Coupling of Alkynes with Carbene Ligands to Tungsten‐coordinated Cyclopropenes and Their Stereoselective Isomerization to Vinylcarbene Complexes

The synthesis of cyclopropene complexes, not by ligand-displacement reactions but rather by coupling a carbene ligand with an alkyne at the metal, was accomplished for the first time for 1, R = H, Me. At temperatures above − 40°C, 1 undergoes stereoselective rearrangement to give the vinylcarbene complex 2.