First synthesis of a highly strained cyclodeca-1,5-diyne skeleton via intramolecular Sonogashira cross-coupling

Cyclization of alkenyl bromides 6 and 11 containing a terminal alkyne was achieved by using an intramolecular cross-coupling reaction catalyzed by Pd(0) and Cu(I). Under the optimal reaction conditions, cyclodeca-1,5-diyne derivatives 7 and 12 were obtained in 43 and 28% yields, respectively.