Dragana Stevanović

Sulfur-containing ferrocenyl alcohols and oximes: new promising antistaphylococcal agents.

A small library containing four different series of new ferrocene derivatives, 2‐(alkylsulfanyl)‐1‐ferrocenylethan‐1‐ols, 3‐(alkylsulfanyl)‐1‐ferrocenylpropan‐1‐ols, (E)‐ and (Z)‐2‐(alkylsulfanyl)‐1‐ferrocenylethan‐1‐one oximes, and (E)‐ and (Z)‐3‐(alkylsulfanyl)‐1‐ferrocenylpropan‐1‐one oximes (36 different compounds in total) was synthesized starting from ferrocene and the corresponding sulfanyl acids. All compounds were spectrally (IR and NMR) and electrochemically characterized. In general, the obtained compounds were found to exhibit very strong antimicrobial activities (broth microdilution assay) against the tested microorganisms (six common human pathogens). For the majority of the tested compounds, the determined MIC values were either under the 10 μg/ml MIC limit recognized to delimit efficient antimicrobials or were comparable to/lower than those of the used positive controls (tetracycline/nystatin). The most susceptible organism was found to be Staphylococcus aureus with MIC values even reaching 0.001 μg/ml. The presence of CH(OH)(CH2)nS and CH(NOH)(CH2)nS (n=1 or 2) structural fragments seems to be essential for the observed strong activity (introduction of hydroxyimino and alcohol functionalities, instead of the keto function, resulted in a more than 105‐fold increase in antistaphylococcal activity in some instances). Nevertheless, a possible influence of the ferrocenyl‐core redox chemistry (Fe2+/Fe3+) should not be disregarded. The studied alcohols exhibited a reversible one‐electron redox couple at almost the same position as ferrocene, while the hydroxyimino group conjugated with cyclopentadienyl ring considerably shifted the redox potential of the ferrocene unit in oximes.

Electrochemical bromochlorination of peracetylated glycals

Peracetylated glycals-3,4,5-tri-O-acetyl-D-glucal (1a), 3,4,5-tri-O-acetyl-D-galactal (1b) and 3,4-di-O-acetyl-6-deoxy-L-glucal (1c)-have been bromochlorinated by a suitable halogenating agent, generated electrochemically from a mixture of bromides and chlorides in dichloromethane. The reaction was performed in two ways: (i) by a constant current electrolysis (2Fmol(-1)) of bromides and substrates in a milieu containing an excess of chlorides (Br(θ)/1/Cl(θ)=1:1:6.8) and (ii) by anodic generation of free chlorine from chlorides (2Fmol(-1)) and subsequent addition of bromides and substrates in a ratio Br(θ)/1=1:1. The corresponding 2-bromo-2-deoxy-glycopyranosyl chlorides were obtained in high yields.

The palladium(II) complex of N,N-diethyl-1-ferrocenyl-3-thiabutanamine: synthesis, solution and solid state structure and catalytic activity in Suzuki–Miyaura reaction

In this paper we wish to present the first results on the synthesis of N,N-diethyl-1-ferrocenyl-3-thiabutanamine, its coordination with palladium(II), the complete characterization of the thus obtained complex (including single crystal X-ray analysis for the complex in two polymorphic forms) and screening of its catalytic activity in Suzuki–Miyaura coupling of phenylboronic acid with several aryl bromides. The complex, either purified and then added to the reaction mixture or generated in situ, proved to be an excellent precatalyst in Suzuki–Miyaura coupling. The chemical behavior of the complex in solution was assessed by detailed NMR analyses and cyclic voltammetry measurements which allowed us to draw a number of mechanistic conclusions.

1-Ferrocenyl-3-(4-methyl­anilino)propan-1-one

In the title ferrocene derivative, [Fe(C5H5)(C15H16NO)], the dihedral angle between the best planes of the benzene and the substituted cyclopentadienyl ring is 83.4 (1)°. The presence of a methyl substituent in the para position of the aniline group does not alter the crystal packing compared to that of 3-anilino-1-ferrocenylpropan-1-one [Leka et al. (2012 ▶). Acta Cryst. E68, m229]. The molecules are connected into centrosymmetric dimers via N—H⋯O hydrogen bonds. In addition, C—H⋯O and C—H⋯N contacts stabilize the crystal packing.

3-Anilino-1-ferrocenylpropan-1-one

In the title ferrocene derivative, [Fe(C5H5)(C14H14NO)], the dihedral angle between the mean planes of the phenyl ring and the substituted cyclopentadienyl ring is 84.4 (1)°. The molecules are connected into centrosymmetric dimers via N—H⋯O hydrogen bonds. In addition, C—H⋯O and C—H⋯N contacts stabilize the crystal packing.

