A Solvent-Involved Synthesis of Etherified Tryptophol Derivatives: Indolization and Condensation in a Single-Stage Flow

A continuous-flow procedure was hereby developed and introduced for the synthesis of etherified tryptophol derivatives. It evolved Fischer indolization and condensation in tandem by using Lewis acid as a catalyst. Solvent (alcohol) was considered to participate in the reaction sequence during the step of etherification which is not readily available through traditional approaches. The reaction time of heating and cooling was precisely controlled in flow that would benefit the scale-up (short residence time) and increasing yield (high selectivity).