Nickel/Photo-Cocatalyzed Asymmetric Acyl C–H Allylation of Aldehydes and Formamides

Herein,
we developed a highly enantioselective acyl C–H
allylation of aldehydes and formamides, which proceeds under the cooperative
catalysis of a chiral PHOX nickel complex and tetrabutylammonium decatungstate
(TBADT). With readily available Morita–Baylis–Hillman
adducts as the electrophilic allylating agent, the reported reaction
allows for the synthesis of α-stereogenic β,γ-unsaturated
1,4-dicarbonyl compounds in a highly enantioselective manner. The
preliminary mechanistic investigations point to an enantioconvergent
reaction pathway, in which rapid kinetic resolution of the starting
allyl acetates through oxidative addition to Ni(0) is followed by
dynamic kinetic resolution of the resultant allyl Ni(II) complexes
via the interaction with acyl radicals generated by TBADT-mediated
homolytic acyl C–H bond cleavage.