Development of novel methods for synthesis of heterocyclic compounds catalyzed by transition metals in fluorinated alcohols

New possibilities for catalytic syntheses of lactone derivatives and nitrogen-containing heterocyclic compounds in fluorinated alcohols are described. The cationic Rh (1) catalyst in fluorinated alcohol solvents (hexafluoroisopropanol: HFIP, trifluoroethanol: TFE) brought about not only mild cycloaddition reactions of ester-tethered compounds but also a facile formation of indole derivatives by the aromatic amino-Claisen rearrangement of N-propargyl aniline derivatives. The use of HFIP as an additive exerted a remarkable effect on the Pictet-Spengler reaction catalyzed by the fluorinated surfactant-combined Bronsted acid catalyst in water.