A New Reactive Ketenaminal: Synthesis, Coupling Reaction, Tautomeric Study, Docking and Antimicrobial Evaluation of the Products

Domino synthesis of functionalized pyridine carboxylates under gallium catalysis: Unravelling the reaction pathway and the role of the nitrogen source counter anion

The catalytic potential of various metal Lewis acid catalysts have been assessed to derive a high-yielding, multi-component domino synthesis of functionalized pyridines from (E)-3-(dimethylamino)-1-aryl/heteroaryl-prop-2-en-1-ones, 1,3-dicarbonyl compounds, and an ammonium salt (as the nitrogen precursor). Amongst the various metal halides, tetrafluoroborates, perchlorates, and triflates used as the catalyst GaI3 proved to be the most effective. The mechanistic course of the most plausible pathway has been outlined as the intermediate formation of imine/enamine by the reaction of the 1,3-dicarbonyl compound with ammonia (liberated in situ from the ammonium salt used as the nitrogen source), which participates in the domino nucleophilic Michael reaction to the (2E)-3-(dimethylamino)-1-aryl/hetroarylprop-2-en-1-one by its active methylene carbon through its enamine form followed by intramolecular cyclization and aromatization. The effect of different ammonium salts as the nitrogen source has been investigated and NH4OAc was found to be best. The influence of the acetate counter anion of NH4OAc on the progress of the reaction was studied and its specific role in the cyclization and subsequent aromatization has been revealed. This work offers distinct advantages compared to the literature reported methodologies on the count of several green index parameters.

Synthesis of a new series of pyrazolo[1,5-a]pyrimidines as CDK2 inhibitors and anti-leukemia

Based on the structural study of previously known CDK2 inhibitors, a new series of pyrazolo[1,5-a]pyrimidine derivatives was designed and synthesized. The target compounds were biologically assessed as potent CDK2 inhibitors and promising anti-leukemia hits. The 7-(4-Bromo-phenyl)-3-(3-chloro/2-chloro-phenylazo)-pyrazolo[1,5-a]pyrimidin-2-ylamines 5 h and 5i revealed the best CDK2 inhibitory activity with comparable potency (IC₅₀ = 22 and 24 nM, respectively) to that of dinaciclib (IC₅₀ = 18 nM). Additionally, both analogues showed potent activities against CDK1, CDK5 and CDK9 at nanomolar concentrations (IC₅₀ = 28-80 nM). The anti-leukemia screening of the target compounds showed strong to moderate cytotoxicity against the used leukemia cell lines (MOLT-4 and HL-60). Compound 5 h inhibited MOLT-4 and HL-60 by 1.4 and 2.3 folds (IC₅₀ = 0.93 and 0.80 µM), respectively, compared to dinaciclib (IC₅₀ = 1.30 and 1.84 µM). Furthermore, compound 5i was comparable to dinaciclib against MOLT-4 and exhibited twice its activity against HL-60. Besides, the cytotoxicity of the promising analogues on normal human blood cells indicated the safety of 5h and 5i as compared to the reference dinaciclib. The pharmacokinetic properties of 5h and 5i were predicted using ADME calculations revealing good oral bioavailability and high GI absorption. The molecular docking simulations indicated, as expected, that the dinaciclib analogues can well-accommodate the CDK2 binding site, forming a variety of interactions.

Synthesis of antimicrobial azoloazines and molecular docking for inhibiting COVID-19

Diverse new azoloazines were synthesized from the reaction of fluorinated hydrazonoyl chlorides with heterocyclic thiones, 1,8-diaminonaphthalene, ketene aminal derivatives, and 4-amino-5-triflouromethyl-1,2,4-triazole-2-thiol. The mechanistic pathways and the structures of all synthesized derivatives were discussed and assured based on the available spectral data. The synthesized azoloazine derivatives were evaluated for their antifungal and antibacterial activities through zone of inhibition measurement. The results revealed promising antifungal activities for compounds 4, 5, 17a,b, 19, and 25 against the pathogenic fungal strains used; Aspergillus flavus and Candida albicans compared to ketoconazole. In addition, compounds 4, 5, 19, and 25 showed moderate antibacterial activities against most tested bacterial strains. Molecular docking studies of the promising compounds were carried out on leucyl-tRNA synthetase active site of Candida albicans, suggesting good binding in the active site forming stable complexes. Moreover, docking of the synthesized compounds was performed on the active site of SARS-CoV-2 3CLpro to predict their potential as a hopeful anti-COVID and to investigate their binding pattern.