Hydroperoxides cyclic, ring opening

Free radical polymerization of cyclic ketene acetals has been used for the synthesis of polyfy-butyrolactone), which cannot be prepared by the usual lactone route due to the stability of the five-membered ring. The polymerization of 2-methylene-l,3-dioxalane at high temperatures (above 120 °C) gave a high molecular mass polyester [59,79]. Only 50% of the rings opened when the polymerization was carried out at 60 °C, and this led to the formation of a random copolymer. The presence of methyl substituents at the 4- or 5-position facilitated the reaction. The free radical initiators generally used in such polymerizations are ferf-butyl hydroperoxide, ferf-butyl peroxide, or cumene hydroperoxide. The various steps involved are described in Scheme 5 [59]. 

Hydroperoxides have been cyclized onto a, (3-unsaturated esters to furnish eventually syn-tetrahydrofurans possessing the necessary functionalization for elaboration into polyether type structures Initial 1,4-attack of the hydroperoxide onto the unsaturated ester gives a six-membered cyclic peroxide which then undergoes anion-promoted ring opening producing an epoxide which is in turn... 

Ferrous sulfate/cupric sulfate Oxidation of free radicals as a preparative method Ring opening of cyclic hydroperoxides... 

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