L. V. Sherstyannikova

Structure of bis(trifluoromethanesulfonyl)imide in inert and protophilic media

According to the data of IR spectroscopy, dielectrometry, and HF/6-31G**, B3LYP/6-311G** quantum chemical calculations bis(trifluoromethanesulfonyl)imide (CF3SO2)2NH in nonpolar medium (CCl4) exists as an H-complex formed by its molecules in two tautomeric (NH and OH) forms. In a polar medium (CH2C12) linear chain polyassociates with a bifurcate hydrogen bond are formed similar to those existing in the crystal. In the presence of protophilic solvents ion pairs consisting of the protonated molecule of the base and dimeric anion of bis(trifluoromethanesulfonyl)imide are formed.

Structure and proton donating ability of 2- and 2,5-bis(1-trifluoromethanesulfonylamido-2,2,2-trichloroethyl)pyrroles

Abstract2-(1-Trifluoromethanesulfonylamido-2,2,2-trichloroethyl)pyrrole and 2,5-bis(1-trifluoromethanesulfonylamido-2,2,2-trichloroethyl)pyrrole according to quantum chemical calculations (B3LYP/6-311G**) exist in the isomeric forms whose structure determines the formation of intramolecular hydrogen bonds NH⋯Cl, NH⋯O=S and CH⋯O=S of different strength. Potentiometric and spectroscopic acidity of these compounds is determined. From the data of IR spectroscopy their proton donating ability upon interaction with Lewis bases is shown depending on the presence of intramolecular hydrogen bonds, mutual effects of intermolecular hydrogen bonds formed by the sulfonamide and pyrrole NH groups with the base, and electronic effects of the substituents.

Reaction of α-ethoxyarolein with diethyl malonate

The reaction of α-ethoxyacrolein with diethyl malonate in the presence of EtONa, lithium diisopropylamide, or the Na2CO3−benzene−Et3(PhCH2)NCl catalytic system proceeds as the Michael addition. In the presence of an equimolar amount of triethylamine, selective 1,2-addition followed by dehydration of the 1,2-adduct occurs. Owing to the strong +M effect of the EtO group, α-ethoxyacrolein is a substantially less active Michael acceptor than acrolein.

Synthesis of 2-ethoxyprop-2-enal dimethylhydrazone and its Diels-Alder reactions

Conditions were found for the preparation of 2-ethoxyprop-2-enal dimethylhydrazone by reaction of 2-ethoxypropenal with N,N-dimethylhydrazine. 2-Ethoxyprop-2-enal dimethylhydrazone reacted with methyl vinyl ketone and methyl acrylate according to the [4 + 2]-cycloaddition pattern with regioselective formation of substituted tetrahydropyridines. The major product in the reaction of 2-ethoxyprop-2-enal dimethylhydrazone with 1,4-benzoquinone was 5-hydroxy-1-benzofuran-2-carbaldehyde dimethylhydrazone formed as a result of [3 + 2]-cycloaddition; a small amount of the corresponding [4 + 2]-cycloaddition product was also obtained. Some spontaneous transformations of the primary cycloaddition products were revealed.

Synthesis and steric structure of N″-(arylmethylidene)-N″′-(1-methyl-3-phenylprop-2-yn-1-ylidene)thiocarbonohydrazides

Thiocarbonohydrazones derived from aromatic aldehydes reacted with 4-phenylbut-3-yn-2-one in aqueous acetic acid (20°C, 2 h) to produce previously unknown N″-[(E-s-cis)-arylmethylidene]-N″′-[(Z-s-trans)-1-methyl-3-phenylprop-2-yn-1-ylidene]thiocarbonohydrazides with high chemo-, regio-, and stereoselectivity. The steric structure of N″-[(E-s-cis)-benzylidene]-N″′-[(Z-s-trans)-1-methyl-3-phenylprop-2-yn-1-ylidene]thiocarbonohydrazide in crystal and in solution was studied by X-ray analysis and IR and NMR spectroscopy.

Synthesis of N-(trifluorosilylmethyl)glutarimide. Alternate intramolecular coordination of the silicon atom to two oxygen atoms

A new representative of draconoids, N-(trifluorosilylmethyl)glutarimide, was synthesized by reaction of N-(trimethyoxysilylmethyl)glutarimide with boron trifluoride-ether complex. According to the IR and 1H, 13C, 15N, 19F, and 29Si NMR data, this compound molecule is characterized by intramolecular coordination between the silicon and carbonyl oxygen atoms (alternate coordination of the silicon atom to each oxygen atom).

Synthesis of 3,3-Dialkoxy-2-trialkylsiloxypropenes

Silylation of 1,1-dialkoxy-2-propanones with trimethyl- and tert-butyldimethylsilyl chlorides and trifluoromethanesulfonates in the presence of triethylamine and/or 1,8-diazabicyclo[5.4.0]undec-7-ene in various solvents leads to 2-trialkylsiloxypropenal acetals in up to 60% yield.

Cyanosilylation of α-butylthioacrolein

Cyanosilylation of α-butylthioacrolein with trimethylsilyl cyanide occurs as 1,2-addition. Concurrent rapid dimerization of α-butylthioacrolein occurred both in the presence and in the absence of H2PtCl6·6H2O as a catalyst to give 2,5-dibutylthio-2,3-dihydro-4H-pyran-2-carbaldehyde, whose cyanosilylation afforded the corresponding cyanohydrin. The latter is prone to retrodiene degradation upon heating.