Abstract: The present invention relates to 1,3,6,7-Tetrahydro-7-oxoimidazo[4,5-c][1,2,6]-thiadiazine 2-oxide derivatives of the general formula (I): ##STR1## wherein R.sub.1, R.sub.2 and R.sub.4 are the same or different and represent an alkyl group, an aryl group or an aralkyl group, each of which may have one or more substituents; and R.sub.3 represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an aralkyl group, each of which group may have one or more substituents, and a process for their preparation. The imidazothiadiazine derivatives have hypotensive and vasodilating activities and can therefore be used as medicaments.

Abstract: Novel benzo[.alpha.]phenazine derivatives of the formula ##STR1## wherein R.sup.1 is hydrogen, halogen, methyl, hydroxyl or alkoxy, R.sup.2 is --COOR.sup.5 (wherein R.sup.5 is hydrogen, straight or branched chain alkyl, cycloalkyl having 3-6 carbon atoms, benzyl or phenyl) or ##STR2## wherein R.sup.6 and R.sup.7 are the same or different and are each hydrogen or lower alkyl, or R.sup.6 and R.sup.7 together with the nitrogen atom to which they are attached form pyrrolidine or piperidine), R.sup.3 and R.sup.4 are the same or different and are each hydrogen or lower alkyl, and n is an integer of 2 or 3, and the salts thereof are disclosed. These compounds have antitumor activity in mammals.