Synthesis, Cytotoxicity and Docking Simulation of Novel Annulated Dihydroisoquinoline Heterocycles

Objective: Coupling of ethyl 2-(6,7-dimethoxy-3,4-dihydroisoquinolin-1-yl)acetate 2 with diazotized anilines in ethanol in the presence of sodium acetate yielded 2-(2-arylhydrazono)-2-(6,7- dimethoxy-3,4-dihydroisoquinolin-1-yl)acetate (4a-f). Methods: Treatment of 2 with α-bromoketones 6a-f in dry benzene at reflux gave the corresponding isoquinolinium bromides 7a-f. Refluxing of each of the salts 7a-f in dry benzene and in the presence of triethylamine yielded 2-arylpyrrolo-[2,1-a]isoquinoline structures 8a-f, that converted to ethyl (E)-8,9- dimethoxy-3-(phenyldiazen-yl)-2-(aryl)-5,6-dihydropyrrolo[2,1-a]isoquinoline-1-carboxylate (9a-f) upon treatment with diazotized anilines 3 in ethanol in the presence of sodium acetate. Results and Conclusion: Cytotoxic assay was performed for in vitro antitumor screening against caucasian breast adenocarcinoma (MCF7), hepatocellular carcinoma (HepG2) and colorectal carcinoma (HCT-116) cell lines. The results were compared with the standard anticancer drug (doxorubicin). Molecular docking using MOE 2014.09 software was carried out for the most potent compound 4d, which showed the highest binding affinity towards the four tested proteins and thus initiated apoptosis of cancer cells.