Synthesis of Conjugated Triynes via Alkyne Metathesis

The synthesis of conjugated triynes by molybdenum-catalyzed alkyne metathesis is reported. Strategic to the success of this approach is the utilization of sterically-hindered diynes that allowed the site-selective alkyne metathesis to produce the desired conjugated triyne products. The steric hindrance of alkyne moiety was found to be crucial in preventing the formation of diyne byproducts. This novel synthetic strategy was amenable to self- and cross-metathesis providing straightforward access to the corresponding symmetrical and dissymmetrical triynes with high selectivity (up to 98%).