SYNTHESIS AND PROPERTIES OF NEW 1-HYDRAZINOCARBONYLMETHYL-7-BROMO-5-PHENYL-3-ARYLYDENE-1,2-DIHYDRO-3H-1,4-BENZODIAZEPIN-2-ONES
Authors: Bachinsky S. Yu. , Burenkova N. O. , Andronati S. A. , Ishkov Yu. V. 
Published: November 2023

It is known that 1,4-benzodiazepines have neurotropic properties. Previously, we synthesized a series of 3-arylidene-1,2-dihydro-3H-1,4-benzdiazepin-2-ones 11-18 and showed that they exhibit significant analgesic activity. They also show significant affinity for central benzodiazepine receptors and TSPO receptors CNS. With this in mind, we have previously modified the series of 3-arylidene-1,2-dihydro-3H-1,4-benzodiazepin-2-ones by alkylation of 3-arylidene-1,2-dihydro-3H-1,4-benzodiazepin-2-ones with monobromoacetic acid methyl ester to the first position of the 1,4-diazepine ring to obtain 1-methoxycarbonylmethyl-7-bromo-5-phenyl-3-arylidene-1,2-dihydro-3H-1,4-benzodiazepin-2-ones 19-26, which showed pronounced analgesic activity.
The aim of this work is to synthesize and study the affinity for CBR and TSPO receptors 1-hydrazinocarbonylmethyl-7-bromo-5-phenyl-3-arylidene-1,2-dihydro-3H-1,4-benzodiazepin-2-ones 27-31, which have not been previously described in the literature. Compounds 27-31 were synthesized as a result of the reaction of 1-methoxycarbonylmethyl-7-bromo-5-phenyl-3-arylidene-1,2-dihydro-3H-1,4-benzodiazepin-2-ones 19-26 with hydrazine hydrate while stirring the components in ethanol. The yields of the reaction products were 65-92%. It was shown that the hydrazinolysis technique used provides high yields of the target compounds. The structure of the synthesized compounds was confirmed by mass spectrometry and 1H NMR spectroscopy.
The affinity of the synthesized compounds to the central benzodiazepine receptors CNS (CBR) and TSPO receptors CNS was studied. The affinity of compounds 27-31 was determined in vitro by radioligand analysis by their ability to displace the commercial radioligands [3H] flumazenil and [3H]PK11195 from their specific binding sites in the GABAA receptor complex and TSPO receptors of the synaptic and the mitochondrial fractions of the rat brain membranes, respectively.
Compound 27 displaces the commercial [3H]flumazenil radioligand from its specific binding sites in the GABAA receptor complex by 80.1%, and simultaneously exhibits a very low affinity for TSPO receptors. Derivative 27 is the most potent CBR ligand among the investigated compounds and it is a promising compound for pharmacological research.
It has been established that in the synthesized series of 3-fluorobenzylidene derivatives, varying the position of the fluorine atom in the benzylidene fragment leads to change affinity for TSPO receptors. It has been established that the para- position of the fluorine atom in the 3-benzylidene radical of the 1,4-benzodiazepin-2-one molecule is the most important descriptor that determines their affinity for the TSPO receptors.
These data agree with the data available in the literature on the effect of the position of chlorine and bromine atoms in the 3-benzylidene radical of the 1,4-benzodiazepin-2-one molecule on the affinity for the TSPO receptors. It was found that the main structural fragment that determines the affinity of binding of 3-benzylidene derivatives to TSPO receptors is the presence of electronegative substituents in the para-position of the benzylidene fragment:
para–Hal>>оrtho–Hal>meta–Hal (affinity for TSPO)
(Hal= Br, F)
Thus, the expediency of further study of this class of compounds is shown.