Bis 3-acetylquinoxalin-2-on-l-yl alkanes

The interaction of quinoxalinepodands 156 (Kalinin et al. 2007 Kalinin and Mamedov 2014) with the acetyl moieties and ammonium acetate when heated in DMSO leads to the formation of the macrocyclic system. The process was accompanied by the formation of the pyrrole ring of 161 from the acetyl fragments of 156 and ammonia. The reaction was carried out in highly diluted mixtures in the presence of MgS04, capable of binding water and serving as a template for the synthesis of macrocycles which increases the yields of the cyclophanes 161 from 8-10 to 22-24 % (Table 5.1) (Kalinin and Mamedov 2014). 

The precursors of cyclophanes 161, i.e., podands 156 were prepared in four steps starting from 3-ethylquinoxalin-2-one 159 (Mamedov et al. 2(X)5a Kalinin and Mamedov 2009), the alkylation of which with dibromooxoalkanes leads to 160 with ethyl moieties. The transformation of ethyl acetyl fragments was accomplished in three stages bromination, the substitution of the bromine atom by the azide group, and conversion of azidoethyl fragments into acetyl function when heated in aqueous acetic acid. 

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