Synthesis of 2‐Aminotetralins via Pd‐Catalyzed Alkene Difunctionalization Reactions: Use of Ligand Structure to Suppress Facile Intramolecular 5‐ Exo‐ Heck Reactions

The palladium‐catalyzed coupling of 2‐(but‐3‐en‐1‐yl)phenyl triflates with amine nucleophiles affords separable mixtures of 2‐amino tetralins and 1‐aminomethyl indanes in moderate to good yields. The competing intramolecular Heck arylation of the starting materials can be effectively suppressed through the use of t BuPhCPhos as the ligand for palladium. Transformations of substrates bearing substituents on the alkyl chain proceed with diasteroselectivities from 5:1 to > 20:1. The scope, limitations, mechanism, and stereocontrol are discussed, along with the influence of ligand structure on reaction outcome.