Fivefold Symmetric Aryl Amide Macrocycles

The reported stepwise construction of the macrocycles such as 16a nevertheless gives a very low overall yield of 5 % after months efforts [39]. Therefore, it would be of high interest to see whether these H-bonded organic pentagons can be made more efficiently by one-pot macrocyclization in shorter times (Fig. 9.7) [50]. 

Entry Coupling reagent Base Solvent Yield (%) 

NMP Af-methylpyrrolidone NMM JV-methylmOTpholine DMAP 4-diraethylaminopyridine Reaction conditions 17a (0.2 mmol), coupling reagents (0.4 mmol), base (0.6 mmol), solvent (2.0 ml), room temperature, 12 h Isolated yield by flash column chromatography No base is used No product can be detected 

Half-lives of H-D exchange data were measured at 2.0 or 0.2 mM in 5 % D2O/47.5 % DMSO-ds/47.5 % CDCI3 (v v) at room temperature 

3IG level show that the relative stability per repeating unit increases in the order of highly strained tetramer highly strained heptamer strained hexamer pentamer with or without explicit solvents (Fig. 9.8a-d) [50]. 

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