Synthesis and Conformational Studies of Novel Calixarene‐Analogous Macrocyclic [3.1.1]Metacyclophanes

Hydroxy[3.1.1]metacyclophane 4c , which is regarded as an unsymmetric or uncomplete “homocalixarene” bearing a propane bridge, has been synthesized using Nafion‐H catalyzed cyclobenzylation. A novel “pendulum” type motion steered by intramolecular hydrogen bonding has been observed Demethylation of compound 4c with BBr 3 in methylene dichloride was carried out at room temperature for 3 h to afford the dihydroxy[3.1.1]metacyclophane 4b in 74% yield along with the triol 4a in 25% yield. Triol 4a was tri‐ O ‐alkylated with methyl iodide in the presence of NaH to yield partial‐cone conformer 4d in quantitative yield. Similarly, a significant amount of partial‐cone conformer 5 results in the case of O ‐alkylation of 4a with N , N ‐diethylchloroacetamide. 1 H‐NMR titration of partial‐cone amide 5 with NaSCN clearly demonstrates that a 1:1 complex is formed which is stable on the NMR time scale.