The ubiquitary Co(I) complex CoCl(PPh3)3 was found to be a convenient catalyst for the [2 + 2 + 2] cycloaddition of functionalized triynes under mild reaction conditions and devoid of any additional additive, yielding the substituted arene compounds. Successful development of synthetic routes to various triynes and the subsequent cyclotrimerization key step gave systematic access to a variety of different bi- and triaryls with good to excellent yields for the cyclization.

The development of an in situ catalytic system based on cobalt­(II)-salts, chiral P,N-ligands, and a reductant for the intramolecular asymmetric cyclization of triynes is described. This system represents the first chiral in situ-generated Co­(I)-catalyst system for asymmetric [2+2+2] cycloadditions. The system consists only of commercially available components and leads to high yields and selectivities for the [2+2+2] cycloaddition of triynes in up to 16 examples.

The reaction of new, chiral, proline‐based naphthyl diynes with different nitriles through a key [2+2+2] cycloaddition reaction step catalyzed by CoI–olefin complexes under thermal and photochemical conditions gave diastereomeric atropisomers in good yield and nearly 1:1 ratios. Facile chromatographic separation of the naphthyl tetrahydroisoquinolines gave access to both pure and stable diastereomeric atropisomers. The deprotection and direct functionalization of the methyl‐ or methoxymethyl‐protected 2‐naphthyl position of the atropisomers were investigated. The configuration of the formed atropisomers was assigned from results of X‐ray studies and circular dichroism spectroscopy.

We report a detailed study concerning the efficient generation of highly active chiral rhodium complexes of the general structure [Rh(diphosphine)(solvent) ] as well as their exemplary successful utilization as catalysts for cyclotrimerizations. Such solvent complexes could likewise be prepared from novel ammonia complexes of the type [Rh(diphosphine)(NH ) ] . A valuable, feasible approach to generate novel chiral Rh complexes was found by in situ generation from Wilkinson's catalyst [RhCl(PPh ) ] with chiral P,N ligands. The generated catalysts led to moderate to good enantioselectivities and excellent yields in the cyclotrimerizations of triynes, showcasing their usefulness in the synthesis of axially chiral benzene derivatives.

The syntheses of two new indenyl-based cobalt(I) complexes were reported and their properties as catalysts in asymmetric cyclotrimerizations evaluated. While one complex was synthesized from a functionalized BINOL derivative by cross-coupling with 2-indenylboronate, the other complex was derived from a known chiral indenyl cobalt(I) complex by exchange of COD for two phosphite ligands, delivering the first chiral indenyl cobalt(I) complex, which can easily be activated thermally. The prepared complexes were tested in asymmetric cyclization reactions of triynes as well as diynes with nitriles to deliver chiral triaryls and heterobiaryls, respectively. While the BINOL-based precatalysts promoted the cyclizations in good yield without selectivity, the bisphosphite cobalt(I) complex induces chirality with up to 80% ee under photochemical as well as under thermal conditions.