Epoxide-furanoid rearrangement

Surprisingly, the 2,3-epoxide ring of pyranoid or furanoid derivatives proved to be highly unreactive toward carbonyl insertion reactions or in rearrangement to ketoses, either when catalyzed by hydrogen cobalt tetracarbonyl or sodium cobalt tetracarbonyl. When moisture was not carefully excluded, preferential hydrolysis of the epoxide ring occurred to afford the diaxial product. 

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