Ir and Rh complex-catalyzed intramolecular alkyne–alkyne couplings with carbon monoxide and isocyanides

Intramolecular [2+2+1] cycloaddition of diynes with carbon monoxide was catalyzed by Vaskaʹs complex (IrCl(CO)(PPh3)2) or IrCl(cod)(dppp), and cyclopentadienones were obtained in good to high yields. The first catalytic synthesis of iminocyclopentadienes was achieved by portionwise additions of isocyanides to a solution of diynes and Rh catalyst ([RhCl(cod)]2).