Chirality in Calixarene-related Systems

The interesting stereochemical possibilities for the large-ring spherand-type calixarenes 16, which include compounds with 3 and symmetry, are discussed in ref. 14e. The intriguing stereochemistry of the calixarene spirodienones 

239-241 is discussed in refs. 538 and 539. The concept of pseudo-C2-symmetry as applied to the dimethyl ether of p-rert-butyldihomooxacalix[4]arene (67) is discussed in refs. 14e and 566 for an A,B-diether in the u,d,u,u conformation. 

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