SYNTHESIS OF POTENTIAL RECEPTOR MOLECULES BY COMBINATION OF UPPER-RIM-FUNCTIONALIZED CALIX[4]ARENES AND PARTLY BRIDGED RESORCINARENES

Combination of upper-rim-1,3-difunctionalized calix[4]arenes 14, 16, and 18 with tribridged resorcinarenes 4 and 6 and A,C-di-bridged resorcinarenes 10 and 13 yields both 1/1 calix-resorcinarenes (22-24) and 2/1 calix-resorcinarenes (25,26). 1/1 Calix-resorcinarene 22 mainly exists as one conformer (a), but at low temperatures (- 60 degrees C) very small amounts (< 5%) of a second conformer (b) can be observed. Both conformers equilibrate via rotation about one of the C(arene)-N bonds, with an activation free energy (Delta G(not equal) of 13 kcal/mol. 2/1 Calix-resorcinarenes 25 and 26 are more flexible and exist as a mixture of conformers. In order to be able to rigidify the structure of 2/1 calix-resorcinarenes via rigid spacers between the calix[4]arene fragments, 1,3-diaminocalix[4]arene derivatives 31, 32, and 34 were synthesized carrying nitro, carboxylic ester, and cyano groups at the unsubstituted aromatic rings. With these calix[4]arene derivatives, three new, functionalized 2/1 calix-resorcinarenes 35-37 have been synthesized.