Synthesis of cyclophanetetrayne complexes from bis(propargyldicobalt) dication equivalents.

Nicholas reactions of the p-phenyl linked bis(propargyl acetate) complex (3a) with electron rich arenes give cyclophanetetrayne complexes (5). The use of bis(propargyl ether) complex (8) with (3a) allows formation of a mixed cyclophanetetrayne complex (9), and in addition gives retro-Nicholas/intramolecular Nicholas reaction product (2).