Synthesis of 1H-pyrazino[1,2-a]pyrido[2,3-e]pyrazine and 2H-pyrano[2,3-b]pyrido[2,3-e]pyrazine derivatives

Article abstract of DOI:10.1002/jhet.5570330632

With a continuing interest on heteropolycyclic structures which may show biological activities, we synthesized new tricyclic derivatives in which the pyridopyrazine skeleton is fused with pyrazine 7 and 8, B, n = 1. However, the initial design of obtaining also the cyclohomologous structure B (n = 2) produced instead a pyranopyridopyrazine derivative 11. Thus during the attempt to prepare a pyridodiazepine intermediate, beside a very small amount of the desired product 10, the pyridopyrazine 9 was obtained. The latter compound reacted with chloroacetyl chloride/chloroketene to give 4-carbethoxy-10-(chloroacetyl)-5,10-dihydro-5-methyl-2H-pyrano[2,3-b]p yrido[2,3-e]pyrazin-2-one (11). In studying the behavior of this derivative, compounds 12-14 were obtained. Compounds 4b,c, 5a,b, 7, 8, 9 and 14 have been submitted to preliminary pharmacological screening as CNS depressant agents.