Remarkable Influence of Cobalt Catalysis on Epoxide Ring-Opening with Sulfoxonium Ylides.

Cobalt demonstrates a remarkable ability to catalytically divert the course of epoxide to oxetane ring expansion via reaction with a sulfoxonium ylide. An expanded survey of transition-metal catalysts has confirmed that cobalt salts uniquely instead deliver homoallylic alcohol products from epoxides, with retention of the original epoxide stereochemistry. The reaction is an unusual example of cobalt-catalysed epoxide ring-opening by a carbon nucleophile. A tandem Corey-Chaykovsky/epoxide olefination sequence giving homoallylic alcohols from aldehydes is further demonstrated along with preliminary mechanistic analysis. This communication summarises current understanding and ongoing studies into this intriguing new cobalt-mediated reactivity. [ABSTRACT FROM AUTHOR]