Syn-Dihydroxylation of Alkenes Using a Sterically Demanding Cyclic Diacyl Peroxide.

The syn-dihydroxylation of alkenes is a highly valuable reaction in organic synthesis. Cyclic acyl peroxides (CAPs) have emerged recently as promising candidates to replace the commonly employed toxic metals for this purpose. Here, we demonstrate that the structurally demanding cyclic peroxide spiro[bicyclo[2.2.1]heptane-2,4'-[1,2]dioxolane]-3',5'-dione (P4) can be effectively used for the syn-dihydroxylation of alkenes. Reagent P4 also shows an improved selectivity for dihydroxylation of alkenes bearing β-hydrogens as compared to other CAPs, where both diol and allyl alcohol products compete with each other. Furthermore, the use of enantiopure P4 (labeled P4') demonstrates the potential of P4' for a metal-free asymmetric syn-dihydroxylation of alkenes.