3.3](2, 5)-and [3.3](2, 6) pyridinophanes as well as [3] metacyclo [3](2, 5) furanophane (20) and [3] metacyclo-[3](2, 5) thiophenophane (23) have been synthesized by the conventional or modified TosMIC coupling reaction, followed by acid treatment and reduction. lH NMR data suggest that the stable conformation of the [3.3]-metacyclophane-2, ll-dione system (3, 6, 19, and 22) is anti, whereas that of the [3.3] metscyclophane system (4, 7, 20, and 23) is ...