Preparation and antiplasmodial activity of 3',4'‐dihydro‐1'H‐spiro(indoline‐3,2'‐quinolin)‐2‐ones

: 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).