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.

烯烃的顺式双羟基化是有机合成中极具价值的反应。环酰过氧化物（cyclic acyl peroxides, CAPs）近来作为替代此类反应中常用有毒金属的极具潜力候选试剂而崭露头角。本研究证明，结构复杂的环过氧化物螺[双环[2.2.1]庚烷-2,4′-[1,2]二氧戊环]-3′,5′-二酮（P4）可有效用于烯烃的顺式双羟基化反应。与其他CAPs相比，试剂P4对带有β-氢的烯烃的双羟基化反应展现出更优的选择性——其他CAPs体系中二醇与烯丙醇产物会相互竞争。此外，使用对映纯的P4（标记为P4′）的实验证明，P4′可用于实现无金属的烯烃不对称顺式双羟基化反应。