Chemistry of Indoles Carrying a Basic Function, Part 3¹ Synthesis of Spiro[cyclopropane‐1,3′[3<i>H</i>]indol]‐2′(1′<i>H</i>)‐ones with Antihypoxic Effects

Abstract

Hydroxyindolones (1-6, 15-16) were transformed into isatinylidenes (7, 9-13, 17-19) by dehydration with 4-toluenesulfonic acid. The dimer-type compounds (14, 20) were also isolated in a few cases. The obtained isatinylidenes were transformed into 3-spiro-cyclopropane-oxindoles (21-32) with dimethyloxosulfonium methylide. Compound 22 shows protective effects against hypobaric hypoxia and triethyltin induced brain edema.