G. D. Kolomnikova

Synthesis, structure and isomerism of “three-bridge” exo-nido-osmacarborane clusters

The reaction of OsCl2(PPh3)3 with [nido-7-R1-8-R2-C2B9H10]K+ produced a series of new exo-nido-osmacarborane complexes exo-nido-5,6,10-[Cl(Ph3P)2Os]-5,6,10-(μ-H)3-10-H-7-R1-8-R2-7,8-C2B9H6 (1: R1 = R2 = H; 2: R1 = R2 = Me; 3: R1 = R2 = PhCH2; 4: R1 + R2 = 1,2-C6H4(CH2)2; 5: R1 = H, R2 = Me) in which the osmium-containing group is linked to the nido-carborane ligand through three two-electron three-center bonds. Compounds 1—5 are formed as mixtures of symmetric (a) and asymmetric (b) isomers; pure symmetric isomers 2a and 4a were isolated by fractional crystallization, and the mixture of isomers 3a, was quantitatively separated into individual compounds 3a and 3b by column chromatography on silica gel. Detailed analysis of the 31P{1H}, 1H, 11B NMR spectra of 1a,b—5a,b and 2D 1H-1H{11B} and 11B{1H}-11B{1H} NMR spectra of 3a and 3b was performed. The structures of isomers 2a and 4a were confirmed by an X-ray diffraction study. According to the NMR and X-ray diffraction data, the isomerism of exo-nido-complexes 1a,b—5a,b is actually the cis—trans-isomerism of ligand arrangement in the octahedral coordination of the Os atom.

A new insertion reaction of phenyl isocyanate

A new reaction of the insertion of phenyl isocyanate into the C-C bond of P-containing zwitterions based on 2-cyanoacrylates was found. A probable mechanism of this reaction has been discussed.

Alkylation of P-containing zwitter-ions based on 2-cyanoacrylates

The interaction of P-containing zwitter-ions based on ethyl 2-cyanoacrylate with methyl iodide, allyl bromide, α-bromoacetophenone, and 1,3-dichloroacetone has been studied. Alkylation occurs at the central carbon atom of the pentade anion.

2-Cyanoacrylates in the conjugate addition of trifluoroacetic acid and nucleophilic reagents

In the presence of trifluoroacetic acid, ethyl 2-cyanoacrylate readily reacts with nucleophilic reagents, such as 2-chloro-1,3,2-benzodioxaphosphole, (EtO)3P, (EtO)2PCl, Ph2PCl, Ph3P, and thiourea. In these reactions the acid proton enters position 2 of the cyanoacrylate, whereas the nucleophilic component enters position 3, in accordance with the electron density distribution in the acrylate. In the absence of trifluoroacetic acid the above reagents, except 2-chloro-1,3,2-benzodioxaphosphole, cause ethyl 2-cyanoacrylate polymerization. The interaction of ethyl 2-cyanoacrylate with 2-chloro-1,3,2-benzodioxaphosphole and trifluoroacetic acid is the first example of a 2-cyanoacrylate taking part in the acid-initiated electrophilic conjugate addition of a weak nucleophile.

Anticholine esterase activity of phosphonium bis-zwitterions based on 2-cyanoacrylates

Phosphonium bis-zwitterions based on bis-2-cyanoacrylates are weak reversible inhibitors of choline esterases with a diverse anticholine esterase effect. This can find use in additional classification of choline esterases.

The vinyl esters of phosphorus acids. 32. Phosphorus-containing isothiuronium salts

The vinyl esters of phosphorus acids containing an α-chloromethylalkenyl substituent react readily with thiourea to form substituted phosphorylated S-isothiuronium chlorides, capable of being dialkylated to the corresponding internal salts (betaines). An allylic rearrangement was discovered for the first time in the series of substituted S-isopropenylisothiuronium salts. The anticholinesterase and toxicological characteristics of some of the obtained comopunds were measured and compared.

Hydrogenation of ?-cyanoacrylic acid and its esters by organohydridesilanes

The C=C bond in α-cyanoacrylic acid is readily hydrogenated by organohydridesilanes in the absence of catalyst. The hydrogenation of α-cyanoacrylate esters requires the presence of acid.

Reaction of ?-cyanoacrylic acid and cyanoacrylates with dialkyl and diaryl phosphites

Abstractα-Cyanoacrylic acid and α-cyanoacrylates add dialkyl and diaryl phosphites and diethyl thiophosphite at the C=C double bond in the absence of catalyst. This is an anti-Markovnikov reaction, which yields the corresponding phosphonates and thiophosphonates.