Heterocyclic Schiff Bases of 3-Aminobenzanthrone and Their Reduced Analogues: Synthesis, Properties and Spectroscopy.

New substituted azomethines of benzanthrone with heterocyclic substituents were synthesized by condensation reaction of 3-aminobenzo[de]anthracen-7-one with appropriate aromatic aldehydes. The resulting imines were reduced with sodium borohydride to the corresponding amines, the luminescence of which is more pronounced in comparison with the initial azomethines. The novel benzanthrone derivatives were characterized by NMR, IR, MS, UV/Vis, and fluorescence spectroscopy. The structure of three dyes was studied by the X-ray single crystal structure analysis. The solvent effect on photophysical behaviors of synthesized imines and amines was investigated. The obtained compounds absorb at 420-525 nm, have relatively large Stokes shifts (up to 150 nm in ethanol), and emit at 500-660 nm. The results testify that emission of the studied compounds is sensitive to the solvent polarity, exhibiting negative fluorosolvatochromism for the synthesized azomethines and positive fluorosolvatochromism for the obtained amines. The results obtained indicate that the synthesized compounds are promising as luminescent dyes.

Synthesis and biological evaluation of 2-(5-methyl-4-phenyl-2-oxopyrrolidin-1-yl)-acetamide stereoisomers as novel positive allosteric modulators of sigma-1 receptor.

Novel positive allosteric modulators of sigma-1 receptor represented by 2-(5-methyl-4-phenyl-2-oxopyrrolidin-1-yl)-acetamide enantiomers were synthesised using an asymmetric Michael addition of 2-nitroprop-1-enylbenzene to diethyl malonate. Following the chromatographic separation of the methyl erythro- and threo-4-nitro-3R- and 3S-phenylpentanoate diastereoisomers, target compounds were obtained by their reductive cyclisation into 5-methyl-4-phenylpyrrolidin-2-one enantiomers and the attachment of the acetamide group to the heterocyclic nitrogen. Experiments with electrically stimulated rat vas deference contractions induced by the PRE-084, an agonist of sigma-1 receptor, showed that (4R,5S)- and (4R,5R)-2-(5-methyl-4-phenyl-2-oxopyrrolidin-1-yl)-acetamides with an R-configuration at the C-4 chiral centre in the 2-pyrrolidone ring were more effective positive allosteric modulators of sigma-1 receptor than were their optical antipodes.