CH596205

Pharmacologically active 2-substituted-1,2,3,4,-6,7,12,12A-octahydropyrazino[2',1':6,1]pyrido[3 ,4-b]indoles corresponding to the formula WHEREIN X is a straight or branched chain alkylene group optionally interrupted by a CO or a CHOH group, R is hydrogen, lower alkyl, aryl, aryloxy, cyano, carboxy, carbalkoxy, dialkylamino, benzodioxanyl or 4-pyridyl, and X and R together may be hydrogen; Y and Z independently are H2 or an oxygen atom; and R' is hydrogen or a lower alkyl group. The compounds of the invention have tranquilizing and hypotensive activity. The inventive compounds are prepared by reacting an alkyl 1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indole-3-carboxylate starting material with ethyleneimine to give a 1-oxo-1,2,3,4,6,7,12,12a-octahydropyrazino[2',1':6,1]-pyrido[3,4-b]indole in which substituents are then introduced at position 2 by a variety of methods, before or after having hydrogenated the oxo group at position 1. Alternatively, an alkyl 2-chloro-acetyl-1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indole-3-carboxylate and a primary amine H2NXR are reacted to give a 1,4-dioxo-1,2,3,4,6,7,12,12a-octahydropyrazino[2',1':6,1]pyrido[3,4-b] indole, in which substituents are then introduced before or after having hydrogenated the two oxo groups at positions 1 and 4.