A novel case of atom-efficient C-C bond formation of small molecules catalyzed by the facile organoaluminum compound

The environmentally friendly and inexpensive organoaluminum compound, diisobutylaluminum hydride (HAlⁱBu₂), acts as an efficient pre-catalyst for C-C bond formation by the addition of terminal alkynes to carbodiimides, which is a rare sample that the group 13 complexes to be used for catalyzing such reactions. Preliminary mechanistic studies revealed that the reaction is mainly carried out by initial hydroalumination of carbodiimide and followed by protonolysis with acetylene. A carbodiimide molecule was inserted into the Al-C bond of the generated alkynyl aluminum compound. The final product was obtained by the second protonolysis with acetylene.