Copper(I) Hydroxyapatite Catalyzed Sonogashira Reaction of Alkynes with Styrenyl Bromides. Reaction of cis-Styrenyl Bromides Forming Unsymmetric Diynes

An efficient Sonogashira coupling of terminal alkynes and styrenyl bromides has been achieved under the catalysis of hydroxyapatite-supported copper(I). The trans-styrenyl bromides produce the usual trans-enyne products, whereas the cis-styrenyl bromides lead to unsymmetric 1,3-diynes by the cross coupling of terminal alkyne and the alkyne generated from the cis-styrenyl bromide. A series of trans-enynes and unsymmetric 1,3-diynes have been synthesized by this protocol.