Modular Divergent Synthesis of Functionalized Indoles via TFA-Promoted Amino-Claisen Rearrangement at Room Temperature.

A conceptually novel approach for the modular and divergent synthesis of highly functionalized indoles via trifluoroacetic acid-promoted amino-Claisen rearrangement is reported. This metal-free protocol could be performed at room temperature with wide functional group tolerance. The substitution type of the resultant indoles could be easily adjusted by the variation of the starting propargyl amines. The resultant products could be easily transformed into different value-added indole derivatives with simple experimental operations.