The present invention relates to compounds of formula I 1
wherein R.sup.1 is as defined in the specification
and to esters thereof which are hydrolyzable under physiological
conditions and to the pharmaceutically acceptable salts thereof. The
compounds of the invention are inhibitors of COMT and, thus, are useful
for the treatment of diseases for which COMT inhibition is beneficial.
The invention further relates to the treatment, control, or prevention of
diseases such as depression, schizophrenia, Parkinson's disease, and to
improve cognition.
