stereoselective Michael reactions of c-alkoxy a,b-
unsaturated esters see: (i) Yamamoto, Y.; Chounan, Y.;
Nishii, S.; Ibuka, T.; Kitahara, H. J. Am. Chem. Soc. 1992,
114, 7652–7660; (ii) Asao, N.; Shimada, T.; Sudo, T.;
Tsukada, N.; Yazawa, K.; Gyoung, Y. S.; Uyehara, T.;
Yamamoto, Y. J. Org. Chem. 1997, 62, 6274–6282.
6. Although the reactions in Scheme 2 appear in the
literature, they have been optimised so as to provide an
efficient way of making aldehyde 5.
Acknowledgements
This work was financed by Conselleria d’Educacio,
ꢀ
ꢁ
i Ciencia de la Generalitat Valenciana
Cultura
(CTIDIA/2002/124) and Bancaixa-UJI foundation (PI-
1B2002-06). We thank Serveis Centrals d’Instrumen-
ꢀ
ꢀ
tacio Cientıfica de la Universitat Jaume I for technical
support and especially Prof. William R. Roush for
helpful discussions.
7. White, J. D.; Carter, J. P.; Kezar, H. S., III. J. Org. Chem.
1982, 47, 929–932.
8. Meyers, A. I.; Nolen, R. L.; Collington, E. W.; Narwid, T.
A.; Strickland, R. C. J. Org. Chem. 1973, 38, 1974–1982.
9. Distillation over potassium bisulfate of the crude is
necessary to convert a nondesired product resulting from
ethanol incorporation into the desired alkene 4:
References and notes
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Lett. 1987, 28, 4435–4436; (ii) Saito, S.; Takahashi, N.;
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667–670; (iii) Lanier, M.; Pastor, R. Tetrahedron Lett.
1995, 36, 2491–2492; (iv) Righi, G.; Rumboldt, G. J. Org.
O
O
KHSO4
EtO
EtO
OEt
OEt
OEt
OEt OEt
4
ꢀ
~
See: Farina, F.; Victory, P. Tetrahedron Lett. 1969, 38,
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Chem. 1996, 61, 3557–3560; (v) Concellon, J. M.; Bar-
dales, E. Org. Lett. 2002, 4, 189–191; (vi) Tosaki, S.;
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5, 495–498; (vii) Concellon, J. M.; Bardales, E.; Llavona,
R. J. Org. Chem. 2003, 68, 1585–1588.
10. Coppola, G. M. Synthesis 1984, 1021–1023.
11. When we used n-BuLi partial transesterification of the
epoxy ethyl ester was observed, this must be due to the
formation of n-BuOLi from oxidation of n-BuLi by TBPLi
(see: Boche, G.; Mbus, K.; Harms, K.; Lohrenz, J. C. W.;
Marsch, M. Chem. Eur. J. 1996, 2, 604–607) or probably
already present in the n-BuLi. If EtLi is used, the ester is
not affected.
ꢀ
2. Fernandez de la Pradilla, R.; Marıa Victoria Buergo, M.
V.; Manzano, P.; Montero, C.; Priego, J.; Viso, A.; Cano,
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F. H.; Martınez-Alcazar, M. P. J. Org. Chem. 2003, 61,
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3. (i) Jackson, R. F. W.; Standen, S. P.; Clegg, W.;
McCamley, A. J. Chem. Soc., Perkin Trans. 1 1995, 149–
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Chem. Soc., Perkin Trans. 1 1995, 141–148.
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15.
13. Modelling of the lactones give as the closest distance
ꢂ
between the methyl and H-1: 3 A for syn–anti lactone
ꢂ
(possible NOE) and 4.2 A for the syn–syn one (no possible
NOE).