Synthesis, Structures and DFT Computational Studies of 3.1.1Metacyclophanes Containing Benzofuran Rings

摘要

3.1.1Metacyclophane (3.1.1MCP) 6 a containing two benzofuran rings was obtained by treatment of 3.3.3MCP-dione 5 with trimethylsilyl iodide. The precursor 5 was synthesized using (p-tolylsulfonyl)methyl isocyanide (TosMIC) as the cyclization reagent. The H-1-NMR spectrum of 6 a at room temperature reveals that it undergoes very fast conformational changes relative to the NMR time scale and that the phenolic hydrogen forms weak intramolecular hydrogen bonding with the oxygen of one of the benzofurans. O-Methylation of 6 a afforded the calixarene analogue, macrocyclic 3.1.1MCP 7 a whose H-1-NMR spectrum reveals that it adopts a cone-likeconformation in solution at room temperature and the alkoxy group is pointing above and away from the macrocyclic cavity.