Search

A general procedure for the synthesis of ethyl Z-3-halo-3-nitroacrylates by the reaction of ethyl 3-nitroacrylate with Cl2 or Br2 followed by dehydrohalogenation was proposed. Ethyl Z-3-chloro-3-nitroacrylate was obtained for the first time. The reaction of halonitroacrylates with anilines followed the pathway of the formation of aza-Michael adducts, the dehydrohalogenation of which led to new β-nitro enamines, namely, ethyl Z-2-arylamino-3-nitroacrylates.

A group of available catalysts based on polyethylenimine quaternized with p-xylylene dichloride followed by subsequent exchange of anions was developed. The influence of the nature of halide ions and electronic and steric factors of the substituents in epoxides on the reaction rate of carbon dioxide addition to epoxides was studied. The catalytic capabilities of the adduct of polyethylenimine with iodine were considered.

The results of studying electrochemical conversions of 7-R-3-X-1,2,4-triazolo[5,1-c][1,2,4]-triazin-4-ones (Triazavirin® and its derivatives) using cyclic voltammetry, chronoamperometry, and ESR spectroscopy are presented. The derivatives of 7-R-3-X-1,2,4-triazolo[5,1-c][1,2,4]-triazin-4-ones were found to be capable of electrochemical reducing in the potential range from −0.16 to −0.68 V (vs Ag/AgCl) in a Britton—Robinson buffer at pH 2–12. At the potentials of the first electroreduction step at pH 2–6, the main process of transformations is the four-electron scheme of reduction of the nitro group of Triazavirin®. The adduct of the radical substances with the spin probe N-(1-hydroxy-2,2,6,6-tetramethylpiperidin-4-yl)-2-methylpropanamide was registered after the preliminary generation of the Triazavirin® radical anion at −0.5 V vs Ag/AgCl in an acidic medium. A linear dependence of the current of the first electroreduction step of the Triazavirin® on the concentration was obtained at pH 2 (linearity range from 10−4 to 1.6 · 10−2 mol L−1, I = −1.93 · C, R2 = 0.9977).

1,3-Cyclopentadienes, fulvenes and their derivatives regio- and stereoselectively react with the in situ generated dichloroketene to form the corresponding bicycles of the [3.2.0]heptane topology. The latter are transformed into block synthons with a higher synthetic potential, including chiral ones. A number of examples are used to demonstrate the possibility of their use in the targeted synthesis of bioactive cyclopentanoids.

New metal-organic frameworks [Mn(DMF)2(odabco)2](ClO4)2 · H2O (1), [Mn(H2O)2− (HCOO)2] · odabco (2), and [Mn(Hodabco)2(odabco)3](NO3)4 (3) were synthesized by the reaction of manganese Perchlorate with 1,4-diazabicyclo[2.2.2]octane N,N′-dioxide (odabco) in N, N-dimethylformamide (DMF) under varying reaction conditions. The reaction in N-methylpyrrolidone afforded the metal-organic framework [Mn(odabco)3](NO3)2 (4). The structures of compounds [Mn(DMF)2(odabco)2](ClO4)2 · DMF · H2O (1 · DMF · H2O), [Mn(DMF)2(odabco)2](ClO4)2 · THF (1 · THF), 2, 3, and 4 were determined by single-crystal X-ray diffraction analysis. In compounds 1 · DMF · H2O, 1 · THF, 3, and 4, odabco acts as a bridging ligand; in 2, as a guest template. Compound 1 · DMF · H2O has a layered structure and contains a system of intersecting channels occupied by perchlorate anions and disordered solvent molecules. The framework of 1 proved to be stable during the post-synthetic exchange of DMF by THF. The coordination framework of the adduct 1 · THF containing localized THF molecules has a similar structure. The layered (2) and chain-like (3) compounds are stabilized by extensive hydrogen-bonding systems, giving rise to pseudo-three-dimensional close-packed structures. The replacement of DMF by N-methylpyrrolidone under conditions similar to the synthesis of 3 affects the coordination ability of odabco and affords compound 4 having a three-dimensional framework with pcu topology.

