Stereoselective synthesis of tetra- and tri-substituted alkenyl nitriles via aminative ring-opening of cyclopropenes with iron-aminyl radical

Abstract

Abstract The ring opening of cyclopropenes provides a compelling platform for the rapid synthesis of various polysubstituted acyclic alkenes. However, radical-mediated reactions of this type remain underexplored, and none of the existing methods have successfully produced tetrasubstituted olefins with high stereoselectivity. We present here an aminative ring-opening of cyclopropenes with iron-aminyl radical to afford tetrasubstituted alkenyl nitriles in a highly stereoselective manner. Computational studies indicate that both the substrate-directed radical addition and the following stereospecific ring-opening of cyclopropyl radical contribute to the extraordinary stereocontrol observed in the reaction. In addition, trisubstituted alkenyl nitriles could also be obtained using this method or via a base-promoted isomerization of the tetrasubstituted alkenyl nitriles, both with consistently high stereoselectivity.