Bridged bicyclic endoperoxides, synthesis

More recently, Bachi and coworkers extended and adapted the TOCO reaction to the synthesis of 2,3-dioxabicyclo[3.3.1]nonane derivatives hke 228 (Scheme 52) ° ° . As detailed in Scheme 53a, the bridged bicyclic hydroperoxide-endoperoxides hke 229 are obtained, from (S )-limonene (227), in a 4-component one-operation free-radical domino reaction in which 5 new bonds are sequentially formed. Particular experimental conditions are required in order to reduce the formation of by-products 230 and (PhS)2, and to favor the critical 6-exo-ring closure of peroxy-radical 231 to carbon-centered radical 232206 chemoselective reduction of bridged bicyclic hydroperoxide-endoperoxides... 

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