Polymerization of methyl methacrylate in the presence of 2,5-di-tert-butyl-p-benzoquinone is a combination of two processes: inhibited and controlled radical polymerization. The adduct of chain propagation radicals and p-quinone formed due to the inhibited polymerization is a macroinitiator of controlled radical polymerization. The fraction of the pseudo-living process is determined by the concentration of p-quinone in the starting polymerized composition. Post-polymerization proceeds via the reversible inhibition mechanism.

Hydroxyl-containing compounds (water, methanol, and phenol) act as efficient catalysts of the chain reactions of thiophenol with quinone imines at their propagation steps as it was found previously for thiols. The results of quantum chemical analysis of isomerization of a radical adduct into phenoxyl radical or corresponding aromatic aminyl radical are considered. The adduct was formed at the rate limiting step of the chain propagation by thiyl radical addition to quinone imine. Enthalpies and activation energies for mono- and bimolecular isomerization of the adduct with participation of hydroxyl-containing compounds were computed and matched. For comparison, analogous reactions with participation of thiols (hydrogen sulfide, metahnthiol and thiophenol) were also studied. In both the cases, the catalytic effect is caused by transforming the four-membered cyclic transition state of the monomolecular isomerization reaction into the energetically favorable six-membered transition state by the O—H or S—H groups of the indicated compounds. This considerably reduces the activation energy.

Ferrocenium hexafluorophosphate reacts with aminophosphines P(NEt2)3, PhP(NEt2)2, Ph2P(NEt2), CyP(NEt2)2, and Pri2P(NEt2) to form ferrocenylphosphonium salts [(C5H5)-Fe(C5H4PRR′R″)](PF6), ferrocene, and [HPRR′R″](PF6). The theoretical analysis of the reactions (M06-L/6-311++G(d,p)) showed that these reactions involve a sequence of the following steps: the addition of phosphine to the cyclopentadienyl ring, the oxidation of the initial adduct by the starting ferrocenium to give a dicationic η4-phosphocyclopentadiene complex with an agostic $$C_{sp^{3}}-H\rightarrow{Fe}$$ bond, and the deprotonation of this bond to form ferrocenylphosphonium salts. The resulting ferrocenylphosphonium salts are resistant to alcoholysis and do not react with carbon disulfide.

Mono- and dinuclear adducts of cobalt diketonates with tetradentate 4,7-phenanthroline- 5,6-dione were modeled within the framework of DFT UB3LYP*/6-311++G(d,p) approximation. A competitive coordination of the metal ion to different donor centers of the redox-active ligand was studied. Variation of substituents in the diketone moieties allowed one to reveal compounds than can undergo thermally initiated one- and two-step valence tautomeric rearrangements. The calculated energy and magnetic characteristics of the dinuclear complexes give reasons to consider them as potential basis of molecular electronics and spintronics devices.

A computer simulation of 2 : 1 adducts of cobalt azomethine complexes with pyrene-4,5,9,10-tetraimine was carried out within the framework of the density functional theory (DFT B3LYP*/6-311++G(d,p)). It was shown that the variation of the substituents at the nitrogen atoms of cobalt bischelates, as well as the annulation of the five-membered ring to the azomethine fragment, considerably affects the relative energies of the isomers with different spin states. Compounds, which can manifest one- and two-step redox-isomeric rearrangements, accompanied by the migration of paramagnetic centers, were revealed.

Carane-derived β-amino alcohols with amino and hydroxy groups at positions 3 and 4 differing in their mutual arrangement and configuration were synthesized. Their application as organocatalysts in the asymmetric aldol reaction of isatin with acetone allowed one to obtain adducts with up to 84% enantiomeric excess.

N-Alkyl-2-arylmethylideneindoxyls upon exposure to UV or visible light undergo dimerization not to cyclobutane adducts as it has been reported earlier, but to spiropyrano[3,2-b]-pseudoindoxyls with a spiropseudoindoxyl fragment characteristic of many natural alkaloids. The structure of spiropyranopseudoindoxyls was established by NMR spectroscopy and X-ray crystallography.

