RESUMO
Cycloalkanones were utilized in the Lewis acid catalyzed peroxyacetalization of ss-hydroperoxy homoallylic alcohols (prepared by the ene reaction of the allylic alcohols mesitylol and methyl 4-hydroxytiglate, respectively, with singlet oxygen) to give spiroannulated 1,2,4-trioxanes 5a-5e and 9a-9e, respectively. A second series of 3-arylated trioxanes 10a-10h, that are available from the hydroperoxy alcohol 4 and benzaldehyde derivatives, was investigated by X-ray crystallography.
RESUMO
A set of new bis-spirofused 1,2,4-trioxanes 4a-d was obtained from the reaction of cyclohexane-1,4-dione with allylic hydroperoxides 2a-d, bearing an additional hydroxy group in the homoallylic position, by diastereoselective photooxygenation of allylic alcohols 1a-d and subsequent BF(3)-catalyzed peroxyacetalization with the diketone. From the reaction of a monoprotected cyclohexane-1,4-dione 5 with the allylic hydroperoxide 6 derived from the singlet oxygenation of methyl hydroxytiglate, one monospiro compound was obtained, the 1,2,4-trioxane ketone 7, as well as a mixture of the diastereoisomeric syn- and anti bis-1,2,4-trioxanes 8. The structures of bis-1,2,4-trioxanes were examined theoretically by DFT methods and compared with X-ray structural data in order to evaluate the preferential trioxane ring conformational orientation.
Assuntos
Peróxidos/síntese química , Compostos de Espiro/síntese química , Cicloexanos/química , Compostos Heterocíclicos/síntese química , Compostos Heterocíclicos/química , Peróxido de Hidrogênio/química , Estrutura Molecular , Peróxidos/química , Compostos de Espiro/químicaRESUMO
A remarkable increase in antimalarial in vitro activity was achieved by integration of spiroadamantane motifs in 6-alkylidene 1,2,4-trioxanes 3a-h via diastereoselective photooxygenation of allylic alcohols and subsequent BF(3)-catalyzed peroxyacetalization with adamantanone to give the active compounds 3e-h.