In four or five chemical steps from the 1,2,4-trioxane artemisinin, a new series of 23 trioxane dimers has been prepared. Eleven of these new trioxane dimers cure malaria-infected mice via oral dosing at 3 x 30 mg/kg. The clinically used trioxane drug sodium artesunate prolonged mouse average survival to 7.2 days with this oral dose regimen. In comparison, animals receiving no drug die typically on day 6-7 postinfection. At only 3 x 10 mg/kg oral dosing, seven dimers prolong the lifetime of malaria-infected mice to days 14-17, more than double the chemotherapeutic effect of sodium artesunate. Ten new trioxane dimers at only a single oral dose of 30 mg/kg prolong mouse average survival to days 8.7-13.7, and this effect is comparable to that of the fully synthetic trioxolane drug development candidate OZ277, which is in phase II clinical trials.
A full account of our synthetic work toward the first total synthesis of the neuroactive marine macrolide (-)-palmyrolide A is described. Our first-generation approach aimed to unlock the unknown C(5)-C(7) stereochemical relationship via the synthesis of four diastereomers of palmyrolide A aldehyde, a known degradation product. When these efforts provided inconclusive results, recourse to synthesizing all possible stereocombinations of the 15-membered macrolide was undertaken. These studies were critical in confirming the absolute stereochemistry, yielding the first total synthesis of (+)-ent-palmyrolide A. Subsequent to this work, the first protecting-group-free total synthesis of natural (-)-palmyrolide A is also reported.
Distinctly different: Two 1‐oxa‐2‐silacyclopentenes and a saturated congener have been synthesized and demonstrated to provide access to type II anion relay chemistry (ARC) through a fundamentally new mechanistic pathway. Similar to previous studies, but contrary to initial hypothesis, Brook rearrangement additives (hexamethylphosphoramide and CuI) are necessary to promote Si migration and anion capture.
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