Synthesis of starburst oxadiazole compounds

Starburst oxadiazole compounds have been mentioned for the first time in a thermodynamic study of the structure-property-relationship in low molecular weight organic glasses [19, 20]. Upon rapid cooling these compounds form glasses with TgS between 77 and 169 °C. 

We have used three different approaches for the preparation of starburst oxadiazole compounds, which are schematically shown in Fig. 2.2. 

The methods A and B can be compared to the divergent synthesis of dendrimers. Method A starts from a central core and involves the reaction of the acid chloride groups and a subsequent cychsation with phosphorous oxychloride to the oxadiazole ring (Chap- 

In the third approach (method C) which is similar to the convergent synthesis a preformed oxadiazole precursor is prepared by stepwise synthesis and finally coupled to the core molecule. 

For the preparation of the novel starburst molecules, different core molecules have been used 1,3,5-benzene tricarboxylic acid chloride, l,3,5-tris(4-benzoyl)benzene, 1,3,5-triethynylbenzene, and 4,4, 4 trihydroxytriphenylamine. 

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