The scope of thallium nitrate oxidative cyclization of chalcones; synthesis and evaluation of isoflavone and aurone analogs for their inhibitory activity against interleukin-5
The oxidative cyclization of 2′-hydroxy-6′-cyclohexylmethoxychalcones 5 using thallium (III) nitrate (TTN) in alcoholic solvents produced isoflavones 2 and (or) aurones 3 depending on the electronic nature of p-substituents on ring B. Chalcones with strong electron donating substituents (OH, OCH3) were exclusively converted to isoflavones 2. Chalcone with weak electron donating substituents (CH2CH3)