Tandem Annulations of Propargylic Alcohols to Indole Derivatives

Indole derivatives are important heterocycles in organic synthesis for serving as privileged building blocks for functional material and as key components in a lot of bioactive compounds. Propargylic alcohols, bearing alkynyl and hydroxyl functional groups, have emerged as promising feedstock materials for the construction of carbo- and heterocycles. Especially, in the last decade, the Lewis or Brønsted acid catalysed tandem annulations of propargylic alcohols to build structurally diverse indole derivatives have been well-investigated. In this review, we summarize two main synthetic strategies toward indole derivatives via the cascade reactions of propargylic alcohols: indole-ring formation involved tandem reactions and the direct function-alization of indole skeletons. We hope this review would help to develop new and more efficient protocols for the synthesis of indole-included N-heterocycles.