| Autor: |
Mickel, S. J., Sedelmeier, G. H., Niederer, D., Schuerch, F., Seger, M., Schreiner, K., Daeffler, R., Osmani, A., Bixel, D., Loiseleur, O., Cercus, J., Stettler, H., Schaer, K., Gamboni, R., Bach, A., Chen, G.-P., Chen, W., Geng, P., Lee, G. T., Loeser, E., McKenna, J., Kinder, F. R., Jr., Konigsberger, K., Prasad, K., Ramsey, T. M., Reel, N., Repic, O., Rogers, L., Shieh, W.-C., Wang, R.-M., Waykole, L., Xue, S., Florence, G., Paterson, I. |
| Zdroj: |
Organic Process Research & Development; January 2004, Vol. 8 Issue: 1 p113-121, 9p |
| Abstrakt: |
Coupling of C9-14 (4) and C15-21 (5a) fragments to produce the cis-trisubstituted olefin was achieved using Suzuki-type coupling conditions employed by Marshall (5a/tert-BuLi/B-OMe-9-BBN added to 4/Cs2CO3/Pd(dppf)2). The terminal (Z)-diene moiety was attached to aldehyde 10 by using a sequential Nozaki−Hiyama allylation and Peterson olefination sequence; careful monitoring of the disappearance of both diastereomeric β-hydroxysilanes was found to be essential for achieving a high yield. In the oxidation of alcohols 12 and 16 to 13 and 7, respectively, using iodobenzene diacetate and TEMPO, addition of a trace of water was found to be crucial for complete conversion. The C8-9 (Z)-olefin functionality was introduced on to aldehyde 13 using a Still−Gennari HWE reaction. Subsequent carbamate installation at C-19 followed by a reduction/oxidation sequence gave the title fragment C7-24 (7) ready to be coupled with the C1-6 fragment, which is described in Part 2 of this series. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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