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45567-AC1
Rhodium-Catalyzed Addition of Alkynes to Activated Ketones and Aldehydes

John D. Chisholm, Syracuse University

PRF# 45567-AC1

Rhodium-Catalyzed Addition of Alkynes to Activated Ketones and Aldehydes

      Studies on ligand effects in the rhodium-catalyzed addition of alkynes to aldehydes and activated ketones are ongoing. Modification of the b-diketonate ligand has been shown to have a significant effect on the reaction rate and the yield of the reaction (eq. 1).  Incorporation of electron withdrawing groups on the b-diketonate ligand significantly reduced the efficacy of the transformation, while electron-releasing groups had the opposite effect.  Importantly, bulky t-Bu and Ph groups were well tolerated.  The use of chiral b-diketonate ligands with bulky groups at these positions will next be explored.

  (1)

      The expansion of transition-metal catalyzed nucleophilic addition reactions to the addition of aryl and vinylboronic acids to 1,2-diketones and 1,2-ketoesters was also explored.  Several literature reports describe rhodium metal complexes as excellent catalysts for the addition of aryl and vinylboronic acids to aldehydes, but 1,2-dicarbonyl electrophiles were conspicuously absent from these studies.  Reaction conditions using catalytic Rh(acac)(CO)₂ and PPhCy₂ provide excellent yields of these addition products (eq. 2). 

  (2)

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