Highly Selective Synthesis of Diepoxides from α,ω-Diiodoperfluoroalkanes

What is it about?

Synthesis of bis-adduct (III) is improved, i.e. lower yield of semi-rearranged by-product (IV) owing to lower reaction temperature and short reaction time. Since selectivity of direct epoxidation of bis-adduct (III) is extremely dependent on the solvent and in order to avoid formation of by-products (VI) and (VII), a two-step synthesis of diepoxide (V) via diiododiols (VIII) and (IX) is preferred. Ring opening of diepoxide (V) is achieved with complete regioselectivity by acid-catalyzed reactions, giving diol (XI) or tetrol (XIV), respectively. Base-catalyzed ring opening of (V) with methacrylic acid affords a mixture of regioisomers (XVI) and (XVII), whereas with morpholine diol (XIX) is obtained in complete regioselectivity. All reactions described here are also accomplished with the exaperfluoromethylene analogues (Y: -(CF2)6-) in (nearly) identical yields. Application of amphiphilic tetrol (XIV) or bis-methacrylates (XVI) and (XVII) (as mixture) for the preparation of new dendrimeric compounds or as crosslinking agents for polymers is of interest.

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Why is it important?

Synthesis of bis-adduct (III) is improved, i.e. lower yield of semi-rearranged by-product (IV) owing to lower reaction temperature and short reaction time. Since selectivity of direct epoxidation of bis-adduct (III) is extremely dependent on the solvent and in order to avoid formation of by-products (VI) and (VII), a two-step synthesis of diepoxide (V) via diiododiols (VIII) and (IX) is preferred. Ring opening of diepoxide (V) is achieved with complete regioselectivity by acid-catalyzed reactions, giving diol (XI) or tetrol (XIV), respectively. Base-catalyzed ring opening of (V) with methacrylic acid affords a mixture of regioisomers (XVI) and (XVII), whereas with morpholine diol (XIX) is obtained in complete regioselectivity. All reactions described here are also accomplished with the exaperfluoromethylene analogues (Y: -(CF2)6-) in (nearly) identical yields. Application of amphiphilic tetrol (XIV) or bis-methacrylates (XVI) and (XVII) (as mixture) for the preparation of new dendrimeric compounds or as crosslinking agents for polymers is of interest.

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