The tautomerism of the reaction products of propanal with 4-aminobenzoic acid in ethanol was studied by J-modulated spin-echo (JMOD) 13C NMR spectroscopy and gradient-enhanced heteronuclear (ge-2D) 1H–13C HSQC spectroscopy. The existence of imine and enamine tautomeric forms of the reduced compounds in solution was established. The tautomeric equilibrium of the condensation product of propanal with 4-aminobenzoic acid in ethanol was found to be shifted toward the imine form. Quantum chemical calculations by the density functional theory (DFT) method demonstrated that the 4-(N-propylidene)aminobenzoic acid molecule forms a stronger hydrogen bond with an ethanol solvent molecule compared to the enamine molecule, resulting in a higher stability of the ethanol adduct of azomethine compared to the adduct of enamine.

1,4-Dichloro-3a,6a-diaza-1,4-diphosphapentalene reacts with sodium acetylacetonate to form an adduct of diacylcarbene with trivalent dicoordinated phosphorus. In solution this adduct dimerizes according to the head-to-head type. The phosphorus atoms undergo transformation from the hypervalent state (in the adduct), in which the lone electron pair on the phosphorus atom is not involved in the formation of additional bonds with this phosphorus(III) atom, to the pentavalent pentacoordinated and trivalent tricoordinated state (in the dimer).

Aza-Michael reaction of (E)-4-(diphenylphosphoryl)but-3-en-2-one (1) with a number of mono-and bicyclic nitrogen heterocycles proceeds regioselectively in the absence of catalysts with the formation of corresponding β-azahetaryl β-diphenylphosphoryl ketones; in the case of imidazole, the presence of chiral organic catalysts allows one to increase the yields of the adducts and to obtain them in enantiomerically enriched form.

A density functional B3LYP*/6-311++G(d,p) quantum chemical study of the interaction of FeII complexes with o-diiminobenzoquinones showed that adduct formation is accompanied by oxidation of the metal ion and conversion of the redox-active ligand to the semiquinonate form. Variation of substituents at nitrogen atoms of the bis-chelate and diimine made it possible to reveal the spin-crossover complexes. The nature and strength of the exchange interactions between the unpaired electrons of paramagnetic centers of the adducts studied depend on the spin state of their isomers and on the type of the iron complex.

The reaction of 2-aryl-1,1-dibromocyclopropanes with adduct NOCl·(SO3) n leading to 3-aryl-5-bromoisoxazoles as a result of nitrosation—heterocyclization of the cyclopropane ring was studied. The reaction is accompanied with electrophilic aromatic bromination. The mechanism of the transformation was discussed, the optimal reaction conditions to enhance the reaction selectivity were developed.

The crystal and molecular structure of the reaction product of imidazolidine-2-thione and molecular iodine of the composition (C3H6N2S)2•3I2 was established by X-ray diffraction. The crystal structure is composed of strongly connected five-component associates consisting of three I2 molecules and two heterocyclic molecules. Quantum chemical calculations followed by the topological analysis of the electron density function provided an estimate of the strongest intermolecular interactions in the crystal structure of the molecular adduct.

Nitrosation of 2-(1-adamantylmethyl)-1,1-dichlorocyclopropane with either adduct NOCl•(SO3) n or nitrosonium tetrafluoroborate gives 3- and 4-(1-adamantylmethyl)-5-chloroisoxazoles in good yields. The presence of a linker between cyclopropane ring and adamantane moiety is essential for enabling nitrosation—heterocyclization of adamantyl 1,1-dichlorocyclopropanes.

The acid-catalyzed condensation of 1,3-butadienes with p-quinones and oxidation of the obtained adducts can be carried out as one-pot process in the presence of aqueous solutions of Mo–V–P-heteropolyacids (HPA) of the general composition HaPzMoyVxOb. These solutions act as bifunctional catalysts, since they simultaneously behave as strong Bronsted acids and fairly strong reversible oxidants. The condensation of 1,4-naphthoquinone (NQ) with 1,3-butadiene in solutions of high-vanadium HPA of the empirical compositions H15P4Mo18V7O89 and H17P3Mo16V10O89 in the presence of water-miscible organic solvents (acetone, 1,4-dioxane) affords 9,10-anthraquinone in a yield of ~70% and purity up to 97% at a complete conversion of NQ. Under similar conditions, the reactions of NQ and substituted 1,3-butadienes afford substituted anthraquinones in the yields up to 90% and purity up to 99%. The catalysts are regenerated with oxygen in an individual step and can be reused.

