Scheme 3. Zawackis synthesis

It was converted to the phthalimide via a Mitsunobu reaction, reduced to the amine, and the amine was coupled with / -nitrophenylacetic acid to give the precursor to the macrocycle. Macrocylization was done via Troger s base formation using Johnson s method, which resulted in two isomers of the amide macrocycle. These were separated and reduced to give the cyclophane host. This was the first time two diastereomers were observed in these syntheses and the separation of these diastereomers was very difficult. 

5 % overall yield of both isomers from the dialcohol 

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Qingwu Jin repeated Zawacki s synthesis but the overall yields to the macrocycle were too low to continue further studies.30 Jin developed another route that closed the macrocycle via Troger s base formation (Scheme 4). The Troger s base diol was used as a starting material. 

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