Strychnos alkaloids: total synthesis, characterization, DFT investigations, and molecular docking with AChE, BuChE, and HSA

Abstract

An efficient five steps, the protection-deprotection synthetic a novel synthetic routes to(+/-) noruleine (f)-uleine, are reported starting from tetrahydrocarbazole fused monoalkyl nitrile at C-2 position that is prepared on mul-tigram scale from 2-(3-ethyl-1-oxo-2,3,4,9-tetrahydro-1H-carbazol-2-yl)acetonitrile (1) as well as the key azocino [4,3-b]indole skeleton is constructed via the tetrafluoro-1,4-benzoquinone (TFB)-mediated cyclization of a tet-rahydrocarbazole derivative possessing direct amide synthesis from nitrile. As a result, Total synthesis of nor-uleine and uleine has been developed, which is accomplished in 4 and 5-steps synthesis of the ABCD tetracyclic of the strychnos alkaloids with an overall yield of 44% and 39%, respectively. The DFT computations were per-formed with B3LYP/6-311g(d,p) level to determine inter and intramolecular interactions and reactivity features of the compound 3-6. Also, TD-DFT computations were performed to characterize the electronic absorption spectra of all compounds. Last, the interactions of compounds 3-6 with selected targets AChE, BuChE, and HSA were evaluated in light of the molecular dockings. The bioactivity and drug-likeness scores revealed that com-pound 6 3-6 can be proper candidate for future drug-design studies more than the other compounds.