The electronic structures of lanthanide tris(β-diketonate) complexes and their adducts, being of interest as luminophores, were studied by UV photoelectron spectroscopy of vapors and X-ray photoelectron spectroscopy. The spectral regularities identified by the density functional theory revealed the influence of the substitution of the Me groups in the ligands by But, CF3, and neutral ligand in the adducts on the electronic structure of the complexing agent from Pr to Lu.

3a,6a-Diaza-1,4-diphosphapentalene (1), as a neutral ligand, displays a new type of complexation, such that the lone pair at the phosphorus atom is not involved in the coordination; instead, the 10π-electron system provides two electrons for the coordination bond formation between the phosphorus atom and the metal. The p(π)-type complex–a molecular adduct of 1 with germanium dichloride — was synthesized and completely characterized. This complex is a coordination polymer with short intermolecular Ge—Ge, Ge—P, P—P, P—Cl, and Ge—C contacts.

Thermolytic decomposition of 3,3’-(ethan-1,2-diyl)bis(1-methyl-1H-imidazolium) bis-(hexafluorophosphate) (1) under reduced pressure results in a 1: 1 mixture of pentafluo-ro(1-ethenyl-3-methyl-2,3-dihydro-1H-imidazole-2-ylidene-κC 2)phosphorous (2) and penta- fluoro(3-methyl-1H-imidazole-κN 3)phosphorous (3) in an almost quantitate yield. Products 2 and 3 were isolated as individual compounds by fractional recrystallization from hot methanol. Direct observation of a 1: 1 co-crystallite of 2-pentafluorophosphanyl-1-ethenyl-3-methyl-1H-imidazolium hexafluorophosphate and adduct 2 (compound 5) as a minor coproduct of this reaction reveals a complicated path of the thermolysis. Crystal and molecular structures of compounds 2, 3, and 5 were established by X-ray diffraction analysis. Compound 2 presents the first example of an N-alkenyl substituted Arduengo carbene adduct with a main Group element Lewis acid. Compound 3 presents the second known organic base N-adduct with PF5.

A reaction of 3-(2-ethoxyphenyl)-substituted chalcone with aminoazoles was studied. The nature of aza groups in aminoazoles was found to affect the regioselectivity of β-amination in the course of the formation of isomeric pyrazolo[3,4-b]pyridine, azolo[1,5-a]- and [4,3-a]-pyrimidine systems and the depth of the reaction were determined. A regulatory role of catalysts and solvents in the direction of the cascade reactions was established. Mechanisms of the reactions were suggested. A significance of the alkoxy substituent in chalcone for stereoselective synthesis of Michael adducts, including 3-(2-ethoxyphenyl)-3-(7-(2-ethoxyphenyl)-5-phenyl-6,7-dihydroazolopyrimidin-6-yl)-1-phenylpropan-1-ones, was demonstrated. The structures of products synthesized were established by 1H and 13C NMR spectroscopy and X-ray diffraction analysis.

An approach to the synthesis of 1,2,4-triazine thienyl and furyl derivatives through the reaction of aromatic nucleophilic substitution of hydrogen was suggested. Oxidation and cine-elimination pathways of aromatization of the intermediate σH-adducts were considered.

The adducts of cobalt aminovinyl ketonates with o-benzoquinones, o-benzoquinone imines, and o-benzoquinone diimines were studied by the density functional theory method (B3LYP*/6-311++G(d,p)). For all of the compounds, the ground states are low-spin structures containing a trivalent cobalt atom and a redox-active ligand in the semiquinonate form. The bulky substituents at the bis-chelate and ligand nitrogen atoms favor a decrease in the energy difference between the low-spin and high-spin isomers of the adducts containing LSCoIII and HSCoII atoms, respectively. These compounds can exhibit valence tautomerism in the crystalline state, but the relatively low stabilization energies of the high-spin isomers in solutions may induce a competing process: dissociation into the original bis-chelate and redox-active ligand.

