Stereoselective synthesis of flavonoids. Part 7. Poly-oxygenated β-hydroxydihydrochalcone derivatives
✍ Scribed by Reinier J.J. Nel; Hendrik van Rensburg; Pieter S. van Heerden; Johan Coetzee; Daneel Ferreira
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- French
- Weight
- 513 KB
- Volume
- 55
- Category
- Article
- ISSN
- 0040-4020
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Epoxidation of a series of poly--oxygenated chalcones with urea-hydrogen peroxide complex in THF in the presence of DBU and poly-(L)-or -(D)-leucine, followed by TBTH/AIBN catalysed ringopening, afforded I~-hydroxydihydrochalcones in moderate to high enantiomeric excess and yield.
Enantioselective Synthesis of Flavonoids. Part 5. Poly-Oxygenated β-Hydroxydihydrochalcones. -Epoxidation of enones (I) with urea hydrogen peroxide complex in the presence of poly-(L)-leucine leads to formation of the corresponding epoxides (II) with good levels of enantioselectivity. The following
Treatment of 3~.benzoyloxy-140, 15wepoxy-5(~.cholesg-7-ene with boron trifluoride-etherate 8ave, in 43% yield, 30-benzoyloxy-Sa, 14~cholest-7-en,15-one with the unnatt~ral C-D ring juncture, Reduction of the latteg compound with lithium aluminum hydride gave 15a, 14O-~holest-7.en'3p, 15wdiol and 5~,