Regioselective Cyclotrimerization of Terminal Alkynes Using a Digermyne.

The catalytic activation of small neutral molecules followed by the formation of C-C bonds is a highly important method to increase the complexity and/or value of simple starting materials. Reported is an isolable digermyne, a compound with a Ge≡Ge bond, which acts as a precatalyst for the cyclotrimerization of terminal arylacetylenes to afford the corresponding 1,2,4-triarylbenzenes with absolute regioselectivity. The results demonstrate that bespoke main-group-element compounds can catalytically activate and transform small neutral organic molecules and induce the formation of C-C bonds.