A Macrocyclic Phenanthroline-Copper Complex with Less Steric Hindrance: Synthesis, Structure, and Application to the Synthesis of a [2]Rotaxane

We synthesized a macrocyclic 2,9-dialkyl-1,10-phenanthroline-Cu complex (9) from 1,10-phenanthroline. Compound 9 existed as a dinuclear complex in solid state. In solution, however, the compound existed as a mononuclear complex. Compound 9 mediated the Glaser reaction of an alkyne with a bulky blocking group and the formation of a [2]rotaxane was observed. The reactivity of the 2,9-diallcyl-1,10-phenanthroline-Cu complex (9) was lower than that of a diaryl analogue.