Ferrier rearrangement promoted by an electrochemically generated zirconium catalyst.

In situ generated zirconium catalyst from a sacrificial zirconium anode was successfully applied to promote Ferrier rearrangement of 3,4,5-tri-O-acetyl-D-glucal and 6-deoxy-3,4-di-O-acetyl-L-glucal (3,4-di-O-acetyl-L-rhamnal) in the presence of three thiols and eleven thiophenols as nucleophiles. A simple constant current electrolysis (20 mA, 0.4 F mol(-1)) of an acetonitrile solution of lithium perchlorate (0.1 M) containing the corresponding glycal and S-nucleophiles, using a zirconium anode and a platinum cathode resulted in the successful synthesis of the corresponding 2,3-unsaturated peracetylated thioglycosides (with an average anomer ratio α/ß=4.129 in the case of peracetylated D-glucal and 8.740 in the case of L-rhamnal). The same procedure proved to be appropriate in synthesizing dihydropyran derivatives ('C-glycosides') using allyltrimethylsilane as the nucleophile (only 'α-anomers' were obtained). All new compounds were fully characterized by spectral data, whereas single-crystal X-ray analysis was performed for two thioglycosides.

Discovery of anxiolytic 2-ferrocenyl-1,3-thiazolidin-4-ones exerting GABAA receptor interaction via the benzodiazepine-binding site.

Herein, we report on the synthesis, spectral, crystallographic and electrochemical properties of a small library of N-substituted 2-ferrocenyl-1,3-thiazolidin-4-ones, designed as novel GABAA benzodiazepine-binding site ligands. The anxiolytic properties of the title compounds were evaluated in several different in vivo models, whereas the involvement of the GABAA receptor complex in the activity of the most potent compound, 2-ferrocenyl-3-(4-methoxyphenylethyl)-1,3-thiazolidin-4-one, was inferred from experiments with known GABAA-targeting agents. Ligand docking experiments revealed that the high, dose-dependent, anxiolytic activity of the new compounds might be due to their favorable interactions with the benzodiazepine-binding site of the GABAA receptor complex. The incorporation of the ferrocene core and fine tuning of the distance between the thiazolidinone core and an additional aromatic ring were judged to be crucial structural requirements for the observed anxiolytic effect.

1-Ferrocenyl-3-(2-methyl-anilino)propan-1-one.

In the ferrocene-containing Mannich base, [Fe(C(5)H(5))(C(15)H(16)NO)], the dihedral angle between the mean planes of the benzene ring and the substituted cyclo-penta-dienyl ring is 84.63 (7)°. The conformation of the title compound significantly differs from those found in corresponding m-tolyl-amino and p-tolyl-amino derivatives. In the crystal, C-H⋯O inter-actions connect the mol-ecules into chains, which further inter-act by means of C-H⋯π inter-actions. It is noteworthy that the amino H atom is shielded and is not involved in hydrogen bonding.

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.

1-Ferrocenyl-3-(3-fluoro-anilino)propan-1-one.

The title ferrocene derivative, [Fe(C(5)H(5))(C(14)H(13)FNO)], crystallizes in the same space group with similar unit-cell parameters as the derivatives 3-anilino-1-ferrocenylpropan-1-one [Leka et al. (2012 ▶). Acta Cryst. E68, m229] and 1-ferrocenyl-3-(4-methyl-anilino)propan-1-one [Leka et al. (2012 ▶). Acta Cryst. E68, m230]. The dihedral angle between the best planes of the benzene ring and the substituted cyclo-penta-dienyl ring is 83.4 (1)°. The presence of the electronegative fluoro substituent in the meta position of the aniline group does not alter the crystal packing compared to the other two derivatives. 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.