Yu. H. Budnikova

Ligand-directed electrochemical functionalization of C(sp2)—H bonds in the presence of the palladium and nickel compounds

The recent achievements of electrochemical functionalization of C—H bonds in aromatic substrates containing the pyridine moiety and acting as a ligand directing substitution to the ortho-position in the presence of the palladium and nickel compounds are analyzed and generalized in the review. Acetoxylation, perfluoroacetoxylation, perfluoroalkylation, and phosphorylation are considered for 2-phenylpyridine (PhPy) as an example. The PdII metallocycles with the Pd-bound acetate, perfluoroacetate, and perfluoroheptanoate substituents were isolated and characterized as possible intermediates: binuclear [(PhPy)Pd(µ-OAc)]2 and [(PhPy)Pd(µ-TFA)]2 and mononuclear [(PhPy)Pd(TFA)](MeCN), [(PhPy)Pd(TFA)](PhPy), [(PhPy)Pd(PFH)](PhPy), and [(PhPy)Pd(EtO)2P(O)]2. Their electrochemical properties were studied. The fluorinated derivatives are in solvent-dependent equilibrium between the mononuclear and binuclear forms. Cyclic voltammetry was used to establish the redox properties of the palladium cycles and routes of their oxidation to the final products. A new approach to CH-substitution products based on the electrochemical generation of Pd or Ni in high oxidation states in the presence of substrate-ligand was proposed.

Electrochemical synthesis of organophosphorus compounds with PO, PN and PC bonds from white phosphorus

The conditions of electrochemical oxidation of white phosphorus are studied, and direct electrochemical methods for the synthesis of esters of phosphoric, phosphorous and phosphonic acids, amidoesters and trialkyl and triaryl phosphines from white phosphorus were elaborated. Equipment allowing the processes to be carried out continuously and under fire-safe conditions using synthesis of triethyl phosphate was tested as an example. The proposed processes are suitable for industrial technology.

New method of metal-induced oxidative phosphorylation of benzene

A new approach to phosphorylation of benzene with diethyl phosphite is suggested, which is based on the electrocatalytic oxidation of a mixture of benzene and diethyl phosphite (1 : 1) under mild conditions (room temperature, normal pressure) in the presence of bimetallic catalytic systems MnII/CoIIL (MnSO4/CoCl2dmphen or MnCl2/CoCl2bipy). This method gives diethyl phenylphosphonate in high yield (up to 90%) and practically 100% conversion of the phosphite.

Electrochemical C-H phosphorylation of 2-phenylpyridine in the presence of palladium salts

A new approach was developed to the introduction of the phosphonate group into arylpyridines using 2-phenylpyridine as an example. The approach is the electrochemical oxidation of a mixture of 2-phenylpyridine, diethyl phosphite, and palladium acetate at room temperature. An intermediate dipalladium cyclic complex was isolated that is formed by the ortho-palladation of 2-phenylpyridine and substitution of acetate ions by phosphonate ions. The preparative oxidation of this complex selectively results in the product of the phosphorylation of the C-H bond in 2-phenylpyridine.

Electrocatalytic fluoroalkylation of olefins. Perfluoroalkylation of 2-vinylpyridine

Perfluoroalkylation of 2-vinylpyridine was conducted under conditions for the formation of low-valent nickel complexes during electroreduction of NiBr2L (L is the bipy, terpy) in DMF solutions. Depending on the electrosynthesis conditions, either dimeric products of addition of perfluoroalkyl substituents at the double bond of the olefin or (in the presence of triethylamine) 1-perfluorohexyl-2-pyridinethylene were formed.

Electrochemical phosphorylation of coumarins catalyzed by transition metal complexes (Ni—Mn, Co—Mn)

A possibility of electrochemical phosphorylation of coumarins (coumarin, 6-methylcoumarin, 7-methylcoumarin) with diethyl phosphite was shown. The approach is based on the oxidation of a mixture of the aromatic compound and diethyl phosphite (1: 1) under mild conditions (room temperature, atmospheric pressure) in the presence of a bimetallic catalytic systems: MnIIbipy/NiIIbipy and MnIIbipy/CoIIbipy (bipy is the 2,2´-bipyridine). This method allows one to obtain diethyl arylphosphonates in high yields (up to 70%) and 100% conversion of the phosphite.

“Green” Ways of Phosphorus Compounds Preparation

Essentially new approach to organophosphorus compounds (OPC) synthesis first of all with P─O, P─C or P─H bonds, resource saving and ecologically safe, from white phosphorus in electrocatalytic conditions, and effective universal technology of electrosynthesis of lines of OPC compounds were created.

Kinetic features of oxidative addition of organic halides to the organonickel σ-complex

Electrochemically generated organonickel σ-complexes were used as model compounds to study the kinetics of oxidative addition of ArNiIbpy to RX, the key stage of cross-coupling of organic halides (RX). The reaction rate constants were calculated, and the sequence of relative reactivity of RX toward the electrochemically generated MesNiIbpy complex was obtained.

Electrochemical synthesis of phosphorus esters from white phosphorus in the presence of copper complexes and ethanol

In the presence of white phosphorus the redox potentials of the copper ions change and the potential of the reduction wave of CuI/Cu0 shifts noticeably toward more positive values. The CuI—P4 complex is characterized by a lower value of the electrochemical gap, that is, higher polarizability and reactivity compared to those of the free CuI cation. Phosphorus esters can be synthesized from P4 and ethanol. The latter is in the composition of the copper(ii) complexes, which act as a catalyst-charge mediator.

Oxygen reduction reaction catalyzed by nickel complexes based on thiophosphorylated calix[4]resorcinols and immobilized in the membrane electrode assembly of fuel cells

The catalytic activity of the nickel complexes of thiophosphorylated calix[4]resorcinols for oxygen reduction in a polymer electrolyte membrane fuel cell (PEMFC) has been studied. The conformation of the macrocyclic ligand determines the morphology and catalytic properties of the resulting organometallic species.