Fig. 2. The challenges involved in developing site-selective reductive hydroalkylation reactions.

As shown in the Ni catalytic cycle, the key to efficient transformation of 4 to 5 requires faster conversion of intermediate ii to iv in order to suppress adventitious formation of the undesired dialkylation adduct 6. Under the reductive conditions, both the hydrogen and alkyl unit are derived from the haloalkane reagent. R, G, functional group; X, halide; L, ligand; cat., catalyst.