Epoxides opening with oxygen nucleophiles

The primary type of epoxide reaction remains the nucleophilic ring-opening reaction. The ring opening reactions of epoxides with oxygen nucleophiles represents an important method for the synthesis of differentially O-substituted 1,2-diols. The ring opening of epoxides with... 

The chemistry of epoxides is dominated by the basicity of the oxygen lone pairs and the release of ring strain as the three-membered ring opens. Many of the reactions of epoxides are acid or Lewis acid catalysed. The catalyst may coordinate with the oxygen, increasing the polarity of the C -O bond and the sensitivity of the carbon atom to reaction with a nucleophile. The reactivity of epoxides are summarized in Box 2.5. 

The 5 y -opening of epoxides is a challenging reaction pathway to access. The use of arylborates, 122, may provide a general non-catalyzed route to such a reaction manifold <05CC1426>. Treatment of epoxide 121 with borate 122 provides 123 in 63% yield. The reaction occurs through an initial activation of the epoxide with the boron followed by syn-nucleophilic attack of the phenolic oxygen. This reaction occurs with some A-Boc aziridines as well although both syn and anfi-opened products are obtained. 

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