Pericyclic reactions in the synthesis of new 5-aryl-5,6-dihydroquinolino[2,1-b]quinazolin-12-ones

Novel tetracyclic 5-aryl-5,6-dihydroquinolino[2,1-b]quinazolin-12-ones bearing benzo-15-crown-5 ether and dimethoxyphenyl moieties were prepared by one-pot cascade synthesis involving the thermally allowed pericyclic transformations of (E)-2-(2-methoxystyryl)quinazolinones. The pseudocyclic transition state of six-electron electrocyclization has been located and the activation barrier has been estimated by RHF/3-21G and 6-311G* calculation methods. The crystal structure of N-[4-(2,3-dimethoxy-12-oxo-5,6-dihydroquinolino[2,1-b]quinazolin-5-yl)-3-methoxyphenyl]acetamide was determined by X-ray diffraction analysis.