Pyrrolamidocalix[4]arenes: new receptors for anion recognition

✍ Scribed by Francesco Troisi; Carmine Gaeta; Teresa Pierro; Placido Neri

• Publisher: Elsevier Science
• Year: 2009
• Tongue: French
• Weight: 261 KB
• Volume: 50
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/j.tetlet.2009.06.110

✦ Synopsis

Pyrrolamidocalix [4]arenes 1-4, members of a new class of anion receptors bearing pyrrolic units at the upper rim of calix[4]arene macrocycle, have been readily synthesized in good yields. Derivatives 1 and 3, with unsubstituted pyrrole units, show a good selectivity for H 2 PO 4 À over F À and AcO À , while the presence of electron-withdrawing NO 2 substituents in 2 and 4 inverts the selectivity favoring more basic AcO À and F À . In addition, it is demonstrated that the flexibility of calix[4]arene skeleton, present in 1 but absent in 3, is very important in the fitting process that leads the amidopyrrole moieties to wrap the tetrahedral H 2 PO 4 À guest.