Synthetic Studies of Mniopetals. Intramolecular Diels-Alder Cycloaddition Approach for Access to a Key Tricyclic Driman-type Intermediate

Synlett

Volumn 1997, Issue 11, 1997, Pages 1291-1293

  Murata, Takeshi ^a   Ishikawa, Makoto ^a   Nishimaki, Ryoko ^a   Tadano, Kin Ichi ^a  

^a KEIO UNIVERSITY   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0002562789     PISSN: 09365214     EISSN: None     Source Type: Journal    
DOI: 10.1055/s-1997-5796     Document Type: Article

References (18)

1. Kuschel, A.; Anke, T.; Velten, R.; Klostermeyer, D.; Steglich, W.; König, B. J. Antibiot. 1994, 47, 733.
2. Velten, R.; Klostermeyer, D.; Steffan, B.; Steglich, W.; Kuschel, A.; Anke, T. J. Antibiot. 1994, 47, 1017.
3. Ayer, W. A.; Craw, P. A. Can. J. Chem. 1989, 67, 1371.
4. Velten, R.; Steglich, W.; Anke, T. Tetrahedron: Asymmetry 1994, 5, 1229.
5. A leading review on the IMDA cycloadditions, see: Roush, W. R. In Comprehensive Organic Synthesis; Trost, B. M.; Fleming, I.; Paquette, L. A. Eds.; Pergamon; Oxford, 1991, Vol. 5, p. 513.
6. Previous publications from our laboratories on the IMDA cycloaddition approach for natural products synthesis, see: Tadano, K.; Murata, T.; Kumagai, T.; Ogawa, S. Tetrahedron Lett. 1993, 34, 7279; Murata, T.; Kumagai, T.; Ishikawa, M.; Tadano, K.; Ogawa, S. Bull. Chem. Soc. Jpn. 1996, 69, 3551.
7. Previous publications from our laboratories on the IMDA cycloaddition approach for natural products synthesis, see: Tadano, K.; Murata, T.; Kumagai, T.; Ogawa, S. Tetrahedron Lett. 1993, 34, 7279; Murata, T.; Kumagai, T.; Ishikawa, M.; Tadano, K.; Ogawa, S. Bull. Chem. Soc. Jpn. 1996, 69, 3551.
8. Katsuki, T.; Lee, A. W. M.; Ma, P.; Martin, V. S.; Masamune, S.; Sharpless, K. B. Tuddenham, D.; Walker, F. J. J. Org. Chem. 1982, 47, 1373.
9. 13C (67.5 MHz) NMR, IR], and gave satisfactory HRMS except aldehydic and some unstable intermediates (11, 16, 19, 24-26). Yields refer to homogeneous samples purified by chromatography on silica gel.
10. Muncuso, A. J; Huang, S. L.; Swern, D. J. Org. Chem. 1978, 43, 2480.
11. 2O.
12. We examined direct introduction of the isobutylate unit by the alkylation of the respective tosylate, iodide, or triflate derived from 10 with the enolate generated from methyl isobutylate (LDA). However, the substrates (the tosylate and iodide) were recovered intact or the triflate decomposed.
13. We examined the Horner-Emmons olefmation of 16 with triethyl 4-phosphonocrotonate (LHMDS as a base) for direct introduction of the dienoate unit. The yield of 20 was 31% and ratio of the geometric isomers was ca. 8:1.
14. Ishihara, K.; Kurihara, H.; Yamamoto, H. J. Org. Chem. 1993, 58, 3791.
15. We examined other oxidation conditions (PCC, Swern), however, the yield of 25 was less useful in both cases.
16. Blanchette, M. A.; Choy, W.; Davis, J. T.; Essenfeld, A. P.; Masamune, S.; Roush, W. R.; Sakai, T. Tetrahedron Lett. 1984, 25, 2183.
17. On the other hand, we extensively explored on the construction of the butenolide unit by means of intermolecular aldol, Wittig or Horner-Emmons reaction approach from 22. None of the approaches examined provided useful results.
18. We also synthesized another substrate (not shown) for the IMDA cycloaddition, in which each OMM group in 27 was replaced by a pivaloyl ester. Under analogous thermal IMDA cycloaddition conditions used for 27, two endo-adducts were obtained from the pivaloyl ester substrate in 49% and 27% yields, respectively. The replacement of the substituents with more sterically demanding groups did not effect significantly on stereochemical bias of the π-facial selectivity. It should be also emphasized that the 1,3-diaxial repulsions in the TSs are one of the stereodirecting factors but not the exclusive one.