The Wittig reaction of 1-acetyl-2-methoxy-(1) and 1 -acetyl-2-hydroxyindol-3(2H)-one (2) with stabilized and semistabilized ylides gave predominantly 3-alkylidenedihydroindoles (4), (7), and (13) with (Z)-stereochemistry. When the Wittig reaction was carried out under more drastic conditions, the Wittig products (4) and (7) isomerized to afford 3-alkylindoles (5) and the indol-2-one (8), respectively
Anodic fluorination of various N-acetyl-3-substituted indole derivatives was successfully carried out in Et(4)NF-4HF/MeCN to provide the corresponding trans-2,3-difluoro-2,3-dihydroindoles exclusively or selectively. Treatment of difluorinated products with a base provided monofluoroindole derivatives or monofluoroindoline derivative depending on the substituents at the 3-position. (C) 2010 Elsevier Ltd. All rights reserved.