PROCESS FOR OBTAINING NEW PYRIMIDO/5,4-B//1,4/OXAZINE DERIVATIVES

The invention relates to novel pyrimido [5,4-b][1,4]oxazine derivatives of the formula (I), and the acid addition salts thereof, pharmaceutical compositions containing them and a process for their preparation. In the formula (I) (I) wherein R1 stands for a C1-4 alkyl group; R2 stands for hydrogen or halogen or an azido group or an -NR5R6 group, wherein R5 represents hydrogen or a benzyl group, or a C1-4 alkyl group unsubstituted or substituted by a hydroxyl group, R6 stands for hydrogen, an amino group, a C3-6 cycloalkyl group, a straight or branched-chain C1-4 alkyl group optionally substituted by a hydroxyl, mercapto, aminocarbonyl, furyl, 2-benzo[1,4]dioxanyl, di(C1-4 alkyl)amino group or by a phenyl or phenoxy group optionally mono- or polysubstituted by halogen or C1-4 alkoxy group (s) or by a 6-membered, saturated nitrogen-containing heterocycle optionally containing an additional nitrogen or oxygen atom and optionally substituted by a C1-4 alkyl or benzyl group; further NR5R6 may also represents a 6-membered, saturated, nitrogen-containing heterocycle optionally containing an additional nitrogen or oxygen atom and optionally substituted by a C2-4 alkoxycarbonyl or C1-4 hydroxyalkyl group; R3 and R4 are the same or different and stand for hydrogen or a C1-4 alkyl group; R9 stands for hydrogen or a C1-4 alkyl group unsubstituted or monosubstituted by an oxo, cyano, aminocarbonyl, C2-5 alkoxycarbonyl, pyridiyl, morpholinocarbonyl, or phenyl group or mono- or polysubstituted by OH group(s), with the proviso that R2 is different from chlorine, 4-morpholinyl and piperidyl group when R9 stands for hydrogen; or R2 is different from chlorine and 4-morpholinyl group when R9 stands for a methyl or benzyl group. The compounds of the formula (I) are capable to increase the myocardial contractile force (the performance of the failing heart) and the coronary blood flow, thus they can therapeutically be used for the treatment of the chronic heart failure and coronary disturbances.