The invention provides a compound of formula (I):
##STR1##
wherein R.sup.1, R.sup.2, R.sup.3, and Y have any of the meanings defined
in the specification; as well a pharmaceutical composition comprising a
compound of formula I; intermediates and methods useful for preparing a
compound of formula I; and therapeutic methods for treating drug
addiction, Parkinson's disease or depression comprising administering a
compound of formula I, to a mammal in need of such treatment.
