[5+2] Cycloaddition of 2-(2-Aminoethyl)oxiranes with Alkynes via Epoxide Ring-Opening: A Facile Access to Azepines.

A new FeCl3 and BF3 ⋅OEt2 co-catalyzed tandem hetero-[5+2] cycloaddition of 2-(2-aminoethyl)oxiranes with a wide range of alkynes, including terminal alkynes and alkyl-substituted internal alkynes is presented. This is the first example of rapid and facile production of diverse 2,3-dihydro-1H-azepines through a sequence of epoxide ring-opening, annulation, and dehydroxylation with broad substrate scope and exquisite selectivity control.