Transition-Metal-Free Regioselective Intermolecular Hydroamination of Conjugated 1,3-Dienes with Heterocyclic Amines

The unique property of hexafluoroisopropanol (HFIP) enables the regioselective hydroamination of 1,3-dienes with nitrogen heterocycles in a Markovnikov manner in the presence of catalytic Brønsted acid. This transition-metal-free intermolecular hydroamination protocol is achieved under mild reaction conditions. The aggregation by HFIP and Brønsted acid helps to activate the terminal double bond regioselectively. Following the protonation of diene, the C-N bond formation is accomplished upon the involvement of heterocyclic amines.