Sulfuryl Fluoride Mediated Synthesis of Amides and Amidines from Ketoximes via Beckmann Rearrangement

A metal-free and redox-neutral method for Beckmann rearrangement employing inexpensive and readily available SO₂F₂ gas is described. The reported transformation proceeds at ambient temperature and is compatible with a wide range of sterically and electronically diverse aromatic, heteroaromatic, aliphatic and lignin-like oximes providing amides in good to excellent yields. The reaction proceeds through the formation of an imidoyl fluoride intermediate that can also be used for the synthesis of amidines.     

Partial gas-phase oxidation of hydrocarbon gases with an adjustable methanol-to-carbon monoxide ratio in the oxidation products

Experimental results on the partial oxidation of methane-ethane and C₁–C₄ alkane gas mixtures are reported. The effect of the parameters of the process on the methanol-to-carbon monoxide ratio in the reaction products is examined and the possibility to control this ratio, important for the subsequent carbonylation of the products, is demonstrated.     

EPR Study of Ligand Effects in Spin Triads of Bis(o-Semiquinonato)Copper(II) Complexes

We report the X-band (9 GHz) electron paramagnetic resonance (EPR) study of series of bis(o-semiquinonato)copper(II) complexes with different ligands. It was found previously, that exchange interactions in spin triads of these compounds are very sensitive to the structure of the ligand coordinated to the central copper(II) ion. Ligand moderates the copper–radical and radical–radical exchange interactions and strongly changes the magnetic properties of the compound. Depending on a ligand, ferromagnetic or antiferromagnetic character of exchange dominates in the system. The EPR study of these complexes allowed us to obtain information on zero-field splitting parameters and their distributions in the studied compounds. The EPR results compliment previously obtained spectroscopic data on these compounds and suggest the pronounced plasticity of the clusters manifested in the broad distributions of their rhombicity parameters.     

Spin transition in the molecular heterospin complex of Cu(hfac)2 with 4,4,5,5-tetramethyl-2-(1-methylpyrazol-5-yl)-4,5-dihydroimidazole-1-oxyl 3-oxide

The synthesis, structure, and magnetic properties of the products of the reaction for Cu(hfac)₂ (hfac is hexafluoroacetylacetonate) with spin-labeled nitronyl nitroxides 4,4,5,5-tetramethyl-2-(1-R-1H-pyrazol-5-yl)-3-imidazoline-1-oxyl 3-oxides L^5/R (R = Me, Et, Pr, Bu), viz., binuclear complex [Cu(hfac)₂L^5/Me]₂ and chain polymer complexes [Cu(hfac)₂L^5/R]_n, are described. The polymer heterospin chains are built according to “head-to-head” (R = Me, Et, Pr, Bu) and “head-to-tail” (R = Pr, Bu) motifs. Compound [Cu(hfac)₂L^5/Me]₂ is characterized by the ability to reveal the reversible effect of thermally induced spin transition at a temperature about 75 K (without hysteresis). In the set of heterospin Cu^II compounds with spin-labeled pyrazoles, this is the earlier unknown example of a molecular complex exhibiting a similar magnetic anomaly.     

Stereoselective preparation of mono- and bis-derivatives of pentacyclo[6.3.0.02,6.03,10.05,9] undecane (D 3-trishomocubane)

The rearrangement of easily accessible Cookson’s diketone with chlorosulfonic acid in chloroform followed by the acidic hydrolysis gave 6-chloro-7-hydroxy-dichloropentacyclo[6.3.0.0^2,6.0^3,10.0^5,9]undecane-4-one, whose syn-stereochemistry was assigned through the X-ray crystal structure analysis. This key structure was used for the stereoselective synthesis of the D ₃-trishomocubane derivatives as well as for the preparation of potential drugs bearing hydroxy- and amino-functional groups. A new multigram preparative synthesis of D ₃-trishomocubane was developed.      

Hydrogenation of Intermetallic Compounds ACo3 (A = Ce,Y) with Hydrogen and Ammonia

Russian Journal of Applied Chemistry - The reactions of intermetallic compounds ACo3 (A = Ce, Y) with hydrogen and ammonia at 20–450°C were studied. The composition of the products and...     

Pseudotetrahedral polyhaloadamantanes as chirality probes: synthesis,separation, and absolute configuration

Pseudotetrahedral, conformationally as well as configurationally stable 1-bromo-3-chloro-5-fluoro- (4) and 1-bromo-3-chloro-5-fluoro-7-iodoadamantane (5) (and some related compounds) were prepared by our recently devised phase-transfer catalytic halogenation protocol; the optical antipodes of 4 were separated by HPLC on chiral phase in ee > 99%, and the absolute configurations were assigned by matching observed and computed circular dichroism spectra. Structure 5 is the first chiral aliphatic hydrocarbon containing all stable (nonradioactive) halogens; its structure was proven by NMR spectroscopy and by X-ray crystal data. We emphasize that the combination of experiment and theory is very powerful in assigning absolute configurations even for molecules without typical chromophors, with small values for the optical rotation, and without an atom at the stereogenic center.     

Observation of a stable carbocation in a consecutive criegee rearrangement with trifluoroperacetic acid

Selective oxidative cleavage-cyclization of adamantane through the bridge carbon was developed in trifluoroperacetic acid (TFPAA). The methyl group in the bridge position was found to be the substituent that directs consecutive oxygen insertion into the cage structure during the course of a Criegee rearrangement. The formation of stable 5-methyl-4,6-dioxabishomoadamant-5-yl cation at -25 degrees C was observed. Stable carboxonium ion formation allows control of the selectivity of further transformations. Hydrolysis leads to the stereospecific formation of endo,endo-3-hydroxy-7-acetoxybicyclo[3.3. 1]nonane. Its single-crystal X-ray structure was obtained. An increase in temperature results in deprotonation of the 5-methyl-4, 6-dioxabishomoadamant-5-yl cation to endo-3-trifluoroacetoxybicyclo[3.3.1]non-6-ene, which undergoes further epoxidation with TFPAA and acidic transannular cyclization in trifluoroacetic acid (TFAA). The described reactions can be used as a convenient method for the synthesis of bicyclo[3.3.1]nonane and oxaadamantane derivatives. The proposed mechanism for each transformation, as well as supporting ab initio theoretical calculations of the strain energy and the stabilization energy of the relevant oxacage structures, are discussed.     

Reactions of polyfluorocarbonyl compounds and their trifluoroacetylimines with fused heterocycles

C-Hydroxy- andC-aminoalkylation of iminodibenzyl, iminostilbene, phenoxazine, and phenothiazine with hexafluoroacetone, methyl trifluoropyruvate, and their trifluoroacetylimines were investigated. The substitution occurred at one or severalpara- andortho-positions to the N atom of the heterocycles. In the case of methyl trifluoropyruvate and its derivative the substitution in theortho-position was accompanied by the formation of lactams.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1239–1242, May, 1996.