Efficient solid-phase synthesis of 2,3-substituted indoles

The development of the solid-phase version of the modified Madelung indole synthesis is reported. The chemistry was initiated with the reductive amination of Bal resin using an ortho substituted aniline. The resin bound aniline was acylated with a variety of acid chlorides followed by cyclization with base to provide the desired indole after TFA-promoted cleavage from the resin.