Design and Synthesis of New Quinoline Linked to Pyranotriazolopyrimidines Conjugates as Novel Targets to Discover Promising Anti-SARS-COV-2

Abstract

Simple one-pot synthesis of 2-aminopyranoquinoline-3-carbonitriles 2a-d at room temperature from available 8-hydroxyquinaldine, malononitrile, and substituted aromatic aldehydes was realized. Compounds 2a-d were converted into imino ethers 3a-d, condensed with a series of hydrazide under microwave irradiation to yield novel pyranotriazolopyrimidines fused to quinoline 4a-f. Compound 4c, with a cyanomethyl group, was treated with some salicylic arylaldehydes to give the corresponding new pyranotriazolopyrimidine-chromen hybrids 5a-c in good yields. Finally a new series of arylidenes linked to triazolopyrimidopyrano[3,2-h]quinoline 6a-h were designed and synthesized by the reaction of 4a,c, both bearing a cyanomethyl group, with a series of arylaldehydes. The structures of all the compounds were evidenced by 1 H/ 13 C NMR, IR, and ESI-HRMS. The present study focuses also to predict the theoretical assembly of the COVID-19 protease (SARS-CoV-2 M pro ) and to find in advance whether this protein can be targeted by the compounds 4c, 4f, 5a-c and 6a-h thus synthesized. The docking scores of these compounds were compared to that of the co-crystallized native ligand inhibitor (N3) used as a reference standard.