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Herein, we have disclosed pentafluorophenol as an operative catalyst for synthesizing (spirocyclic) tetrahydro‐β‐carbolines via the Pictet‐Spengler reaction. This straightforward catalytic protocol works under mild conditions resulting indole alkaloids in excellent yield with remarkable functional group tolerance, including late‐stage modifications. This transformation demonstrates a practical and adaptable approach to produce a highly effective gram‐scale synthesis of the natural alkaloid Komavine and enables the synthesis of the commercial drug Tadalafil. [ABSTRACT FROM AUTHOR] more...

An easy atom‐economic methodology for the synthesis of tetrahydro‐β‐carbolino‐spiroindolone/ spiroacenapthylene scaffold in one step from tryptamine and isatin have been done via Pictet‐Spengler Reaction using lemon juice as a biocatalyst system. The reaction is clean and convenient for the synthesis of spiroindolones. The product was separated via easy chromatographic technique (column/flash) and characterized by 1D NMR (1H, 13 C and DEPT) and HRMS analysis. Bio evaluation against four cancer cell lines (MCF‐7, SH‐SY5Y, HepG2 and HEK 293) shows good positive indication of activity for 3 g, 3 h and 3 i. [ABSTRACT FROM AUTHOR] more...

A series of 3',4'‐dihydro‐1'H‐spiro(indoline‐3,2'‐quinolin)‐2‐ones were prepared by the inverse‐electron‐demand aza‐Diels–Alder reaction (Povarov reaction) of imines derived from isatin and substituted anilines, and the electron‐rich alkenes trans‐isoeugenol and 3,4‐dihydro‐2H‐pyran. These compounds were assessed for in vitro antiplasmodial activity against drug‐sensitive and drug‐resistant forms of the P. falciparum parasite. Three compounds derived from 3,4‐dihydro‐2H‐pyran and four compounds derived from trans‐isoeugenol showed antiplasmodial activity in the low micromolar range against the drug‐resistant FCR‐3 strain (1.52–4.20 µM). Only compounds derived from trans‐isoeugenol showed antiplasmodial activity against the drug‐sensitive 3D7 strain (1.31–1.80 µM). [ABSTRACT FROM AUTHOR] more...