An efficient approach to the azaspirocyclic structure of halichlorine and pinnaic acid

Tetrahedron Letters

Volumn 40, Issue 45, 1999, Pages 7921-7924

  Lee, Sangku ^a   Zhao, Zuchun ^a  

^a BAYER AG   (Germany)

Author keywords

Cycloadditions; Natural products; Nitrogen heterocycles; Nitrones

Indexed keywords

1,3 DITHIANE DERIVATIVE; ALKALOID; AZASPIRO[4.5]DECANE; HALICHLORINE; PINNAIC ACID; UNCLASSIFIED DRUG;

ARTICLE; CYCLIZATION; HEAT; ISOMERISM; PARTIAL DRUG SYNTHESIS;

EID: 0033527604     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(99)01578-6     Document Type: Article

References (16)

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10. 3N), followed by the treatment with sodium iodide.
11. The stereochemisry of 15,17, 20 and 21 were confirmed by NOESY experiments.
12. 3: C, 66.85; H, 9.87; N, 5.49. Found: C, 65.58; H, 9.85; N, 5.25.
13. Our initial attempts to invert the configuration of 14 at C5, via a retro-Michael addition followed by an intramolecular Michael addition, using a variety of bases (NaH, KOBu-t, DBU, LiHMDS, NaHMDS) failed.
14. 3: C, 65.85; H, 9.87; N, 5.48. Found: C, 65.90; H, 9.90; N, 5.34.
15. 3: C, 65.85; H, 9.87; N, 5.49. Found: C, 65.69; H, 9.66; N, 5.61.
16. 3: C, 65.85; H, 9.87; N, 5.48. Found: C, 65.90; H, 9.66; N, 5.37.