Approach to alpha,beta-unsaturated ketones through nickel catalyzed aldehyde-free hydroacylation

Abstract

α,β-Unsaturated ketones are widely used as raw materials in the production of fine chemicals, medicines, and natural products. Through chemoselective aldehydic C–H activation, transition metal-catalyzed hydroacylation processes of alkynes employing aldehydes have been recognized as an atom-economical method to access, unsaturated ketones. However, chelating moiety-bearing aldehydes are required in previously described hydroacylation reactions utilizing rhodium, cobalt, or ruthenium catalysts to prevent decarbonylation of acyl-metal-hydride complexes. In the presence of zinc metal as a reducing agent, we present a nickel-catalyzed anti-Markovnikov selective coupling process that yields non-tethered E-enones from terminal alkynes and S-2-pyridyl thioesters. This method, which is not chelation-controlled, has mild reaction conditions and excellent regio- and stereoselectivity.