2.7- Dioxabicyclo heptane preparation

To add to the silver salt (Eq. 19) and peroxymercuration (Eq. 34-36) methods of preparing dialkyl peroxides, a third mild alkylation procedure has been developed that involves the use of alkyl trifluoromethane sulphonates (triflates)55). The peroxide transfer reaction between bistributyltin peroxide and the bistriflate 58 of cis-1,3-cyclopentanediol provided one of the first syntheses of 2,3-dioxabicyclo[2.2.1]heptane 9 (Eq. 44, H for D Tf = 02SCF3)56). Because of the sensitivity of 9, it was necessary to carry out the reaction in vacuo with rapid transfer of the volatile products to a cold trap to avoid decomposition a yield of 22% was achieved. 

Preparation of 2,7,8-trioxabicyclo[3.2.1]octanes by the oxidation of 2,7-dioxabicyclo[2.2.1]heptanes with m-chloroperbenzoic acid [189]. 

Finally, mention must be made of the efforts of R. G. Salomon s group to synthesize several derivatives of 2,3-dioxabicyclo[2.2.1]heptane, the strained bicyclic peroxide nucleus of prostaglandin endoperoxide (206). They are prepared from 2,3-dioxabicyclo[2.2.1]hept-5-ene by selective reduction with diimide or chlorination. 

Recently, other methods of endoperoxide synthesis have been reported that make the parent 2,3-dioxabicyclo[2.2.1]heptane system, readily available (25, 26, 27). For example, we have been able to prepare from 3-bromocyclopentanehydroperoxide. The trans bromohydroperoxide is converted to in 30 minutes by treatment with silver acetate. The cis bromohydroperoxide reacts much slower and leads to a mixture of products, including... 

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