TOWARDS OLEANANES - GEMINAL DIMETHYLATION AT C-4

[摘要] A model of the ABC rings of the oleananes, prepared by biomimetic polyene cyclization, shows that the system is sufficiently rigid to prevent epimerization of the C-5 hydrogen with a ketone functionality in place at C-4. Such a sterically hindered ketone has been successfully transformed to a geminal dimethyl group by a three-step procedure.

[发布日期] 1994-12-26