Catalytic Prenylation and Reverse Prenylation of Indoles with Isoprene: Regioselectivity Manipulation through Choice of Metal Hydride.

The basic industrial feedstock isoprene was employed as a building block to install prenyl and reverse-prenyl groups onto indoles. The regioselectivity can be manipulated by the choice of metal hydride. Reverse-prenylated indoles were attained with high selectivity when using Rh-H. By switching to a Pd-H catalyst, selectivity toward prenylated indoles was achieved. This regiodivergent method also features high atom economy without stoichiometric byproduct formation.