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We have achieved the first catalytic enantioselective synthesis of planar-chiral metacyclophanes by means of cationic Rh(I)/(S)-xyl-H8-BINAP or (R)-H8-BINAP complex-catalyzed inter- and intramolecular alkyne cyclotrimerizations. This highly enantioselective catalysis represents a versatile new method for the preparation of planar-chiral metacyclophanes. 相似文献
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《Tetrahedron letters》2014,55(51):7089-7093
We performed X-ray structural analyses of the five- and six-layered [3.3]metacyclophanes (MCPs) 1 and 2 and the six-layered [3.3]MCP tetraone 3. In the solid state, the MCP moieties of 1, 2, and 3 adopt different conformations from those of the free MCPs in solution. In the five-layered [3.3]MCP 1, all the [3.3]MCP moieties adopt anti (chair/boat) conformations. In the six-layered [3.3]MCP 2, two three-layered [3.3]MCPs are connected by a [3.3]MCP in the anti conformation with completely parallel benzene rings. In the six-layered [3.3]MCP tetraone 3, the outer [3.3]MCP moieties and diones adopt general syn and anti geometries, respectively. However, the inner [3.3]MCP moiety adopts an anti geometry. Based on density functional theory (DFT) calculations, the most stable conformers of 1, 2, and 3 are syn (chair/chair) in the [3.3]MCP moieties and anti (twist boat/twist boat) in the dione moieties. 相似文献
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A novel and convenient protocol for the synthesis of hexahydroxy[2.1.2.1.2.1]- and octahydroxy[2.1.2.1.2.1.2.1]metacyclophanes from 4-substituted phenol in four steps has been developed. The synthetic route involved the preparation of the key intermediate 1,2-bis(5-substituted-2-hydroxyphenyl)ethanes in good yields via (i) formylation of 4-substituted phenol, (ii) reductive deoxygenation of 5-substituted 2-hydroxy aromatic aldehydes with low-valent titanium reagent and (iii) catalytic hydrogenation. The metacyclophanes were prepared by base-catalyzed macrocyclization of the above intermediates with formaldehyde in refluxing xylene in high yields. 相似文献
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Masahiko Shibahara Motonori Watanabe Chang Yuan Teruo Shinmyozu 《Tetrahedron letters》2011,52(39):5012-5015
In the solid state, the cyclophane (CP) moieties of the charge-transfer (CT) complexes of four- and five-layered [3.3]metacyclophanes (MCPs) 1 and 2 with tetracyanoethylene (TCNE) take different conformations from those in the solid state of the free MCPs. In the four-layered [3.3]MCP 1-TCNE complex, the CP moiety takes an s-shaped syn-anti-syn geometry, whereas the inner three benzene rings take the all-syn geometry and the two outer [3.3]MCP moieties have deformed anti-conformations in the five-layered [3.3]MCP 2-TCNE complex. In the crystal-packing diagrams of each complex, intermolecular CH/π-type interactions are observed between adjacent molecules. 相似文献
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