Synthetic route to 4-(2-aminoethyl)-5-hydroxyindole derivatives

In synthetic studies leading to the title compounds, application of the Claisen rearrangement of 5-allyloxyindole was investigated. Almost quantitative yields of Claisen rearrangement product were realized, and a strategy for oxidative cleavage of the allyl double bond to an indole-4-acetaldehyde derivative was developed. A new method for conversion of 2,3-dihydroindoles into indoles was utilized: air oxidation in a strongly basic environment. The Claisen rearrangement of allyloxyindoles is presented as a method having considerable potential utility in synthesis of a variety of polysubstituted indoles.