Synthesis of novel N1 functionalized diazepinone analogues via a base-mediated C-N cross coupling reaction as reverse transcriptase inhibitors: theoretical and experimental investigations

Abstract

The sodium hydrogen orthophosphate (Na₂HPO₄) base was utilized in a stereospecific C-N coupling reaction to synthesize a novel series of nevirapine analogues in two-step reactions. This base is moisture tolerant, commercially available and makes the protocol cheap and energy efficient, with broad substrate tolerance, leading to the formation of cyclopropyl, cyclobutyl, cyclopentyl and propane-engrafted dipyridodiazepinone derivatives in good yield with a higher atom economy >70%. All the synthesized analogues were examined for reverse transcriptase inhibitory activity and compared with the reference drug nevirapine. Further in silico analysis via molecular docking, molecular simulation, and ADMET studies revealed that compounds 5a and 5b showed prominent inhibitory activity against reverse transcriptase. Additionally, isothermal titration calorimetry experiments were performed to determine the thermodynamic parameters of the interaction between nevirapine analogues and human serum albumin. The binding affinity of 5b in the order of 10² indicates that the synthesized analogues can be easily carried out into the bloodstream. These findings demonstrate that nevirapine analogous are promising reverse transcriptase inhibitors for the therapeutic treatment of HIV infection, offering a new avenue for the less toxic and more effective development of anti-retroviral drugs.

Fig. 1. Representative bioactive diazepine derivatives.

Fig. 2. Preparation of designed compounds in a two-step synthetic process via C–N coupling.

Fig. 3. Feature mapping analysis of 5(a–h) using structure-based pharmacophore modelling (green colour: HBA, cyan colour: HY, and pink colour: HBD).

Scheme 1. Synthesis of carboxamide 3(a–b).

Scheme 2. Substrate scope for the synthesis of novel dipyridodiazepinone derivatives.

Scheme 3. (a–c) Control experiments.

Fig. 4. Inhibitory effect of synthesized analogues on the HIV-RT enzyme.

Fig. 5. Binding interactions of 5a, 5b and nevirapine with the active binding pockets of HIV-I reverse transcriptase enzyme.

Fig. 6. (a) RMSD analysis of 5a, (b) RMSF analysis of 5a, (c) binding interaction analysis of 5a with the HIV-I reverse transcriptase, and (d) 2D-contact information of 5a with the HIV-I reverse transcriptase enzyme.

Fig. 7. (a) RMSD analysis of 5b, (b) RMSF analysis of 5b, (c) binding interaction analysis of 5b with the HIV-I reverse transcriptase, and (d) 2D-contact information of 5b with the HIV-I reverse transcriptase enzyme.

Fig. 8. Mechanism for the inhibition of reverse transcriptase via synthesized analogues.

Fig. 9. ITC profiles for nevirapine and its analogues (5a and 5b) with HSA at 298 K.

Fig. 10. Fluorescence quenching titration spectra of HSA with increasing concentrations of nevirapine (a), compound 5a (b), and compound 5b (c). Lower panel shows the Stern–Volmer plots of the respective compounds.