Jure Bezenšek

Preparation of Polysubstituted Isochromanes by Addition of ortho-Lithiated Aryloxiranes to Enaminones

The reaction of ortho-lithiated aryloxiranes with various enaminones straightforwardly affords new functionalized isochromanes as mixtures of two epimeric stereoisomers in reasonable to very good yields (50-90%). The two diastereomers, which show a high structural variability, can be easily separated by column chromatography.

Ruthenium complexes as inhibitors of the aldo-keto reductases AKR1C1-1C3.

The human aldo-keto reductases (AKRs) from the 1C subfamily are important targets for the development of new drugs. In this study, we have investigated the possible interactions between the recombinant AKR1C enzymes AKR1C1-AKR1C3 and ruthenium(II) complexes; in particular, we were interested in the potential inhibitory actions. Five novel ruthenium complexes (1a, 1b, 2a, 2b, 2c), two precursor ruthenium compounds (P1, P2), and three ligands (a, b, c) were prepared and included in this study. Two different types of novel ruthenium(II) complexes were synthesized. First, bearing the sulphur macrocycle [9]aneS3, S-bonded dimethylsulphoxide (dmso-S), and an N,N-donor ligand, with the general formula of [Ru([9]aneS3)(dmso)(N,N-ligand)](PF6)2 (1a, 1b), and second, with the general formula of [(η(6)-p-cymene)RuCl(N,N-ligand)]Cl (2a, 2b, 2c). All of these synthesized compounds were characterized by high-resolution NMR spectroscopy, X-ray crystallography (compounds a, b, c, 1a, 1b) and other standard physicochemical methods. To evaluate the potential inhibitory actions of these compounds on the AKR1C enzymes, we followed enzymatically catalyzed oxidation of the substrate 1-acenaphthenol by NAD(+) in the absence and presence of various micromolar concentrations of the individual compounds. Among 10 compounds, one ruthenium complex (2b) and two precursor ruthenium compounds (P1, P2) inhibited all three AKR1C enzymes, and one ruthenium complex (2a) inhibited only AKR1C3. Ligands a, b and c revealed no inhibition of the AKR1C enzymes. All four of the active compounds showed multiple binding with the AKR1C enzymes that was characterized by an initial instantaneous inhibition followed by a slow quasi-irreversible step. To the best of our knowledge, this is the first study that has examined interactions between these AKR1C enzymes and ruthenium(II) complexes.

SYNTHESIS OF 8-HYDROXYIMIDAZO[1,2-a]PYRIDINE-2-CARBOXYLIC ACID AND ITS DERIVATIVES

Two new imidazo[1,2-a]pyridines, 8-hydroxyimidazo[1,2-a]pyridine-2-carboxylic acid (4) and ethyl 8-hydroxyimidazo[1,2-a]pyridine-2-carboxylate (6) were prepared via cyclization of 2-aminopyridin-3-ol (1) with bromopyruvic acid (2) and ethyl bromopyruvate (3), respectively. 8-Hydroxyimidazo[l,2-a]-pyridine-2-carboxylic acid (4) was successfully coupled with various amino acid derivatives via its active ester intermediate into the corresponding amides 22-27. O-protected ethyl 8-hydroxyimidazo[l,2-a]pyridine-2-carboxylate 11 was transformed into its hydrazide 13, acyl azide 14, and amide 15 derivatives.

A Simple Metal-free Synthesis of 2,4,5-Trisubstituted Pyridines and Pyridine N-Oxides by [2+2] Cycloaddition of Enaminones to Propyne Iminium Salts

Herein a simple one-pot metal-free synthesis of 2,4,5-trisubstituted pyridines and pyridine Noxides by [2+2] cycloaddition of enaminones, which are prepared in situ from alkyl, aryl and heteroaryl methyl ketones using N,N-dimethylformamide dimethyl acetal (DMFDMA), and propyne iminium salts as electron-poor acetylenes, is described. Graphical Abstract A Simple Metal-free Synthesis of 2,4,5-Trisubstituted Pyridines and Pyridine N-Oxides by [2+2] Cycloaddition of Enaminones to Propyne Iminium Salts

A simple synthesis of 4-aroyl-5-methyl-1H-imidazol-2(3H)-one derivatives (Enoxymone analogues) from aryl methyl ketones via enaminones

Aryl methyl ketones 1a-e gave with N,N-dimethylacetamide dimethylacetal (DMADMA) ( E)-1aryl-3-(dimethylamino)-but-2-en-1-ones 2a-e. Substitution of the N,N-(dimethylamino) group in the reaction with ammonium acetate afforded the cor responding ( Z)-3-amino-1-aryl-but-2-en-1ones 3a-e. In the reaction of 3a-e with diethyl azodicarboxylate intermediates 4a-e were formed, which were, in most cases without isolation, cycliz ed into ethyl (5-aroyl-4-methyl-2-oxo-2,3dihydro-1H-imidazol-1-yl)carbamates 5a-e. Hydrolysis of the ester group, followed by the decarboxylation and deamination of intermediates 6a-c,e produced 4-aroyl-5-methyl-1 Himidazol-2(3H)-ones 7a-c,e.