Total synthesis of guanacastepene A: A route to enantiomeric control Journal Article
| Authors: | Mandal, M.; Yun, H.; Dudley, G. B.; Lin, S.; Tan, D. S.; Danishefsky, S. J. |
| Article Title: | Total synthesis of guanacastepene A: A route to enantiomeric control |
| Abstract: | The goal of the total synthesis of guanacastepene A served as a focus to bring together several chemical inquiries. One involved the synthesis of fused 5,7-hydrazulenones (see structure 20). Another issue had to do with the mechanistic intermediates in reductive cyclizations (see 17 to 18 and 19). The total synthesis required a mastery of an intramolecular Knoevenagel condensation of a β,γ-unsaturated ketone (see compound 41). Actually, cyclization was best accomplished when the terminal double bond of 41 was first converted to an epoxide. Further issues related to the stereochemistry at C5 and, rather surprisingly, the propensity for β-face acetoxylation at C 13. Crystallographic verification of the assigned β-stereochemistry at C13 is provided. Finally, a route to optically active material is provided (see compound 20). A key element in this construction was an enantioselective addition of isopropenyl cuprate to 2-methylcyclopentenone (see compound 99). © 2005 American Chemical Society. |
| Keywords: | unclassified drug; magnetic resonance spectroscopy; amino acids; cyclization; reaction analysis; synthesis; synthesis (chemical); stereochemistry; stereoisomerism; ketone; ketones; chemical bond; carbon; chemical modification; condensation; reduction; crystallography; diterpenes; enantiomer; enantioselectivity; nitrogen compounds; chemical bonds; diterpenoid; epoxide; copper derivative; spectrometry, mass, electrospray ionization; enantiomers; propensity; intramolecular bonds; unsaturated ketones; 2 methylcyclopentenone; 5,7 hydrazulenone derivative; azulene derivative; cyclopentenone derivative; fused alicyclic compound; guanacastepene a; isoprenyl cuprate; acetoxylation; knoevenagel condensation; optical rotation |
| Journal Title: | Journal of Organic Chemistry |
| Volume: | 70 |
| Issue: | 26 |
| ISSN: | 0022-3263 |
| Publisher: | American Chemical Society |
| Date Published: | 2005-12-23 |
| Start Page: | 10619 |
| End Page: | 10637 |
| Language: | English |
| DOI: | 10.1021/jo051470k |
| PUBMED: | 16355979 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | --- - "Cited By (since 1996): 28" - "Export Date: 24 October 2012" - "CODEN: JOCEA" - "Source: Scopus" |
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539Danishefsky
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