Asymmetric Zinc-Catalyzed Hydrosilylation of Ketones and the Effect of Carboxylate on the Enantioselectivity

Catalytic Hydroboration and Reductive Amination of Carbonyl Compounds by HBpin using a Zinc Promoter

In this paper, the chemoselective hydroboration of aldehydes and ketones, catalyzed by Zinc(II) complexes [ k 2 -(PyCH=NR)ZnX 2 ] [R = CPh 3 , X = Cl ( 1 ) and R = Dipp (2,6-diisoropylphenyl) and X = I ( 2 )], in the presence of pinacolborane (HBpin) in ambient temperature and solvent-free conditions, which produced corresponding boronate esters in high yield, is reported. Zinc metal complexes 1 and 2 were derived in 80-90% yield from the reaction of iminopyridine [PyCH=NR] with anhydrous zinc dichloride in dichloromethane at room temperature. The solid-state structures of both zinc complexes were confirmed using X-ray crystallography. Zinc complex 1 was also used as a competent pre-catalyst in the reductive amination of carbonyl compounds with HBpin under mild and solvent-free conditions to afford a high yield (up to 97%) of the corresponding secondary amines. The wider substrate scope of both reactions was explored. Catalytic protocols using zinc as a pre-catalyst demonstrated an atom-economic and green method with diverse substrates bearing excellent functional group tolerance. Computational studies established a plausible mechanism for catalytic hydroboration.

Carbonyl and ester C–O bond hydrosilylation using κ4-diimine nickel catalysts

(^Ph2PPrDI)Ni chemoselectively catalyzes α-allyl ester C–O bond hydrosilylation to prepare silyl esters with turnover frequencies of up to 990 h⁻¹.

Pure phosphotriesters as versatile ligands in transition metal catalysis: efficient hydrosilylation of ketones and diethylzinc addition to aldehydes

The phosphate fate: will proving the versatility of phosphate ligands in catalysis make them finally attractive?

Enantioselective Hydrosilylation of Imines Catalyzed by Chiral Zinc Acetate Complexes

A series of zinc acetate complexes with optically pure diphenylethanediamine (DPEDA)-derived ligands have been employed as enantioselective catalyst for the hydrosilylation of various imines. High control of stereoselectivity (up to 97% ee) and excellent yields (up to 96%) were gained for a broad range of N-phosphinoylimines by using (R,R)-N,N'-dibenzyl-1,2-diphenylethane-1,2-diamine. This is the first successful application of an air-stable and environmentally friendly chiral Zn(OAc)2 complex instead of the previously used harmful diethylzinc in the asymmetric reduction of the C═N double bond.