A cationic rhodium(I)/bisphosphine complex catalyzes carboxylative cyclizations of 1,6-diynes, leading to cyclic dienyl carboxylates, in high yields with high chemo-, regio-, and stereoselectivities under mild reaction conditions. E.g., in presence of [Rh(cod)2]BF4/BIPHEP, reaction of MeC竕。CCH2C(CO2Me)2CH2C竕。CH gave 90% cyclopentane deriv. I (R = CO2Me). [on SciFinder(R)]