Popis: |
The 1,2-hydroxy hydroperoxide 7 was obtained with high threo diastereoselectivity from the ester-conjugated allylic alcohol 6 through a porphyrin-sensitized singlet oxygen ene reaction. Compound 7 was used as substrate for peroxy(trans)acetalization with aldehydes, orthoesters, and acetals, catalyzed by boron and indium Lewis acids, as well as by PPTS as a Bronsted acid catalyst (for trioxane 10). The 1,2,4-trioxane 8 was formed with high diasteroselectivity with all-equatorially positioned substitutents at C-3, C-5, and C-6. Additionally, perorthoester 9 was obtained by indium(III)-catalyzed condensation of an orthoester with the hydroperoxide 7. The new compounds 8 and 9 exhibited moderate inhibition of human placental glutathione transferase (GST), comparable to that shown by the 5-unsubstituted model trioxane 11. |