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Pursuing our previous research on azaquinoxalinones (1,2‐dihydropyrido[2,3‐b]/[3,4‐b]pyrazinones) we prepared, through a reductive cyclization of N‐(3′‐nitropyridin‐2′‐yl)piperidine‐2‐carboxylic acids 3a‐c, a set of derivatives of a new tricyclic structure, 7,8,9,10‐tetrahydro‐5H‐dipyrido[1,2‐a:3′,2′‐e]pyrazin‐6(6aH)‐ones 4a‐c. Starting from these compounds we obtained substituted amides 5a‐c and, from 4a, the amidines 6a‐c. In the synthesis of 6, a dehydrogenation reaction occurred giving rise to 7. The compounds 9 and 10, characterized by a different ring‐fusion between the pyridine and pyrazine rings, were synthesized in a similar manner.

In pursuing the study on compounds obtained by condensation of N‐monoalkylated aromatic and hetero‐aromatic diamines with α‐ and β‐ketoesters, 7,8,9,10‐tetrahydrocyclopenta[e]pyrido[3,2‐b][1,4]diazepin‐6(5H)‐ones 4a, 4b and 5,7,8,10‐tetrahydrocyclopenta[e]pyrido[2,3,‐b][l,4]diazepin‐9H)‐ones 5a, 5b were prepared starting from 2,3‐diaminopyridine or 2,3‐diamino‐5‐chloropyridine and ethyl 2‐oxo‐cyclopentanecarboxylate. Compounds 4a,b and 5a,b suffer thermally induced ring contraction to the imidazolone derivatives 8a,b and 7a,b respectively and are unsuitable for preparing diazepinone derivatives. Thus the methylated diazepinones 15, 17 and 18, stable on heating, were prepared. Compound 17 was transformed into the clozapine analogue 22, through the diazepinthione 20 and its S‐methyl derivative 21.

Wie im Formelschema näher ausgeführt wird, werden nach an sich bekannten Methoden Chinolizidinyl‐alkyl‐amine (II), (IV), (VIII), (XIV), (XVII), (XX) und (XXVIII) sowie einige Derivate erhalten.