A convenient synthesis of functionalised 1-aryl-1,3-alkadiynes

A two-step, one-pot synthesis of functionalised 1-arylalka-1,3-diynes is described. A key feature in this approach is exploitation of the "acetylene zipper" reaction to obtain terminal 1,3-alkadiynes 3 from internal isomers 1. Without isolation, but after protonation, the 1,3-alkadiynes 3 are subjected to subsequent Pd/Cu-catalyzed Sonogashira cross-couplings with aryl iodides having both electron-withdrawing and electron-donating groups. The whole sequence takes place under mild reaction conditions to afford functionalised 1-arylalka-1,3-diynes 21-35 in high yields. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).