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
A phosphine-catalyzed ring-opening additionreaction of cyclopropenones with a variety of nucleophiles (NuH), including oxygen-, nitrogen-, sulfur-, and carbon-based ones, has been investigated, which produces potentially useful α,β-unsaturated carbonyl derivatives in high yields (up to 99%), high regioselectivity, and exclusive E-selectivity. The reaction proceeds in high efficiency under very mild