A new polymorph of 1-ferrocenyl-3-(3-nitroanilino)propan-1-one.

Recrystallization of the title compound, [Fe(C(5)H(5))(C(14)H(13)N(2)O(3))], from a mixture of n-hexane and dichloromethane gave the new polymorph, denoted (I), which crystallizes in the same space group (P1) as the previously reported structure, denoted (II). The Fe-C distances in (I) range from 2.015 (3) to 2.048 (2) Å and the average value of the C-C bond lengths in the two cyclopentadienyl (Cp) rings is 1.403 (13) Å. As indicated by the smallest C-Cg1-Cg2-C torsion angle of 1.4° (Cg1 and Cg2 are the centroids of the two Cp rings), the orientation of the Cp rings in (I) is more eclipsed than in the case of (II), for which the value was 15.3°. Despite the pronounced conformational similarity between (I) and (II), the formation of self-complementary N-H···O hydrogen-bonded dimers represents the only structural motif common to the two polymorphs. In the extended structure, molecules of (I) utilize C-H···O hydrogen bonds and, unlike (II), an extensive set of intermolecular C-H···π interactions. Fingerprint plots based on Hirshfeld surfaces are used to compare the packing of the two polymorphs.

Synthesis of ferrocene-containing six-membered cyclic ureas via α-ferrocenyl carbocations

A series of ferrocene-containing six-membered cyclic ureas (1-aryl-4-ferrocenyl-3-phenyltetrahydropyrimidin-2(1H)-ones) was synthesized (in high-to-excellent yields) by reacting the corresponding aminopropanols with phenyl isocyanate and the subsequent intramolecular cyclization of the thus obtained β-hydroxy ureas (prompted by acetic acid), via an α-ferrocenyl carbocation.

Essential-Oil Constituents and Alkanes of Cephalaria ambrosioides Roem. & Schult. (Family Caprifoliaceae, Subfamily Dipsacaceae) and (Chemo)taxonomic Discernment of the Subfamilies Dipsacaceae and Morinaceae.

Herein, the results of the first study of the volatile and alkane profiles of Cephalaria ambrosioides Roem. & Schult. (Caprifoliaceae, subfamily Dipsacaceae) were reported. The GC‐FID and GC/MS analyses of the essential oils hydrodistilled from leaves and stems (CA1) and flowers (CA2) of C. ambrosioides allowed the identification of 284 different components. The main compounds of the studied oil samples were palmitic acid (24.3 and 32.5% for CA1 and CA2, resp.), hexahydrofarnesyl acetone (1.4 and 10.8% for CA1 and CA2, resp.), (Z)‐hex‐3‐en‐1‐ol (7.0 and <0.1% for CA1 and CA2, resp.), and linoleic acid (1.9 and 6.5% for CA1 and CA2, resp.). Essential‐oil compositional data of selected plant species belonging to the Dipsacaceae (15) and Morinaceae (2) subfamilies were used to resolve taxonomical ambiguities regarding the genus Cephalaria and its infrageneric relations, especially concerning the subfamily Morinaceae (formerly a genus within Dipsacaceae). The results of multivariate statistical analyses (25 different essential‐oil samples) supported the exclusion of Morina species from the Dipsacaceae subfamily. The relative abundances of alkanes from n‐, iso‐, and anteiso‐series followed a (distorted) Gaussian‐like distribution and suggested that the biosyntheses of n‐ and branched alkanes in C. ambrosioides are possibly not controlled by the same elongase. Also, the obtained results suggested that there was a difference in the biosynthesis/accumulation of alkanes in the vegetative and reproductive parts of C. ambrosioides.

4-[(4-Methyl-phen-yl)sulfan-yl]butan-2-one.

In the title compound, C11H14OS, all non-H atoms are essentially coplanar, with a mean deviation of 0.023 Å. In the crystal, centrosymmetrically related molecules are weakly connected into dimers by pairs of C—H⋯O interactions. The dimers are further linked along the a axis by weak C—H⋯π and C—H⋯S interactions.

3-(3-Acetyl­anilino)-1-ferrocenylpropan-1-one

The title ferrocene-containing Mannich base, [Fe(C5H5)(C16H16NO2)], crystallizes with two independent molecules (A and B) in the asymmetric unit. Molecules A and B have similar conformations. The dihedral angles between the best planes of the benzene and substituted cyclopentadienyl rings are 88.59 (9) and 84.39 (10)° in A and B, respectively. In the crystal, the independent molecules form centrosymmetric dimers via corresponding N—H⋯O hydrogen bonds. The dimers further arrange via C—H⋯π and C—H⋯O interactions. There are no significant interactions between the A and B molecules.