Thermodynamic cyclizations of a series of cinchona alkaloid derivatives are investigated. An extended quinine monomer 2:HO-Ce-OMe is prepared and cyclized to produce a mixture of cyclic oligomers. Combining the extended monomer 2:HO-Ce-OMe with the previously reported cinchonidine monomer 1b:HO- Cc-OMe under thermodynamic control produces a library of quinine-derived macrocycles. Two quinidine-derived methyl ester monomers 10:HO-Cd-OMe and 16:HO-Ca-OMe are also reported. Both are preorganized to form cyclic dimers; upon carrying out the thermodynamic cyclization on a mixture of both monomers only a small percentage (5%) of the hetero-dimer is obtained. Thermodynamic cyclization of the corresponding cinchonidine derived methyl ester 1b:HO-Cc- OMe with 10:HO-Cd-OMe results in the self-sorting of the two diastereoisomers.
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