Synthesis and conformational behaviour of new intra-annularly linked cyclophane possessing a 1,6-dioxahexa-2,4-diyne spacer

The new intra-annularly linked cyclophane 1 was synthesized in five steps from p-cresol by intramolecular Eglington coupling of precyclophane 5. From the 1H NMR data, it was evident that the cyclophane 1 exists predominantly as conformer 1a rather than 1b at room temperature.