sirolimus has been researched along with titanium-isopropoxide* in 1 studies
1 other study(ies) available for sirolimus and titanium-isopropoxide
| Article | Year |
|---|---|
Selective epimerization of rapamycin via a retroaldol/aldol mechanism mediated by titanium tetraisopropoxide.
We describe the efficient and selective epimerization of the immunosuppressant rapamycin to 28-epirapamycin under mild conditions. The mechanism of epimerization involves an equilibrium of the four C28/C29 diastereomers through a two-step retroaldol/aldol (macrocycle ring-opening/ring-closing) sequence. This retroaldol/aldol equilibration is not restricted to rapamycin but is also applicable to acyclic beta-hydroxyketones. A potentially useful extension of the method--the use of beta-hydroxyketones as enolate synthons for effecting inter- or intramolecular aldol reactions under neutral conditions--is demonstrated. Topics: Anti-Bacterial Agents; Catalysis; Immunosuppressive Agents; Organometallic Compounds; Sirolimus; Stereoisomerism; Titanium | 1999 |