Cyclopropanols are versatile synthetic intermediates that undergo regioselective ring-opening reactions.  Previous research in our group led to the development of a selective, iridium-catalyzed, cyclopropanol ring-opening isomerization to access unsymmetrical a-methyl ketones.  In an attempt to introduce groups other than methyl to the a position, we sought to develop a palladium-catalyzed oxidative coupling of cyclopropanols with boronic acids.  The desired coupling product was never observed, but an a,�-unsaturated ketone was isolated in high yield.  A palladium-catalyzed reaction using similar conditions was published by Park and Cha, but catalyst loadings of 10 mole % were used.  We have found that palladium loadings of 0.5 mole % or less can be used with our conditions, and the oxygen atmosphere can be replaced with air.  This poster will focus on the discovery of the current process and its substrate scope.

Synthesis of a,�-unsaturated ketones using an oxidative Pd-catalyzed cyclopropanol ring opening

247th National Meeting (2014)

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