1,6-Dichlorohexa-2,4-diyne undergoes nickel-catalyzed double substitution with aryl and alkenyl Grignard reagents to provide substituted ene-yne-enes. The reaction is formally an extension of the well-described S_N2′-allylic and -propargylic substitution reactions but the mechanism is considerably more complex. The products might function as building blocks for conjugated polymers.