A palladium-promoted route to 3-alkyl-4-(1-alkynyl)-hexa-1,5-dyn-3-enes and/or 1,3-diynes

Reaction of benzene solutions of arylacetylenes with 1 equiv. of chloroacetone and 2 equiv. of Et₃N, using a mixture of (PPh₃)₄ Pd and CuJ as catalyst, affords 1,4-diaryl-butadiynes in very good yields. Under similar reaction conditions aliphatic 1-alkynes yield mixtures of simmetrically disubstituted 1,4-dialkyl-1,3-butadiynes and of 3-alkyl-4-(1-alkynyl)-hexa-1,5-diyn-3-enes.