Recent developments in enantioselective zinc-catalyzed transformations

Factors controlling the structure of alkylzinc amidinates: on the role of N-substituents

Despite various applications of alkylzinc complexes supported by N,N-bidentate ligands in chemistry and materials science, the corresponding organozinc amidinates still represent an insufficiently explored area. To gain a more in-depth understanding of factors controlling the structure and stability of alkylzinc amidinates, we selected benzamidinate and N,N'-diphenylformamidinate ligands as model N,N'-unsubstituted and N,N'-diaryl substituted ligands, respectively, to systematically modify the secondary coordination sphere of the Zn center. A series of new alkylzinc amidinates has been synthesized and their molecular structures identified in both the solid state (single-crystal X-ray crystallography) and solution (NMR and FTIR spectroscopy). The results indicate that [RZnL]_x-type amidinate moieties are essentially unstable and tend to undergo Schlenk equilibria-mediated ligand scrambling leading to more thermodynamically stable non-stoichiometric [R₂Zn₃L₄]- and [R₃Zn₄L₅]-type complexes. This process is significantly influenced by the secondary coordination sphere noncovalent interactions as well as the steric hindrance provided by both zinc-bounded alkyl groups and the N-substituents.

Recent developments in enantioselective nickel(ii)-catalyzed conjugate additions

This review updates the field of enantioselective nickel-catalyzed conjugate additions since 2016.

An efficient catalytic method for hydrophosphination of heterocumulenes with diethylzinc as precatalyst without a solvent

Commercially available compound ZnEt₂ acts as an efficient precatalyst for the solvent-free hydrophosphinations of heterocumulenes using Ph₂PH as reagent. As far as we knew, this has been not reported in group 12 metal catalyzing reactions. A suggested mechanism of this reaction is explored, and the intermediate [{Ph₂PC(NⁱPr)₂}ZnEt]₂ is obtained and characterized by a single-crystal X-ray structural analysis.