Fluorene Macrocycle

Significance

In attempting to synthesize linear polymers of fluorene derivatives with linkages in the 3- and 6-positions, the authors were surprised to isolate a significant quantity of a macrocyclic tetramer. The proportion of the tetramer formed is dependent on the monomer concentration, with lower concentrations providing more of the macrocycle 2a. As opposed to 2,7-dihalofluorenes, 3,6-dihalofluorenes are difficult to obtain, as evinced by the six-step synthesis of monomer 1. The authors began with a radical bromination of phenanthrenequinone followed by a rearrangement and three-step reduction, which after alkylation of the 9-positions, provided monomer 1.