Artificial receptor prototypes

Billing and Nilsson reported the cyclodimerization of a bifunctional molecnle 85 displaying both an azido- and an alkyne-group. A propynoyl-dipeptide was conpled to an azido-aminoglucopyranoside and cyclodimerized by CuAAC to afford 86 in decent yields (33-64%, Scheme 10.25). The prodncts were believed to be artificial receptor prototypes. A similar strategy was used to assemble macrocycle 87 containing two amino acid resi-... 

Calixarenes (from the Latin ca/ x) may be understood as artificial receptor analogues of the natural cyclodextrins (96,97). In its prototypical form they feature a macrocycHc metacyclophane framework bearing protonizable hydroxy groups made from condensation of -substituted phenols with formaldehyde (Fig. 15b). Dependent on the ring size, benzene derivatives are the substrates most commonly included into the calix cavity (98), but other interesting substrates such as C q have also been accommodated (Fig. 8c) (45). 

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