N-Terpene-containing amino acid derivatives were synthesized by the reaction of dimeric nitroso chlorides, which were prepared from 3-carene, α-pinene, and limonene, with simplest amino acids or their esters. In the case of 3-carene and α-pinene, the corresponding adducts are formed stereospecifically.

Phosphorylation of 1,6-dihydroxynaphthalene with various triamidophosphites gives 2: 2 cyclic adducts with the 1,6′,1′,6-bonding of the naphthalenediyl moieties through the amidophosphite bridges.

Aryldiazomethanes generated by vacuum thermolysis of arenecarbaldehyde tosylhydrazone sodium salts react stereospecifically with 16-dehydropregnenolone acetate. Subsequent decomposition of the pyrazoline adducts yielded hitherto unknown substituted [16α,17α]-cyclopropaprogesterones bearing the aryl substituents at the position 3′. Interaction of such cyclopropaprogesterones with progesterone receptor from rat uterine cytosol was studied.

The reaction of 2-(2-benzylidenamino)phenoxy-4-tert-butylbenzo-1,3,2-dioxaphosphol with ethyl mesoxalate and ethyl trifluoropyruvate resulted in the formation of tricyclic phosphoranes with the P-C and P-N bonds. The adduct emerged from the initial reaction of the PIII derivative with the activated ketone (1: 1), further underwent the transformation via the intramolecular reaction involving the benzylideniminoaryl substituent, which resulted in the formation of the cage-like phosphoranes.

TsOH-Catalyzed reactions of 6,7-disubstituted 2-hydroxynaphthazarins and acyclic or cyclic α,β-enones afforded the corresponding Michael-type adducts, viz., 3-substituted naphthazarins in 17–78% yields. 1H and 13C NMR and IR spectroscopy showed that the adducts with cyclohexenone and methyl vinyl ketone exist in CDCl3 solutions as mixtures of open-chain and cyclic tautomers, whereas the adducts with cyclopentenones exist only as the open-chain forms.

A reaction of excess of cyclopropane-1,1-dicarboxylates substituted at position 2 with 2-pyrazolines in the presence of 3 equiv. of GaCl3 at 5 °C selectively resulted in the cyclopropanes double addition products, viz., N-substituted 1,2-diazabicyclo[3.3.0]octanes. In this case, the first molecule of the starting cyclopropane formed the bicyclic system, whereas the second added at the N-H bond of the adduct formed. When catalytic amount of Sc(OTf)3 was used in this reaction instead of GaCl3 at 40 °C, besides the corresponding 1,2-diazabicyclo[3.3.0]-octanes, another type of cyclopropane double addition products, viz., N-alkyl-2-pyrazolines, was formed, in which the alkyl chain was assembled from two molecules of the starting cyclopropane. A plausible mechanism for the transformations observed was suggested.

The interaction of tricoordinated cations of the 14th group elements generated by the nuclear chemical method with representatives of π-(aryls, olefins) and n-electron-donating (alcohols, ethers) compounds was studied. A comparative analysis of these interactions was carried out on the basis of the results obtained and revealed the differences in the reaction mechanisms of the carbenium ion compounds and mezoid cations. No drastic differences in the behavior of silylium and germylium cations was observed. The possibility of isomerization of the mezoid cations to donor-acceptor complexes of the [HM+·H2] type was experimentally shown for the first time for dimethylgermylium cations taken as an example. The quantum chemical calculations of the studied cations and adducts of their interactions in terms of the functional density theory prove the reaction mechanisms proposed.

Previously unknown adducts of substituted tryptamines with sesquiterpene lactones, viz., isoalantolactone and its epoxy derivative, were synthesized by the Michael reaction. The compounds obtained were tested for various types of biological activity.

International audience; Efficiency of poly(N vinylimidazole) as the basic recyclable catalyst for the Michael addi tion of CH acids to acrylonitrile, methyl acrylate, methyl vinyl ketone and methyl vinyl sulfone in water at ambient temperature was studied. In these reactions, formation of both 1 : 1 and 1 : 2 adducts is possible.

