Reaktionen mit cyclischen Oxalylverbindungen, 26. Mitt. Cyclokondensation von 4,5-substituierten Thiophen- bzw. N-Alkylpyrrol-2,3-dionen mito-Phenylendiamin

4-Benzoyl-5-phenylthiophene-2,3-dione (1) reacts witho-phenylendiamine to give the quinoxaline derivative2 which cyclizes either to the furo[2,3-b]quinoxaline4 or to the thieno[2,3-b]quinoxaline5 depending on the reaction conditions. On the other hand, the pyrrol-2,3-diones6 ando-phenylendiamine combine yielding the pyrrolidino[2,3-b][1,5]benzodiazepine derivatives7. The structures of all compounds were confirmed by IR and13C NMR spectroscopic measurements based on X-ray structure determinations of4/5 (mixed crystal) as well as7 b.4/5 crystallize triclinically in the space group P1 (Nr. 2) with two molecules per cell, while7 b crystallizes monoclinically in space group P21/a (Nr. 14) with four molecules7 b and four moleculesDMSO per cell. The reaction pathways leading to the compounds2,4,5, and7 are briefly discussed.