Compounds of formula (I) and pharmaceutically acceptable salts thereof: ##STR1## wherein: either one of R.sub.1 and R.sub.2 is hydrogen and the other is selected from the class of C.sub.1-6 alkylcarbonyl, C.sub.1-6 alkoxycarbonyl, C.sub.1-6 alkylcarbonyloxy, C.sub.1-6 alkylhydroxymethyl, nitro, cyano, chloro, trifluoromethyl, C.sub.1-6 alkylsulphinyl, C.sub.1-6 alkylsulphonyl, C.sub.1-6 alkoxysulphinyl, C.sub.1-6 alkoxysulphonyl, C.sub.1-6 alkylcarbonylamino, C.sub.1-6 alkoxycarbonylamino, C.sub.1-6 alkyl-thiocarbonyl, C.sub.1-6 alkoxy-thiocarbonyl, C.sub.1-6 alkyl-thiocarbonyloxy, 1-mercapto C.sub.2-7 alkyl, formyl or aminosulphinyl, aminosulphonyl or aminocarbonyl, the amino moiety being optionally substituted by one or two C.sub.1-6 alkyl groups, or C.sub.1-6 alkylsulphinylamino, C.sub.1-6 alkylsulphonylamino C.sub.1-6 alkoxysulphinylamino or C.sub.1-6 alkoxysulphonylamino or ethenyl terminally substituted by C.sub.1-6 alkylcarbonyl, nitro or cyano, or --C(C.sub.1-6 alkyl(NOH) or --C(C.sub.1-6 alkyl)NNH.sub.2 or, when Y is oxygen, one of R.sub.1 and R.sub.2 is nitro, cyano or C.sub.1-3 alkylcarbonyl and the other is methoxy or amino optionally substituted by C.sub.2-7 alkanoyl;one of R.sub.3 and R.sub.4 is hydrogen or C.sub.1-4 alkyl and the other is C.sub.1-4 alkyl or R.sub.2 and R.sub.3 together are C.sub.2-5 polymethylene;R.sub.5 is hydroxy, C.sub.1-6 alkoxy or C.sub.1-7 acyloxy;R.sub.6 is hydrogen or C.sub.1-6 alkyl;R.sub.7 is NR.sub.8 R.sub.9 wherein R.sub.8 and R.sub.9 are independently C.sub.1-6 alkyl, R.sub.8 is hydrogen and R.sub.9 is C.sub.1-6 alkyl or R.sub.8 and R.sub.9 together are C.sub.4-5 polymethylene; or R.sub.6 and R.sub.8 together are --(CH.sub.2).sub.n --wherein n is 2 or 3, and R.sub.9 is hydrogen or C.sub.1-6 alkyl; or R.sub.7 is CH.sub.2 R.sub.10 wherein R.sub.10 is hydrogen or C.sub.1-5 alkyl optionally substituted by halo, hydroxy or C.sub.1-6 alkoxy; or R.sub.6 and R.sub.10 are ---(CH.sub.2).sub.m -- wherein m is 2 or 3;X is oxygen or sulphur; andY is oxygen, CH.sub.2 or NH;the R.sub.6 --CH--CX--R.sub.7 group being trans to the R.sub.5 group; having blood pressure lowering activity, a process for their preparation and their use as pharmaceuticals.