Tetra-O-alkylated calixarenes in the 1,3-alternate conformation
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A general method has been developed for the preparation of tetra-O-alkylated calixarenes in the 1,3-altemate conformation (3a,c‒e) starting from p-tert-butylcalixarenes la,b using Cs2CO3 in DMF. The 1,3-altemate conformation was unequivocally proved by an X-ray structure determination of 3a. The scope of the reaction was investigated starting from a series of diametrically di-O-alkylated calix arenes 4a-e having different substituents R2 (t-Bu, CHO, NO2, Br, CN) at the para positions of the phenolic rings. The reactions of 4a-d (R2 = t-Bu, CHO, NO2, Br) yielded the corresponding tetra-O-alkylated calixarenes in the 1,3-altemate conformation 5a-d (51-73%). However, the dicyanocalixarene 4e gave the partial cone conformer 6 as the major reaction product. © 1992, American Chemical Society. All rights reserved.
author list (cited authors)
Verboom, W., Datta, S., Asfari, Z., Harkema, S., & Reinhoudt, D. N.