Synthesis of Heterophanes Containing the Pyridine, Furan, and Thiophene Rings by the TosMIC Method

Article abstract of DOI:10.1021/jo00359a033

<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. 1H NMR data suggest that the stable conformation of the <3.3>metacyclophane-2,11-dione system (3,6,19, and 22) is anti, whereas that of the <3.3>metacyclophane system (4, 7, 20, and 23) is syn.In <3.3>(2,5)pyridinophanes (17a-d) the average deshielding effects for protons located pseudogeminal and pseudoortho to a nitrogen atom are found to be 0.28 and 0.15 ppm, respectively, as compared to those pseudopara to the nitrogen.