Synthesis of mutidentate imidazole-containing macrocycles

Abstract

All three possible monomeric macrocyclic produds and one dimeric product have now been isolated and spectrally characterized from the recently described3 macrocyclization reaction which leads to imidazole-containing coronands.Alkali metal ion promoted reactions provide a small selectivity for the largest of the three monomeric macrocycles, coronand 1, and leads to improved yields (57%). Regimelective internal vs external N-*lation of the imidazole derivatives of 1 is controlled by the counter cation employed. Small cations lead to external N-alkylation, while large cations lead to internal N-alkylation. This is evidence of selective cation binding within the cavity for the lithium and sodium imidazolates, but for potassium and larger ions, binding is at the external peripheral nitrogen atoms. Larger ions are likely excluded from the cavity because of the higher conformational energy costa involved.The X-ray structure of the symmetrically protected derivative of 1 has been obtained and confirms previous structural assignments. (1) (a) Di Vaira, M.; Mani, F.; Stoppioni, P. J. Chem. SOC., Chem. Commun. 1989,127. (b) Knapp, S.; Keenan, T. P.; Zhang, X.; Fikar, R.; Potenza, J. A.; Schugar, H. J. and references cited within. (c) van Veggel, F. C. J. M.; Bos, M.; Harkema, S.; van de Bovenkamp, H.; Verboom, W.; Reedijk, J.; Reinhoudt, D. N. J. Org. Chem. 1991,56,225 and references cited within. (d) Traylor, T. G.; Hill, K. W.; Tain, Z.-Q.; Reingold, A. L.; Peisach, J. McCracken, J. Am. Chem. SOC. 1988, 110, 5571-5573 and references cited within. (3) Street, J. P. Tetrahedron Lett. 1991, 32, 3333. J.

Efficient synthesis and characterization of novel bis‐heterocyclic derivatives and benzo‐fused macrocycles containing oxazolone or imidazolone subunits

“…[ 31–34 ] Many macrocyclic derivatives containing heterocycles as thiazole, pyrazole, and thienothiophene have been studied [ 35–39 ] but very little is known about using oxazole or imidazole as macrocyclic subunits. [ 40–43 ]…”