The sequence of isomeric transformations of intermediate adducts formed upon nuceleophilic addition of β-phenyl-α-alanine to 4-hydroxy-4-methylpent-2-ynenitrile affording a neutral or two alternative zwitterionic forms (with protonated imino or amino groups) of the product was studied quantum chemically by the B3LYP/6-31G(d,p) method and by UV spectroscopy. In the isolated state, the equilibrium is completely shifted toward the neutral form. Taking into account the polyhydrate environment increases the portion of the zwitterionic form bearing a protonated imino group of the dihydrofuran cycle. Protonation of the amino group of amino acid is thermodynamically unfavorable.

A reaction of a lithiated derivative of 4,4,5,5-tetramethyl-3-oxido-4,5-dihydro-1H-imidazole 1-oxyl with 3,6-di-tert-butyl-o-benzoquinone at −80 °C predominantly gave spin-labeled dihydrooxepine via nucleophilic 1,2-addition of the paramagnetic carbanion to the CO group of the benzoquinone followed by insertion of the O atom into the ring. At lower temperatures, this reaction was accompanied by 1,4-addition of the organolithium compound to the benzoquinone followed by oxidation of the resulting adduct into spin-labeled o-benzoquinone. This “one pot” process is a novel approach to organic derivatives that can further be converted into di- and polyradicals combining nitronyl nitroxide and semiquinolate fragments.

Monodisperse 280–480 nm silica particles doped with europium complexes with thenoyltrifluoroacetylacetone and adducts with some phosphine oxides as luminophores were prepared for the first time by the optimized Stober procedure using surfactants. The size and the polydispersity of the obtained particles depend on the luminophore incorporated in the polymer template. The photophysical properties of aqueous dispersions of the europium(iii)-doped silica particles were studied by the luminescence method.

Cycloaddition of η6-(styrene)chromium tricarbonyl to hexa-2,4-diene or cyclopentadiene afford the Diels-Alder adducts with retention of the Cr(CO)3 group, whereas cyclohexa-1,3-diene undergoes aromatization to give η6-(benzene)chromium tricarbonyl. The counter synthesis of these (arene)chromium tricarbonyl derivatives from uncoordinated adducts of the Diels-Alder reaction and chromium hexacarbonyl was carried out.

O- and C-Adducts of 5-(het)aryl-2,3-dicyano-1-ethylpyrazinium salts are latent sources of biradicals capable of forming tetraazaphenanthrene derivatives via dimerization. The mechanisms of the reactions were examined using ESR spectroscopy. The stereochemistry of the resulting heterocyclic systems was studied by NMR spectroscopy. The crystallographic data on their three-dimensional structures were obtained.

The reaction of 5-(het)aryl-2,3-dicyano-1-ethylpyrazinium salts with phenol derivatives affords relatively stable dihydropyrazines, whereas the reactions of 6-(het)aryl-1,2,5-oxadiazolo[3,4-b]pyrazin-4-ium protic salts, depending on the phenol structure, result in products of nucleophilic substitution of hydrogen or open-chain transformation products: benzo[b]furan-substituted derivatives. The crystallographic data on the spatial structure of all types of the synthesized products were obtained.

The addition of •CCl3 and •But radicals to (η2-C70)Os(CO)(PPh3)2(CNBut) (1) and (η2-C70)[Os(CO)(PPh3)2(CNBut)]2 (3) was studied by ESR spectroscopy. The metal fragment in complex 1 does not influence the regioselectivity of the addition of the radicals to it. The stability of the spin adducts formed upon addition of free radicals to complexes 1 and 3 is mainly governed by delocalization of the unpaired electron over three hexagonal rings.

Spin adducts of methanol and ethanol electrocatalytic oxidation were detected by the spin trap method using a tiny ?2/O2 fuel cell (FC) designed for ESR in situ with a Nafion/Pt membrane electrode assembly. Spin adducts of intermediates of the direct electrooxidation of ethanol, which have not been observed earlier, were obtained by the variation of oxidation conditions, in particular, the FC potential. The work of the FC was controlled by monitoring the diagnostic curves potential3-current density, power density3-current density, and efficiency—power density.

Fluorocyclohexa adducts C60(C4F8)n were synthesized by high-temperature reaction of fullerene C60 with 1,2-C2F4I2 or 1,4-C4F8I2 in sealed tubes. Their separation by HPLC allowed us to determine molecular structure (X-ray diffraction) of four new compounds C6(C4F8)n (n = 2, 3, 4, and 6). Structures of isomers C60(C4F8)n were discussed in terms of a concept of consecutive addition of C4F8 groups to the fullerene cage.

