Search

Chiral ferrocene phosphane–carbenes are good ligands for the copper-catalyzed 1,4-addition of Grignard reagents to various Michael acceptors. The products were obtained in high enantiomeric purity (up to e.r. = 95:5) and excellent regioselectivity (r.r. = 99:1). These ligands are also useful for domino conjugate addition followed by enolate trapping with imine and aldehyde.

We synthesized nine quaternary ammonium compounds (QUATs) starting from phenylalanine, N-alkyl-N,N-dimethyl-(1-hydroxy-3-phenylpropyl)-2-ammonium bromides, which were prepared as optically pure substances. Five compounds were prepared as S-enantiomers and four compounds as R-enantiomers. These compounds were evaluated by their activities against bacteria and fungi. Three microbial strains were used in the study: the gram-negative bacteria Escherichia coli, the gram-positive bacteria Staphylococcus aureus and the fungi Candida albicans. The activities were expressed as minimum bactericidal or fungicidal concentrations (MBC). The most active compounds were (2S)-N-tetradecyl-N,N-dimethyl-(1-hydroxy-3-phenylpropyl)-2-ammonium bromide and (2R)-N-tetradecyl-N,N-dimethyl-(1-hydroxy-3-phenylpropyl)-2-ammonium bromide, with MBC values exceeding those of commercial benzalkoniumbromide (BAB) used as standard. The relationships between structure and biological activity of the tested QUATs were quantified by the bilinear model (QSAR) and are discussed.

The compositions of regioisomeric mixtures of tricarbonyliron complexes of 2-methyltropone (1a,b), 3-methyltropone (2a,b) and 2,6-dimethyltropone (3a,b) are studied and compared with the results of ab initio computations. The structures, frontier orbitals, and population analysis are evaluated by means of density functional theory. The thermodynamic and kinetic parameters of regioisomerizations are determined using dynamic 1H NMR technique. The influence of methyl-substituent(s) on the equilibrium ratio of regioisomers resulting from the haptotropic rearrangement is discussed. Significant differences in the reactivity of C-protonized methyl- and dimethyl-substituted tricarbonyl(tropone)iron complexes 4–6 in nucleophilic additions and corresponding O-trimethylsilylated complexes 7–9 in [3+2] cycloadditions are explained in terms of electronic and steric effects of the methyl group(s). Various hydroazulenone cycloadducts of tricarbonyl(η4-2,6-dimethyltropone)iron 3a,b have been prepared by stereoselective [3+2] cycloaddition with Fp-reagents 12–14 and characterized. Formerly proposed mechanism of [3+2] cycloaddition was approved.

The effect of microwave irradiation on the reactions of 2-[3-(trifluoromethyl)phenyl]-4-R1-furo[3,2-b]pyrrole-5-carboxhydrazides 1 with 5-arylfuran-2-carboxaldehydes 2, thiophene-2-carboxaldehyde (3) and methyl 2-formylfuro[3,2-b]pyrrole-5-carboxylates 4 has been studied. Reactions of 1 with formic and acetic acid, respectively, led to acylhydrazides 9a–c. Reaction of 1a with 4-substituted 1,3-oxazol-5(4H)-one 10 led to imidazole derivative 13. 1,2,4-Triazole-3-thiones 15a,b were synthesized by two-step reaction of 1a with potassium isothiocyanate and phenyl isothiocyanate, respectively, and subsequent base-catalyzed cyclization of thiosemicarbazides 14a,b. Pyrazole 16 was prepared by reaction of 1a with pentane-2,4-dione.

The reactions of substituted furo[3,2-b]pyrrole-5-carboxhydrazides 1 with 5-arylfuran-2-carboxaldehydes 2, 4,5-disubstituted furan-2-carboxaldehydes 3 and thiophene-2-carboxaldehyde 4 has been studied. The advantage of microwave irradiation on some of these reactions was reflected in the reduced reaction time and increased yields. Reactions of 1 with 4-substituted 1,3-oxazol-5(4H)-ones 11 led to diacylhydrazines 13 or to imidazole derivatives 14 depending on the temperature. 1,2,4-Triazole-3-thione 17 was synthesized by two-step reaction of 1 with phenylisothiocyanate and subsequent base-catalyzed cyclization of thiosemicarbazide 16. The effects of hydrazones 5–10 on inhibition of photosynthetic electron transport in spinach chloroplasts and chlorophyll content in the antialgal suspensions of Chlorella vulgaris were investigated.

