Strike while the iron is hot! A BF3‐mediated formal [2+2] cycloaddition between (1‐alkynyl)iron complexes and aromatic aldehyde imines occurs, which is followed by ring‐opening of the initially formed azacyclobutenes to yield (2‐alkenyl‐1‐imino)iron complexes (see scheme). The resulting iron complexes undergo deferric substitution reactions with water under oxidative conditions to afford the corresponding cinnamamides with high E selectivity.