Chemistry of O- and C-adducts derived from 1,4-diazinium salts: the use of tetrahydropyrazines in the synthesis of condensed systems

1-Ethyl-2,3-dicyano-5-nitromethyl-6-methoxy-1,4,5,6-tetrahydropyrazine reacts with N-methylquinoxalinium iodide in the presence of triethylamine to form octahydro-2,4a,5,10-tetraazabenzo[b]fluorene-3,4-dicarbonitrile, while our attempts to obtain similar polycyclic products from stereoisomeric 5-(S)- and 5-(R)-(1′-nitroprop-1′-yl)-6-methoxy-1,4,5,6-tetrahydropyrazines derived from the reaction of 1-nitropropane with 2,3-dicyano-5,6-dimethoxy-1-ethyl-1,4,5,6-tetrahydropyrazine.