Compounds of structure (II)
in which R is hydrogen or C1-4 alkyl; n is 1 to 5; and R2 to R6 are the same or different and are each hydrogen, halogen, hydroxy, CI-4 alkyl, CN, N02, S02NH2, C02H, CONH2, CHO, CH20H, CF3, C1-4alkoxy, SO2C1-4 alkoxy, SO2C1-4fluoroalkyl or CO2C1-4 alkyl, and pharmaceutically acceptable salts thereof, processes for their preparation, pharmaceutical compositions containing them and their use in therapy as dopamine-β-hydroxylase inhibitors.