| Autor: |
Eggen M; Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66045, USA., Mossman CJ, Buck SB, Nair SK, Bhat L, Ali SM, Reiff EA, Boge TC, Georg GI |
| Jazyk: |
angličtina |
| Zdroj: |
The Journal of organic chemistry [J Org Chem] 2000 Nov 17; Vol. 65 (23), pp. 7792-9. |
| DOI: |
10.1021/jo000767+ |
| Abstrakt: |
Two efficient protocols for the synthesis of tert-butyl (5S,6R,2E, 7E)-5-[(tert-butyldimethylsilyl)oxy]-6-methyl-8-phenyl-2, 7-octadienoate, a major component of the cryptophycins, are reported. The first utilized the Noyori reduction and Frater alkylation of methyl 5-benzyloxy-3-oxopentanoate to set two stereogenic centers, which became the C16 hydroxyl and C1' methyl of the cryptophycins. The second approach started from 3-p-methoxybenzyloxypropanal and a crotyl borane reagent derived from (-)-alpha-pinene to set both stereocenters in a single step and provided the dephenyl analogue, tert-butyl (5S,6R,2E)-5-[(tert-butyldimethylsilyl)oxy]-6-methyl-2, 7-octadienoate, in five steps. This compound was readily converted to the 8-phenyl compound via Heck coupling. The silanyloxy esters were efficiently deprotected and coupled to the C2-C10 amino acid fragment to provide desepoxyarenastatin A and its dephenyl analogue. The terminal olefin of the latter was further elaborated via Heck coupling. Epoxidation provided cryptophycin-24 (arenastatin A). |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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