Boron Trichloride‐Mediated Synthesis of Indoles via the Aminoboration of Alkynes

Abstract We describe an efficient catalyst‐ and metal‐free aminoboration of alkynes to 3‐borylated indoles using one of the least expensive boron sources, BCl 3 . The major dichloro(indolyl)borane products can be used for the in situ construction of useful 3‐Bpin indoles. This simple and mild method provides a novel and efficient approach for the synthesis of various 3‐borylated indoles with high regioselectivity and a wide substrate scope. magnified image