Synthesis of marine polyacetylenes callyberynes A-C by transition-metal-catalyzed cross-coupling reactions to sp centers

Efficient total syntheses of the sponge-derived hydrocarbon polyacetylenes callyberynes A-C have been achieved using metal-catalyzed cross-coupling reactions of highly unsaturated 1,3-diyne fragments as the key steps, namely: Cadiot-Chodkiewicz reaction under Alamis optimized conditions (sp-sp), sequential Sonogashira reaction of a cis,cis-divinyl dihalide (sp(2)-sp), and Kumada-Corriu reaction of an unactivated alkyl iodide (sp(3)-sp). This last approach constitutes the first application of a metalcatalyzed sp(3)-sp Kumada-Corriu cross-coupling reaction to the synthesis of a natural product.