A New [5+2] Annulation Method for the Synthesis of 8-Oxabicyclo[3.2.1]octanes from Pyrones

Synlett

Volumn 1997, Issue 1, 1997, Pages 81-82

  Mascareñas, José L ^a   Pérez, Ignacio ^a   Rumbo, Antonio ^a   Castedo, Luis ^a  

^a UNIVERSITY OF SANTIAGO DE COMPOSTELA   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 1542682093     PISSN: 09365214     EISSN: None     Source Type: Journal    
DOI: 10.1055/s-1997-698     Document Type: Article

References (22)

1. This paper is dedicated to the memory of Prof. Ignacio Ribas, recently deceased.
2. Rumbo, A.; Castedo, L.; Mouriño, A.; Mascareñas, J. L. J. Org. Chem. 1993, 58, 5585.
3. These cycloadducts can be broken down into sesquiterpene precursors or stereochemically rich 2,3,5-trisubstituted tetrahydrofuranes: Rumbo, A.; Castedo, L.; Mouriño, A.; Mascareñas, J. L. unpublished results.
4. A method based on the conversion of the pyrone into highly reactive 4-methoxy-3-oxidopyrilium ylides has recently been described: (a) Wender, P. A.; Mascareñas, J. L. J. Org. Chem. 1991, 56, 6267. (b) Wender, P. A.; Mascareñas, J. L. Tetrahedron Lett. 1992, 33, 2115.
5. A method based on the conversion of the pyrone into highly reactive 4-methoxy-3-oxidopyrilium ylides has recently been described: (a) Wender, P. A.; Mascareñas, J. L. J. Org. Chem. 1991, 56, 6267. (b) Wender, P. A.; Mascareñas, J. L. Tetrahedron Lett. 1992, 33, 2115.
6. Garst, M. E.; McBride, B. J.; Douglass, J. G. Tetrahedron Lett. 1983, 24, 1675.
7. 2).
8. 1H NMR spectra of crude reaction samples revealed a considerable downfield shift of the pyrone protons and a typical methoxy group signal at δ 4.46 ppm.
9. This compound was synthesized following recently described procedures: Rumbo, A.; Castedo, L.; Mouriño, A.; Mascareñas, J. L. J. Org. Chem. 1996, 61, 6114.
10. 2).
11. 1H NMR, that shows a methoxy group signal at δ = 4.45 ppm, and two singlets at 8.06 and 8.45 ppm.
12. 3): δ = 1.94 (dd, 1H, J = 12.5 and 9.5 Hz), 2.18-2.26 (m, 1H), 2.76-2.83 (m, 1H), 3.58 (t, 1H, J = 9.2 Hz), 3.63 (s, 3H), 4.01 (d, 1H, J = 9.5 Hz), 4.16-4.22 (m, 2H), 4.84 (d, 1H, J = 8 Hz), 6.12 (s, 1H).
13. 3).
14. Wender, P. A.; Miller, B. L. in Organic Synthesis: Theory and Applications Hudlicky, T. Ed.; Jai Press, 1993; Vol 2, pp 27-66.
15. Engler, T. A.; Combrink, K. D.; Letavic, M. A.; Lynch, K. O.; Ray, J. E. J. Org. Chem. 1994, 59, 6567.
16. Allyltriisopropylsilane was chosen with the aim of evaluating the feasibility of a Wagner-Meervein type of rearrangement in our reaction system: (a) Danheiser, R. L.; Dixon, B. R.; Gleason, W. G. J. Org. Chem. 1992, 57, 6094. (b) Knolker, H. -J.; Foitzik, N.; Goesman, H.; Graf, R. Angew. Chem. Int. Ed. Engl. 1993, 32, 1081.
17. Allyltriisopropylsilane was chosen with the aim of evaluating the feasibility of a Wagner-Meervein type of rearrangement in our reaction system: (a) Danheiser, R. L.; Dixon, B. R.; Gleason, W. G. J. Org. Chem. 1992, 57, 6094. (b) Knolker, H. -J.; Foitzik, N.; Goesman, H.; Graf, R. Angew. Chem. Int. Ed. Engl. 1993, 32, 1081.
18. 2), 11.1 (CH).
19. For [4C+3C] cycloadditions, see: (a) Hosomi, A.; Tominaga, Y. in Comprehensive Organic Synthesis, Trost, B. M.; Fleming, I. A. Eds; Pergamon: New York, 1991; Vol 5, chapter 5.1. (b) Harmata, M. In Advances in Cycloaddition; Lautens, M. Ed.; JAI: Greenwich, 1995; Vol 4. For [5C+2C] annulations, see: (c) Sammes, P. G. Gazz. Chim. Ital. 1986, 119, 109. (b) Padwa, A.; Fryxell, G. E.; Zhi., H. J. Am. Chem. Soc. 1990, 112, 3100.
20. For [4C+3C] cycloadditions, see: (a) Hosomi, A.; Tominaga, Y. in Comprehensive Organic Synthesis, Trost, B. M.; Fleming, I. A. Eds; Pergamon: New York, 1991; Vol 5, chapter 5.1. (b) Harmata, M. In Advances in Cycloaddition; Lautens, M. Ed.; JAI: Greenwich, 1995; Vol 4. For [5C+2C] annulations, see: (c) Sammes, P. G. Gazz. Chim. Ital. 1986, 119, 109. (b) Padwa, A.; Fryxell, G. E.; Zhi., H. J. Am. Chem. Soc. 1990, 112, 3100.
21. For [4C+3C] cycloadditions, see: (a) Hosomi, A.; Tominaga, Y. in Comprehensive Organic Synthesis, Trost, B. M.; Fleming, I. A. Eds; Pergamon: New York, 1991; Vol 5, chapter 5.1. (b) Harmata, M. In Advances in Cycloaddition; Lautens, M. Ed.; JAI: Greenwich, 1995; Vol 4. For [5C+2C] annulations, see: (c) Sammes, P. G. Gazz. Chim. Ital. 1986, 119, 109. (b) Padwa, A.; Fryxell, G. E.; Zhi., H. J. Am. Chem. Soc. 1990, 112, 3100.
22. For [4C+3C] cycloadditions, see: (a) Hosomi, A.; Tominaga, Y. in Comprehensive Organic Synthesis, Trost, B. M.; Fleming, I. A. Eds; Pergamon: New York, 1991; Vol 5, chapter 5.1. (b) Harmata, M. In Advances in Cycloaddition; Lautens, M. Ed.; JAI: Greenwich, 1995; Vol 4. For [5C+2C] annulations, see: (c) Sammes, P. G. Gazz. Chim. Ital. 1986, 119, 109. (b) Padwa, A.; Fryxell, G. E.; Zhi., H. J. Am. Chem. Soc. 1990, 112, 3100.