Nickel-Catalyzed Asymmetric Allylic Alkylation of β-Dicarbonyl Compounds via C–C Bond Activation of 2-Allylated Cyclic 1,3-Diketones

Abstract

The asymmetric allylic alkylation (AAA) reaction using less reactive, stable allylic sources is challenging. We achieved a nickel(0)-catalyzed AAA reaction of β-dicarbonyl compounds under ambient conditions through unstrained C–C bond activation of 2-allylated 2-methylcyclohexane-1,3-dione derivatives to afford the corresponding quaternary chiral compounds in high yield with high enantioselectivity. The reaction proceeded almost irreversibly due to the low solubility of the side-product, 2-methylcyclohexane-1,3-dione. Control experiments and DFT calculations allowed for the elucidating the mechanism of the AAA reaction with the Ni(0)-(S)-tol-MeO-BIPHEP catalyst system; the turnover limiting step is C–C bond formation, and the reverse reaction requires 7.6 kcal mol–1 higher activation energy than the forward reaction.