On Water Pictet‐Spengler Reaction of Tryptophan followed by Buchwald Coupling for the Synthesis of Natural Products Stellarines A, B and β‐Carboline Derivatives: Their Molecular Docking against SARS‐CoV‐2 MPro

Abstract Natural products are versatile moiety in the drug discovery and development, however, their synthesis being one of the major challenges in this field. In this regard, an environment friendly synthesis of 1‐benzoyl‐9 H ‐pyrido[3,4‐ b ] indole‐3‐carboxamide β‐carboline derivatives has been reported via Pictet‐Spengler reaction of tryptophan methyl ester with 2‐oxoaldehydes in water as solvent. Natural products Stellarines A and Stellarines B having anti‐inflammatory activity against i NOS inhibition (IC50 value of 19.3 and 18.6 μM) isolated from the root of Stellaria dichotoma L. var. lanceolata Bunge were also synthesized from β ‐carboline derivatives using amidation followed by Buchwald coupling. The synthetic strategy has advantage of using non toxic and inexpensive materials for producing excellent yields. These functionalized β‐ carboline carboxamide derivatives have been evaluated against SARS‐CoV‐2 M pro (7BQY) using molecular docking studies.