| Autor: |
Back, Thomas G., Blazecka, Peter G., Krishna, M. Vijaya |
| Zdroj: |
Canadian Journal of Chemistry; February 1993, Vol. 71 Issue: 2 p156-163, 8p |
| Abstrakt: |
Brassinolide (1) and castasterone (2) were prepared from aldehyde 7, in turn available from stigmasterol (3). The addition of (E)-1-propenyllithium to 7, followed by diastereoselective Sharpless epoxidation of allylic alcohol 8using (L)-(+)-diethyl tartrate, and regioselective epoxide-opening of (threo) epoxy alcohol 15with isopropylmagnesium chloride in the presence of a catalytic amount of cuprous cyanide afforded diol 17. The epoxidation and cuprate addition steps were investigated in greater detail with the simpler model aldehyde 4. Hydrolysis of 17provided 2, which was converted preferentially into 1or its regioisomer 22by Baeyer–Villiger oxidation with trifluoroperoxyacetic acid or peroxyseleninic acids, respectively. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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