Abstract: A series of w-phenylalkyl esters of cyclophane 2 were synthesized. Cyclophane 2 has a cavity ca. 4.5 8, by 6 8, through which the phenylalkyl groups may pass. The activation energy for passage of the phenylalkyl groups through the cyclophane's cavity varies with structure in a manner which suggests dominant importance of alkyl group flexibility. These conclusions are supported by molecular mechanics calculations.