Direct aromatic C—H bond activation in the (Sa)-BINOL-derived phosphite (Sa)-HL afforded the dimeric cyclopalladated complex (Sa,Sa)-{Pd(η2-L)(μ-Cl)}2 (2) which is the first optically active PC-palladacycle bearing a phosphorus atom in an axially chiral environment. ortho-Palladated structure of dimer 2 was confirmed by spectral (1H and 31P NMR) examination of its mononuclear derivatives and by X-ray diffraction analysis of the phosphine adduct (η2-L)PdCl(PPh3) (4). The enantiomeric purity of the starting ligand remained unchanged in the PC-palladacycle under the thermal conditions used for the cyclopalladation (∼110 °C); this fact was confirmed by the 31P NMR spectroscopy after chiral derivatization in situ of dimer (Sa,Sa)-2 with the (RC)-valinate chiral auxiliary (Val). trans(N,C)-Configuration of the valinate complex (η2-L)Pd(Val) (5) was established by 1H NMR and supported by DFT calculations. The chirality transfer in the new PC-palladacycle was discussed on the basis of X-ray diffraction data for the phosphine adduct rac-4 and DFT calculations performed for both phosphine and valinate mononuclear derivatives.

The Michael-type addition of dimedone and dihydroresorcinol to β,β-dinitrostyrenes occurs easily without a catalyst. The adducts cyclize into 3-aryl-2-nitro-2,3,4,5,6-hexahydrobenzofuran-4-ones under the action of triethylamine.

Depending of the reaction conditions, reaction of levoglucosenone with diazocyclopropane generated in situ from N-cyclopropyl- N-nitrosourea under the action of bases involved either the carbonyl group to give oxaspiropentane (MeONa/MeOH, s-30 °C), or the double C=C bond to give l-pyrazoline (K2CO3, CH2Cl2, 5 °C). The latter readily reacted with diazocyclopropane at the C=O group or added as a C-nucleophile in a regio-and stereoselective Michael reaction to the C=C bond of levoglucosenone. The direction of reaction depended on the reactant ratio. The reaction of the levoglucosenone—diazomethane adduct with an excess of levoglucosenone in the presence of a base yielded similar product bearing two levoglucosenone moieties.

Resorcinol-based ruthenium bis(phosphinite) complexes were synthesized. Complexes RuCl(CO)[2,6-(But 2PO)2C6H3] (9) and RuH(CO)[2,6-(But 2PO)2C6H3] (10) were obtained by cyclometallation of 1,3-(But 2PO)2C6H3 with RuCl2(DMSO)4 in 2-methoxyethanol in the presence of Hunig’s base. The interconversion of complexes 9 and 10 was studied. The addition of carbon monoxide to complexes 9 and 10 yielded 18e adducts, RuCl(CO)2[2,6-(But 2PO)2C6H3] (11) and RuH(CO)2[2,6-(But 2PO)2C6H3] (12), respectively. In the case of complex 9, this reaction is reversible. Reaction of complex 10 with trifluoroacetic acid resulted in complex Ru(CF3COO)(CO)[2,6-(But 2PO)2C6H3] (13), which reacted with carbon monoxide to give complex Ru(CF3COO)(CO)2[2,6-(But 2PO)2C6H3] (14). Based on the IR spectral data, the TFA ligand in complexes 13 and 14 is bound in a bi- and monodentate fashion, respectively. The structure of compound 9 was determined by X-ray diffraction analysis.

The reaction mechanisms of cycloaddition of nitrobenzofuroxan to cyclopentadiene are studied using DFT calculations at the B3LYP/6-31G* level in the gas phase and with account of the solvation effects. The reaction follows a three-step mechanism and includes the formation of a prereaction donor-acceptor complex, endo [4+2] cycloaddition with inverse electron demands (IED), and [3,3]-sigmatropic rearrangement to the final endo [2+4] adduct. No formation of stable bipolar σ-complexes on the minimum-energy reaction pathways occurs.