CoCl(PPh3)3 as Cyclotrimerization Catalyst for Functionalized Triynes under Mild Conditions.

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.