| abstract |
A compound of the formula :n wherein R¹ is hydrogen, halogen, hydroxy, lower alkoxy, lower alkyl or mono(or di or tri)halo(lower)alkyl, andn (in which R² and R³ are each lower alkyl), nand a pharmaceutically acceptable salt thereof, processes for their preparation and pharmaceutical compositions comprising them as an active ingredient in admixture with pharmaceutically acceptable carriers. The invention also relates to intermediates of the formula |