Dibenz[b,f][1,4]oxazepine derivatives, process for preparing the same, and pharmaceutical compositions comprising the same

A process for preparing a compound of the formula:

• ##STR19## (wherein R.sub.1 is a hydrogen atom or a lower alkyl group;
• R.sub.2 is a branched lower alkyl group;
• R.sub.3 is a hydrogen atom, a carboxyl group, a carbamoyl group, a lower alkoxycarbonyl group or a lower alkoxy group;
• R.sub.4 and R.sub.5 are each a lower alkyl group or may, when taken together with a nitrogen atom, form a heterocyclic ring selected from the group consisting of piperidino, piperazino, pyrrolidino or morpholino;
• A is a lower alkylene group) or a salt thereof by reacting a compound of the formula:
• ##STR20## (wherein R.sub.1, R.sub.2 and R.sub.3 have the same meanings as defined above;
• R is a lower alkyl group) with a compound of the formula:
• ##STR21## (wherein A, R.sub.4, R.sub.5 and X have the same meanings as defined above).

A pharmaceutical composition for preventing and treating circulatory diseases which comprises an amount effective for preventing or treating a circulatory disease of a compound of the formula:

• ##STR22## (wherein R.sub.1 is a hydrogen atom or a lower alkyl group;
• R.sub.2 is a branched lower alkyl group;
• R.sub.3 is a hydrogen atom, a carboxyl group, a carbamoyl group, a lower alkoxycarbonyl group or a lower alkoxy group with the proviso that both R.sub.1 and R.sub.3 are not hydrogen;
• R.sub.4 and R.sub.5 are each a lower alkyl group or may, when taken together with a nitrogen atom, form a piperidino, piperazino, pyrrolidino or morpholino ring;
• A is a lower alkylene group) or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.