Use of acyl phosphonates as a coupling partner for rhodium-catalyzed [2+2+2] cycloaddition:: Unexpected dependence of the reactivity on structures of α,ω-diynes

A cationic rhodium(I)-H-8-BINAP complex catalyzes a [2+2+2] cycloaddition of 1,6- and 1,7-diynes with acyl phosphonates in high yields with high regioselectivity. Interestingly, the reactivity of alpha,omega-diynes toward acyl phosphonates is highly dependent on their own structures.