Pyranopyridines having antihypertensive activity

Abstract From the Canadian patent

A compound of formula (I) or a pharmaceutically acceptable salt thereof:, (I), wherein: one of R1 and R2 is hydrogen or C1-4 alkyl and the other is C1-4 alkyl or R1 and R2 together are C2-5 polymethylene;, either R3 is hydrogen, hydroxy C1-6 alkoxy or, C1-7 acyloxy and R4 is hydrogen or R3 and R4 together are a bond;, R5 is hydrogen; C1-6 alkyl optionally substituted by up to three halo atoms, by hydroxy, C1-6 alkoxy C1-6, alkoxycarbonyl, carboxy or amino optionally substituted by one or two independent C1-6 alkyl groups or disubstituted by C4-5 polymethylene; C2-6 alkenyl; amino optionally substituted by a C1-6 alkyl or C1-6 alkenyl group or by a C1-6 alkanoyl group optionally substituted …