Transformation of brucine into trifluoromethyl neobrucine using the homoleptic nickel catalyst [Ni(CF3)4]2

The homoleptic trifluoromethyl nickel complex [Ni(CF3)4]2- catalyzes a stereoselective trifluoromethylation of brucine with Umemoto II reagent. The trifluoromethylation process proceeds with concomitant isomerization of its alkenyl double bond leading to a trifluoromethylated neobrucine-like derivative. A minor difunctionalization product was also detected from the reaction mixture, consistent with a radical addition process that is occurring in parallel. Stoichiometric reactions between the nickel(II) catalyst precursor and brucine led to no reaction. However, a stochiometric reaction with a high-valent nickel(IV) complex formed trifluoromethylated neobrucine, implicating its intermediacy. (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

The homoleptic trifluoromethyl nickel complex catalyzes a stereoselective trifluoromethylation of brucine, leading to a trifluoromethylated derivative. The reaction also involves the isomerization of its alkenyl double bond, and a minor difunctionalization product is detected, suggesting a parallel radical addition process. Stoichiometric reactions between the nickel(II) catalyst precursor and brucine show no reactivity, but a reaction with a high-valent nickel(IV) complex results in the formation of trifluoromethylated derivative.