Pharmacologically active catechol derivatives of formula I ##STR1## wherein R.sub.1 and R.sub.2 independently comprise hydrogen, alkyl, acyl, optionally substituted aroyl, lower alkylsulfonyl or alkylcabamoyl or taken together form a lower alkylidene or cycloalkylidene, X comprises an electronegative substituent such as halogen, nitro, cyano, lower alkylsulfonyl, sulfonamido, aldehyde, caboxyl or trifluoromethyl and R.sub.3 comprises hydrogen, halogen, hydroxy alkyl, amino, nitro, cyano, trifluo...