Crown pyrazole complexes

The synthesis of the 26-membered proton ionizable tetraester crown (289 R = H) has been performed either by Lewis acid catalyzed debenzylation of its 1-benzyl substituted precursor (289 R = benzyl) <91JCR(S)126> and by direct cyclization of pyrazole 3,5-dicarbonyl dichloride with the acyclic diol (291 R = H) <94T4765>. This symmetric receptor (289 R = H) strongly interacts with the amino group of homoveratrylamine affording a solid dinuclear complex (290) <93TL7299>. 

Becher <90JA3709> has studied by californium-252 plasma desorption mass spectrometry the alkali metal ion complexation of a crown ether containing two pyrazole subunits. Rebek <93RTC330> prepared one of his famous molecular clefts with two 3-/-butylpyrazol-l-yl substituents. 

The synthesis of cahx[4]arene dimelamines with different functionalities and their self-assembly with barbituric and cyanuric acid to hydrogen-bonded nanostructures have been published <05OBC3727> Unique ionophores of penta-crown ethers have been prepared by the reaction of l,3,5-triacryloylhexahydro-l,3,5-triazine (TAHTA) with diaza 18-crown-6 followed by Michael addition, and their binding capabilities towards alkali metal cations studied <05SL2257>. New silver complexes of polydentate ligands including a derivative of pyrazol-l-yl-l,3,5-triazine have been reported <05EJ14370>. 

---