The kinetic and thermodynamic parameters for regioisomerisation of 2-methyl- and 2,6-dimethyl-derivatives of tricarbonyl[η 4 -tropone]iron complexes have been studied by 1 H NMR spectrometry over a range of 40 °C. Regioisomerisation of these complexes proceeds by an intramolecular first-order process and results in the almost complete conversion of the less stable complexes ( 4 , 8 ) to more stable regioisomers ( 1 , 5 ). The activation energies and half lifes for the conversion ( 4 → 1 ) and ( 8 → 5 ) were found to be Δ G # =92 kJ mol −1 ; τ 1/2 =12.8 h, and Δ G # =107 kJ mol −1 ; τ 1/2 =26.8 h, respectively, at 23 °C. Complex 1 reacts with (1R,2S,5R)-menthol in sulphuric acid solution, followed by neutralisation with sodium carbonate to give a separable mixture of diastereomeric tricarbonyl[(2,3,4,5-η)-(1R ′ ,2S ′ ,5R ′ )-6-menthyloxy-2-methyltropone]iron complexes, 9 and 10 . The corresponding dimethylated complex 5 fails to react under these conditions.

The diastereoselectivity of [3+2] cycloaddition of tricarbonyl[(4,5,6,7-η)-2-methyltropone]iron (2) with an E,Z isomeric mixture of η1-(crotyl)Fp (4E/4Z) [Fp: C5H5Fe(CO)2 or CpFe(CO)2] has been studied. By this cyclopentaanulation, four stereogenic centres are formed. The reaction occurs regioselectively and stereoselectively. The relative configurations of the cycloadducts 5a, 5b and 5c were assigned on the basis of 2D and NOE NMR experiments. A mechanism for the stereoselective [3+2] cycloaddition has been proposed. The selectivity of the cycloaddition depends on the difference in steric discrimination approaches of the η1-(crotyl)Fp 4E/4Z to the tricarbonyl[(3,4,5,6,7-η)-1-trimethylsilyloxy-2-methyltropylium]iron 3 (repulsion of the methyl and methylene groups of 4 and the planar skeleton of 3) and also upon the isomeric structure (E or Z) of the η1-(crotyl)Fp reactant. The geometrical isomerism of the reagent (4E/4Z) is preserved in the products 5a–c.

In this study, we demonstrate the synthesis of the [Al13O4(OH)24(H2O)12]7+ Keggin e-Al13 ion by a mechanochemical reaction between [Al(H2O)6]Cl3 and (NH4)2CO3 reactants. Five grams of the starting mixture corresponding to a molar ratio of (NH4)2CO3/[Al(H2O)6]Cl3 = 0.45:2, 1:2, 1.5:2, 2:2, 2.25:2, 2.55:2 and 3:2 was milled for 5 min. The existence of e-Al13 was observed at molar ratios of (NH4)2CO3/[Al(H2O)6]Cl3 = 2:2 and higher. Our results show that more than 50% mass of Al from a starting [Al(H2O)6]Cl3 was bonded to the polymeric [Al13O4(OH)24(H2O)12]7+ ionic form at a molar ratio of 2.55:2.

2,2′-Diiodo-1,1′-binaphthalene undergoes a tandem Heck reaction with methyl acrylate to afford methyl 2-(7H-dibenzo[c,g]fluoren-7-ylidene)acetate. As a consequence, the target macrocyclic diazene with binaphthalene unit attached via acrylamide linker was prepared by the stepwise building of acrylamide at a binaphthalene moiety, including the Doebner modification of the Knoevenagel condensation, and completed by oxidative macrocyclisation of aniline end-groups. Despite being an equimolar mixture of monomer and dimer, it exhibited remarkable changes in CD spectra due to reversible (E/Z) isomerisation of N=N diazene bonds upon irradiation at 365/465 nm. Although the dimer isomerises from (E) to (Z) isomer 7.4 times faster than the monomer, the latter’s contribution to the change in ellipticity at 307 nm in the photostationary state is 2.4 times greater.

Substituted furopropenoic acids were prepared from appropriate aldehyde under the Doebner’s conditions. Obtained acids were converted to the corresponding azides, which were cyclized by heating in Dowtherm to furopyridones. These compounds were aromatized with phosphorus oxychloride to chloro derivatives of furo[3,2-c]pyridine (Va, Vb). Chloro derivative Vb was reduced with hydrazine hydrate to 2-(4-aminophenyl)furo[3,2-c]pyridine in ethanol and Pd/C as a catalyst. Chloro derivative Va was converted to 4-amino-2-(3-pyridyl)furo[3,2-c]pyridine under the same conditions. The chlorine atom in other chloro derivatives (VIIa, VIIb) was replaced by nucleophilic substitution with alkoxides (sodium ethoxide, propoxide, and isopropoxide) and the corresponding alkoxy derivatives were formed. By reaction of VII with cyclic secondary amines (morpholine, piperidine, and pyrrolidine) 4-substituted furopyridines were prepared.