Asymmetric calixarene derivatives as potential hosts in chiral recognition processes

Abstract

Abstract New chiral derivatives of 1 5 ,3 5 ,5 5 ,7 5 -tetra-tert-butyl-1,3,5,7(1,3)-tetrabenzenacyclooctaphane-1 2 ,3 2 ,5 2 ,7 2 -tetraol [( 1 ); tert-butyl-calix[4]-arene] were synthesized by coupling modified chiral quinuclidines derived from the natural-product-based alkaloids quincorine and quincoridine with the calix[4]arene 1 via either an ester bond or an amide bond. X-ray analyses of two products were performed. Applications of the products in asymmetric catalytic hydrogen transfer reactions are described. A protocol is presented to multi-substitute calix[4]arene at the methylene bridges, resulting in, e.g., 2,6-carboxyl-all-tert-butyl all-methoxy-calix[4]arene.